ATauer

Thank you! I have emailed Tony Hansen, who is such a wonderful human being about answering questions related to his blog posts, about his recommendation to have thixotropic glazes because of much it improves dipping and a long list of benefits, about whether he would recommend doing it for spraying and painting the way I’ve described, since I have a spray gun that can handle super super thick glazes and even latex paint, but still works for delicate little ceramics pieces, so depending on his answer, I may be making my glazes significantly thicker and using Epsom salts with all of them. If I do that, since I’d be using less water, I will do some tests to see if I need to adjust the amount of CMC water (and try to remember to come back here and report on results) in a thixotropic glaze or not. Depends I imagine on just how much less water I would use.

See my other post, people are abandoning lowfire bodies in droves because they are completely unusable, that is a lot different than just consistency issues we’ve always had to deal with. From what I hear, lowfire talc bodies are no longer extremely popular and they are also not fitting glazes so easy anymore. It is also not hypothetical- I’ve seen the data, I just can’t share it because it is in a class where everything is proprietary and I can’t share slides otherwise I would show you the data, that is robust and done using the scientific method appropriately. There have been plenty of lowfire bodies without any talc over the centuries that fit glazes fine, lots of terra cottas being used currently and for decades without any talc that also fit glazes fine, lots of wild clay bodies that are terra cottas that do well with glazes, it is very possible there are other reasons and other ingredients. Including the increasing improvement in commercial glazes, how they make them and what they put in them, that especially at low fire make them fit much better than they used to a wide amount of different claybodies, in fact some that fit pretty much every lowfire clay and often if you try even cone 6 and cone 10. Consistency has been an issue usually over the course of years for most materials, most mines take quite some time of producing the same material before that is used up and they go deeper and the chemistry changes a little which usually just requires some mild adjustment for the majority of things. There are some exceptions, like rutile, where they always say if you find some you like buy 50 or 100 lb to last you the rest of your career because it changes much more often in the mines and there are many different mines that are used and suppliers change them frequently for some reason without telling you. And over a number of years feldspar mines have been mined out or closed, so *sometimes* changes have to be made for feldspars, a lot kinda close together ran out but before that the feldspar changes had been usually with quite a few years in between- for me they don’t (not until the Canadian neph sye runs out) because I have a thing about not having a lot of feldspars taking up space, I alter almost every single glaze so I can use neph sye using glaze calc (amazing the number of glazes that has improved significantly) except the extremely rare times that it has has affected color or COE, but usually when I alter the glazes to use neph sye the calculated COE goes down to my surprise, if it needs Cornwall stone I have found I can’t glaze calc my way out of that but I have switched from using the stuff I can get at my supplier which I don’t know how reliable it is and do the home made recipe for consistency-plus it is all stuff I have on hand anyway. I try and limit a lot of my ingredients- I refuse to use wollastonite as it is a PIA and I much prefer whiting & just adding more silica. I try and alter things so I can use dolomite instead of talc, especially now. It is possible to not have much in the way of consistency problems if you know the materials that are problems- talc, Cornwall stone, feldspars, rutile, some metal oxides, etc, and find ways around them or buy big bags of certain problematic things and when you get to the point you need to resupply test test test. Over all consistency is not as much of an issue the same way talc has been an issue over the last few years, where month to month there are problems and changes. It doesn’t have to be like this in North America either, there are tons of talc mines in other countries, just no company is willing to ship over here. Yes it would cost more and that’s a bummer, but there are huge talc mines in lots of countries with pretty consistent chemistries and enough to last decades. I don’t understand why no companies will import them. Other countries do not have talc issues, they often have plenty of other sourcing and consistency issues but not talc. I’m trying to think of what I’m going to miss when I move to France, where talc is not an issue and I can get most of what I already use or they have consistent supplies of almost the same chemistries as what I have been using so my glazes shouldn’t change too much. I can even get mason stains, which I prefer, although I’d probably adjust to what stains are cheaper. From my conversations with French ceramic artists and my friends in nearby European countries who are fellow glaze nerds I should have a lot less problems getting things and have good consistency, and access to a ton of things I don’t have access to in the US, some things in particular that should improve my work considerably and a number of things that will allow me to do things I can’t do now. And while I don’t use it much, just in certain glazes, no talc issues!

Hansen doesn’t really have any evidence, that is what I pointed out, he has one data point. I have seen lots of data that I’m not sure if it is proprietary but it had a lot more actual evidence and appropriate scientific method where the control was the same thermal expansion as the clays without talc. I already posted what would need to be done with Tony Hansen’s anecdotal evidence to determine using a dilatometer if the talc actually increases the thermal expansion. His own explanation of what happens in lowfire bodies in fact argues against talc increasing thermal expansion. Talc bodies may have always been short and hard to work with what I’m saying is that people are complaining in large numbers throughout the country to the for Flux Sake Podcast and other people that the talc currently being used is much, much worse, to the point they can’t work with the bodies anymore at all. And there has been a clear, rapid change in school and park and small art centers that give lessons to converting to cone 6 instead of lowfire anymore (one of my former teachers did it just as I left her classes, still makes me mad she didn’t do it earlier) because the clays are so awful they can’t teach with them. I’m also seeing in a ton of Facebook forums hobbiests and even professionals asking for advice about cone 6 bodies and glazes as they have just converted because they couldn’t find a lowfire body they could work with anymore, many having been doing lowfire work for years and being very committed to traditional majolica or specific glaze colors that are harder to get at higher temps and doing it because they feel they have no choice. That is a lot different that just the status quo.

They are not dipping glazes, they are sprayed or painted, and it isn’t brushing as I pointed out (which typically just involves quickly brushing the glaze with a hake in three coats letting it dry between and that is it), it is painting, which involves diluting or the opposite, making thicker with gum arabic usually and adding CMC and often polypropylene to help with the painting,-which involves applying with a variety of different kinds of brushes in varying thicknesses and amounts, usually not counting coats but going for certain affects, shading, doing it just like you would paint a watercolor or oil painting on a canvas. So I’m asking how much CMC liquid the way you suggested making it up with the copper already in it as part of the water used for making the glaze. Right now, as I believe I said, I only add CMC to a separated portion of the main glaze for when I’m going to be painting. There are occasional times I also add it to a portion of a glaze that is going to be sprayed, if I feel for some reason it needssome extra help sticking to the bisque. Since they are NOT being dipped, ever, would you recommend altering your instructions, and could you give an approximate amount of CMC water to use when mixing the glazes.

I’ve only ever seen copper carb used for antimicrobial properties. I am not sure if there is any true difference in how it works, or whether there are different concerns for toxicity, I looked at an MSDS sheet for black copper oxide and compared it to copper carbonate’s, and there seems to be a bit more concern with copper oxide with inhalation and ingestion toxicity and its severity than with copper carb, ingestion we are going to rule out here as a concern so it is the MSDS sheet’s warning that inhalation could exacerbate other ongoing lung disease or from chronic exposure to cu oxide develop respiratory disease. It says the OSHA daily occupational limit is 1 mg/m^3 TWA, which with the small amounts we deal with and put in our glazes and especially in this CMC recipe I think it would be hard to get that high of a level of copper oxide in the air, even with dust and fumes, which is says to avoid of course. OSHA doesn’t even recommend wearing ventilators or dust masks unless the air levels are significantly higher than their limit, for up to their limit they just recommend good ventilation. So to try to come to a conclusion, I would suspect cu oxide would work just fine but can’t say 100% without testing because I just have seen it used for antimicrobial growth suppression. Copper carbonate is copper oxide with some added water, so honestly it is surprising to me they even have different MSDS sheets, but apparently they do have some slightly different issues with toxicity. I think there is no harm in trying and if your CMC enriched test glaze doesn’t go bad, then I would say go ahead and use it. It is too small of an amount to flux or color the glaze so there is little harm in it as long as you don’t eat it!

You said the right amount of soda and kaolin mixed starts to turn to a Nepheline around cone 0, while Nepheline Syenite when it starts to melt around cone 2 or 4 I think it is will end up on its own melting into a glossy glaze, it just crazes terribly because the amount of sodium in neph sye. I’m wondering if the Nepheline that forms around cone 0 with soda and kaolin would also form a glaze at around that temp or up to cone 06…which is how high I usually fire my raku kiln when I add soda ash to it. They always say at that temperature you can’t form any glazes, it isn’t hot enough, but they aren’t talking about the Nepheline, right? I’m probably groping in the dark here, I’m just wondering how I could use the fact that Nepheline is forming, which if it is close enough in chemistry to neph sye might form a glaze, even if it crazes, that wouldn’t be a problem with raku work. I’m just trying to figure out if I can use this new knowledge to produce something at cone 06….

Yeah, the markings appear on both the terra sig and the clay body, it seems to just affect any clay it seems, doesn’t matter if it is in slip form or from a body. It seems to stand out more over the terra sig though, it is not as noticeable on the bare clay, probably because of the color and sheen of the terra sig versus the matte clay- plus I have only used it on porcelains & porcelaneous stoneware so far personally so they are very white clays and the white from the soda ash isn’t very noticeable then. I am planning on using it on some speckled light brown stoneware and black stoneware I have soon though and I think it will stand out more on them. I feel like calling it scum makes it sound a lot worse looking than it is, I could also say it looks a lot like when your car gets scratched and has white marks, or a metal tin gets scratched, or even scratched antique wood- maybe that is a better analogy, because sometimes scratched antique wood looks very nice. If I’m using the soda ash wash instead of borax or lithium (both tend to have much more of a sheen, but can also leave some marks, the lithium especially I think if too much is put on kind of bubbles up, but they are much more consistent in leaving a sheen- I mean some people still use saturated borax washes or borax with minimal other ingredients to form a low fired glaze!) it is because I want the white marks which have a distinct look that makes the object look antique and old, my favorite is to use it over Grolleg terra sig colored with either the Bermuda or Celadon mason stains, which look a lot like an opaque burnished celadon/light turquoise, and put the soda ash wash over that and it looks absolutely gorgeous with those colors and the markings. I usually try to avoid getting it on the bare clay but again with my clays it doesn’t show up much anyway. I’m thinking of trying it on my black stoneware on the raw clay, no slip or terra sig or glaze, I think it will look very interesting, since from what I’ve seen of it it works about the same on every clay, so I’m pretty sure it should develop the same on black stoneware. You can also adjust, with some degree of control although not totally, there are plenty of times I’ve put it on and it did want it is really supposed to do, leave a sheen with no white marking, based on how much soda ash you have saturated in your water how much of the scum stuff shows up, it can vary from very little to almost completely covering up all the terra sig. I try and usually aim for the middle ground, so I don’t use a completely saturated solution. Unfortunately I don’t have access to my notes right now about how much I use, it is something like a teaspoon or tablespoon of soda ash per cup of water, probably a teaspoon as a tablespoon for a cup of water sounds like a lot to me right now! I’ll be very interested to hear your results. I’m hoping to begin doing some reduction firing soonish and eventually some soda firing, and I haven’t had any interest in flashing slips because I’m not a fan of the colors orange and brown/tan, which are most often the colors you get with flashing slips, although I do hear you can get reddish sometimes. But if washes alter how they look I might develop an interest in trying them. If only the flashing was a real nice red a lot more I’d be banging down the door to start using them. As it is, my plans to move to Europe in little over a year will result in me starting to definitely do soda firing, and maybe salt firing. I’m mostly interested in the wonderful clear glaze they can provide, and some of the affects of the process on glazes, colored slips, and underglazes you decorate with, without flashing or carbonization. I’m sure all the atmospheric people are shaking their heads at me, thinking about all I’m missing out on! I use soda in my raku kiln, the temperatures aren’t high enough to form a glaze although when I put an equal amount of borax in the newspaper twists I fill and dunk in water and throw in the kiln, it comes so close to making a glaze. But it induced immediate deep in kiln reduction, and has really interesting different effects on the glazes, bare clay, and slips on the ware that I love- and for one thing turns my copper luster pots blood red just perfectly, the only way I get really good looking “copper red” pots right now. I wonder if it would work on flashing slips at that low temp or not…no one has ever mentioned them when discussing lowfire or raku soda to me but I probably need to buy that new book that came out on lowfire soda firing.

I would need to go back and find that lecture and watch it again, I paid attention a lot to the rant about talc as a lowfire flux because it was a real hopped up rant which is always entertaining but since I have no interest in lowfire bodies I was not as interested in the rest of that part, mostly I remember seeing some charts and I think him saying that the other so-called benefits of using it in lowfire bodies didn’t really have the evidence to back up those claims and I thought I saw some proprietary data on it. But I will have to go back and rewatch to make sure about that part. I think the point was like we see in the Digitalfire blog photo I linked to, talc is inert at those temperatures, if it isn’t melting then it can’t be affecting the thermal expansion, because it’s oxides are not active. They are just a powder that doesn’t melt, and don’t interact with the rest of the materials. That’s what I’m remembering as the reasoning. That it of course does very much act to *lower* thermal expansion at cone 6 and cone 10 because of the effects of Mg. That it wouldn’t have any effect either way in a lowfire glaze, either, same reasoning as before, its not melting and interacting with the rest of the glaze materials. As a thought experiment, based off of the photo proving that talc does not melt *at all* at lowfire temps, something I’ve seen before too, pictures of it not melting, then the material doesn’t interact with the other materials during the firing, which it would need to do to increase expansion. I would think that it would just keep expansion the same as if it wasn’t in the clay, as it isn’t lowering or raising it. Tony mentions that all the minerals are just sintered and mostly just remain the same. Which to me would indicate that the Mg wouldn’t do anything to the thermal expansion. I know he shows a graph too, so I’ve got fighting graphs to contend with, but using dilatometers is notoriously tricky and not easy to get accurate results. I would need like a bunch of trials, not just one time that he did this on one clay, but 20 or 30 repetitions and also several versions using different clays with talc in them, (which Matt showed us talc in a variety of clays all not fluxing at all at that temp), that’s what I would do in a clinical trial basically, in order to get the best information, including a control low-fire clay with the exact same ingredients as the first one but without the talc to really evaluate it. I never trust one time dilatometer results.

This is a great way to do it, I have only heard of directly adding the cu carb to the glaze! Which is still good to know how to do in case you forgot to mix up your glaze this way. For me I’m a little unsure how much I should use when mixing glazes, I spray versus paint (not brushing, but literally doing as they say “in a painterly fashion”) about 50:50. And while there are some glazes I will know I will definitely not be painting with (floating blues for example) a lot of glazes can go either way. What would you suggest Min? They are such different things, and when I paint a lot of time I’m diluting the glazes a lot to make them more like watercolors, or doing the opposite, thickening them with gum arabic to mimic oils or acrylics. And even if I don’t have a ton of glaze issues to worry about, I like having CMC in my glazes, it comforts me knowing the CMC is really attaching that glaze to the clay, even if it might dry a little slower, so what, I’m a sculptor, I’m not on a deadline to glaze 50 mugs in a day. Another thing I’d love some advice on is I’m going to be working soon on trying to optimize single firing my very large scale sculptures that are cut into sections to fit in the kilns, doing so would save me a bunch of firings. It is hard enough to figure out how to optimize it without spending the large amount of time to make a bunch of 6 ft tall sculptures to practice the firing and glazes on, thinking about how I might use this with single firing and likely with pretty long schedules because of the size of the pieces…although I don’t know that for sure yet, I make them out of paperclay porcelain, so their walls are actually quite thin even if they are huge. So they shouldn’t need as long as a regular large scale sculptor who use thick groggy clay with 2.5 inch-3 inch walls would…Would you recommend using this at all with single firing (which probably could benefit from it as the clay is not going to be as thirsty and porous as bisque), does it matter at all if it’s put on before bisque or if the glazes are fired for longer than is typical? Probably tough questions…

I just wanted to add, I found on the Bartlett website a document on what you need and how to put together the complete controller from what you get when you buy it. Down at the bottom for V6-cf besides the manual and firing profiles they have the connections diagram, which is one of the best electrical diagrams I have seen over the last few months, and the technical manual, which includes some things that would help with putting it all together. https://www.bartinst.com/manuals/kiln In November I think I called them trying to find out about if it was a faceplate or a controller, which lead to a lot of my confusion about things, but the customer service was really nice and I think I might have talked to a tech there, an older gentlemen who has been with the company a long time, so I think if I need help I can probably get some help with putting it together from them. Cross fingers they are like Skutt’s techs.

I know just enough about PIDs to know about the loops, but your information was very helpful. I guess the misunderstanding was I was thinking with the Bartlett I would still have to do the programming and didn’t realize it came with so much. Having everything you mentioned-I don’t have three zones currently in my kiln but it is a big enough Skutt that I absolutely could go that way if I start noticing big differences between sections. The other things-especially the fail safe programming, which I worry about, although I do use the kiln sitter with a cone several cones higher than what I am firing to to make sure that if my electronic controller doesn’t turn off the kiln the kilnsitter will if the kiln starts heating up and might cause problems on another kiln, the multiple programs, alarms….since I absolutely can’t find any commercial kiln electronic controllers for anything under $800 + shipping $$$, paying ~$300 plus the ~$100 in parts I already have (not counting some parts I won’t need that I will be able to sell for a decent return) is a price I’m willing to pay to get rid of this headache and not have to stress about it any longer, and the side benefit of not having to brush up on my coding! Thank you so much for taking the time to make it really clear what I would be buying and that I should easily be able to put the rest of what it needs together with what I have, and probably have a number of things left over to sell as well. I feel super confident in deciding to go for it, and I feel like 50 lb has been taken off my shoulders-thank you! Now to wait to Monday to make the call to make sure I know exactly what I’m getting at the place I plan to buy it and hopefully purchase it!!!! One of my big needs taken care of, finally! Now let’s see if you can pull a giant electric kiln out of your hat I feel like the downside is we still haven’t identified the perfect RaspberryPi controller for the readers. I know I desperately wanted for many months of googling to just come upon something that mentioned it!

My experience with soda ash washes is not directly related to how you use them, but I thought the information might be valuable because it involves using them with terra sigillatas which are a kind of slip, and though typically thinner and made out of smaller particles, I use Grolleg terra sig quite a bit which is at least a porcelain which most flashing slips are also. I use terra sig in a variety of ways, some fairly traditional but most of the time not traditional. I often fire it at cone 6 or 8 in oxidation, and lowfire it in raku usually at cone 06 but sometimes down to 1700F, which is often in-kiln reduced as well as the post fire reduction, so definitely different than high fire reduction but still legitimate reduction and not just post-firing. I use a variety of washes and often glazes over it, or leave it plain (or colored with mason stain and unglazed). In both oxidation and the lowfire gas reduction, the soda ash wash tends to leave, I’m not sure how best to describe it, whitish almost scum markings, which can actually look very attractive and are usually the reason I use it, because it makes that part of the ware look antique and old in a good way. To ensure I get that I apply a decent amount over the top of the terra sig in bone dry or bisque. If I want a sheen I definitely don’t use soda ash- which when applied under the terra sig has less of an affect on the surface but definitely doesn’t leave a sheen. I know it theoretically can with terra sig but I’ve never seen it actually happen with anyone I know, or myself, and I would think it would have a good chance of leaving white scum/scruff marks and dotting on slip as well. If I want a sheen I use borax or lithium carb washes instead. Often under the sig, that tends to lessen the amount of sheen possible by a little (not so much it makes a huge difference) but it dramatically reduces the odds that either will leave any marking or rough up the texture like putting the washes over the sig might. Not a lot to help you with, but the fact that soda ash washes leave, just pretty much every time, that whitish scum and spots and streaks on a different kind of slip just means I would urge some caution- and I know for a fact it does it in gas reduction as well. Hopefully it would do that less at cone 10 as it ideally should flux better, but I know people who have been disappointed with seeing those results after a cone 10 gas reduction. I would suggest while you are experimenting maybe trying out borax and lithium carb washes too, they can produce just gorgeous sheens on sig at cone 6 and would fully flux at cone 10, making them likely to have a stronger sheen/be quite shiny even in gas reduction as well, although I have no idea about flashing. Hope this helped a little, and wasn’t too different to be of use.

Just for those of you who haven’t had the benefit of seeing Matt Katz lecture in his CMW Intro to Clay class were he rips apart all notions that talc acts as a flux in clay at lowfire temperatures, particularly the 06-04 range using a huge amount of data he has amassed through a bunch of experiments. There isn’t that much information on this out there that has been published though, and there are still a lot of clay suppliers who are making lowfire clay with up to 50% of it made of talc. I know there are some ideas it helps with glaze fit and crazing but he also showed us there was no data to support that in lowfire claybodies. Anyway, I came across this little experiment Tony Hansen did on Digitalfire which also includes some interesting visual data about some other materials as well! Matt’s suggestion to us was of course to fire to cone 10, because that is what he wants everyone to do always anyway, lol, but basically urged us if we were to be buying lowfire clays (including reds/terra cottas, talc is put in them a lot as well) to ask the suppliers for a data sheet on the materials in the clay to make sure there is no talc in it, and if the supplier won’t give that to you its time to change suppliers. At the very least you are entitled to the MSDS sheet on the clay and talc is a material they would have to list-just check the date and make sure it isn’t 20 years old which I’ve often found & usually they’d had recipe changes in that time. And no, I am not anti-talc, I quite love talc at higher temperatures in glazes! I’m quite worried about our future with talc, yes I know there is Cim-talc but I’ve been told it performs terribly in glazes by someone who should know, and it seems like any time a mine becomes available it is lost to us 6 months later. Our materials, as this linked blog post shows, are just so important to us, and without consistency…. https://digitalfire.com/picture/1115

CMC definitely burns off! It is methylcellulose, so glue basically made from the fibers in trees. The way I use it I usually don’t put it in a big 5 gallon bucket of glaze because it can rot, I remove a portion of glaze that I am planning on using soon and add the CMC just to that, that way it won’t rot. But it doesn’t help your 5 gallon bucket of glaze, unless when you add CMC to it you add a pinch of copper carbonate. I learned that on Glazy from a real super star of a glaze maker/inventor, and it makes tons of sense to me because I use 0.2% per dry weight of cu carb mixed with my paperclay to keep it from growing mold and the cellulose in it breaking down, and it works so well the clay will last for at least two years. I don’t think anyone has left the clay longer than that to see how long it could really go. It is used interestingly enough in antimicrobial cleaners in baby wards in hospitals for its antimicrobial/anti mold properties, while having an extremely low risk of toxicity of any kind. Been used like that for decades if not longer, so it legit will keep your CMC from rotting the glaze without having really any toxicity issues you need to worry about unless you drink your glaze, and even then I happen to know the dose would be too low to give you any symptoms! I know a pinch is rather hard to measure! You want enough to prevent rotting in the glaze without adding color or fluxing the glaze. You kind of have to play around a little to know how much that is, but around a 1/2 teaspoon to 5 gallons of glaze often works. There are other variables, like the weather, humidity, heat levels etc where you keep your glazes in how much it will want to grow bad stuff, so you may have to play around with the amount. And CMC in powder form is quite cheap, cheaper than anything else I’ve seen for the problems it treats. Just randomly, as I know you’ve said some of your glazes get cracks in them on the bisque and some of those types of issues, another thing you can do to help with that is use Karo syrup in the glaze (only the amount you are going to apply) and it is so sticky that it seals the glaze to the bisque and makes issues like that disappear. It often makes brushing on glazes much easier as well if you need to do that and your glaze is formulated for dipping. Which brings me to a thought I’ve had about your glazes, and adding binders and stuff- making sure you know the difference between a dipping glaze and a base coat dipping glaze, and make sure you are aware of which one you are making, and how that effects application and firing and flaws…this is especially important if you are dipping more than once, or layering. Two great links on the differences between the two and what you need to do and what to look out for…it may be that some of the problems you are having is you are using one when you should be using the other… https://digitalfire.com/glossary/base-coat+dipping+glaze https://digitalfire.com/glossary/dipping+glaze

You also might want to look at your bisque and glaze firing schedules again. A lot of the firing flaws could potentially be fixed by a drop and hold and slow cool schedule, I don’t think you mentioned what you do, I’m making an assumption you fire to cone 5 or 6 so if you lowfire or are cone 10 the exact cones I mention are not as important as the points I make about them. Make sure you are bisqueing at the right temp for these glazes and consistently using the same temp for the bisque, no over firing and always use the exact same cone consistently without fail (witness cones!). The only exceptions are you can bisque lower if you are doing raku or pitfiring/barrelfiring/saggarfiring. And you might want to look at the glaze temperature you are firing to, according to your cones, maybe that needs to be altered if your kiln’s programmed cone is actually different than the right temp for that cone, it may need adjusting. As Matt Katz is always reminding everyone, cone 5 is super far actually from cone 6 when you look at the degrees, compared to the distance between other cones. Glazes can perform very differently between the two, even though people say cone 5/6 like they are the same thing, and even just with over firing to cone 7 which a lot of people do a lot without knowing it. Getting all the way to cone 6 if you don’t use witness cones with every firing could be a problem, or if you are firing to cone 5 a lot of the glazes may be underfiring. And you’d be surprised sometimes how small of a range some glazes have, where cone 7 is hugely over firing…while others can fire from cone 06-10 (that’s really just the Stroke & Coats and the reverse engineered recipe for them on Glazy, but there are a surprising number of glazes that work from cone 4-10 with minimal visible changes.) Good luck, I hope you find something that helps.

Texas talc certainly caused a ton of problems, but largely just with claybodies, not usually with most glazes, though I have known some people who were able to isolate that the Texas talc was the problem with a specific glaze. But usually not all of their glazes. And it wasn’t common. That talc significantly changes the claybody color, instead of being bright white it made all the lowfire white clays dirty buffs that were very ugly, and it caused them to be very short and crack a lot, and had a bunch of other flaws I won’t list all of them, but it was a nightmare. But talc doesn’t contribute color to glazes and all the types of flaws it caused in claybodies are things that don’t really apply to glazes usually. I hope you are able to identify what is going on, I would try if you are able to mix up 100 gram batches of your glazes that you are having problems with each with an ingredient changed, and see if the glaze behaves differently. That would help you determine if it is a specific material that is a problem-you could start with just one of the problem glazes and try that and you might already get your answer. The other thing to do is compare all the recipes and see if there is one or more ingredients that is common to all of them and do a test batch without it or with a different brand you might buy a very small amount of from another supplier. It is strange that all of them would be doing all these things, and the variety of flaws. You might want to look at how you mix yours up, whether you need to ball mill (if you don’t have one you can get a cheap rock tumbler and buy the porcelain balls for it for $10, and it works great, that’s what I use) or sieve more. What you use to mix them, you might want to try something else. Make sure you have enough clay in each, definitely measure SG when you have gotten it to a viscosity that is good where it is behaving and monitor it and add water or deflocculant as needed to maintain that SG.

I The fast fire kiln design I would use uses very little wood, you can literally fire it with scrap wood, and it produces about less than 1% emissions of any kind. The ashes are reusable. Gas is never clean, they may be able to find ways to make it so not very many emissions are produced, but the process of obtaining and processing any of the gases used is extremely harmful environmentally, one of the dirtiest things humans do. I feel absolutely horrible using propane for raku but I have no other choice right now and I try hard to be as efficient and use as little as I can, so I at least don’t make it worse by using a lot. I took extreme care with building/designing my raku kiln to be as efficient and use as few BTUs per hour as possible, and then even added rigidizer and ITC-100 to make it even more efficient. Gas may be easier but it is not easier on my conscience. Fast fire kilns on the other hand can be decently sized, similar to the average gas kiln, about 20-30 cubic ft or so, but use a very small amount of wood which is a renewable resource in France where I would have this and if I’m lucky to get enough land I would grow bamboo to help fire it, which is extremely renewable and removes carbon while growing. have experience using the command line, quite a bit of experience, but it has been several years and my computer is dying and I can’t afford to buy a new one right now, I will be getting by on my iPad Pro which is what I use all the time now. But you can’t program RaspberryPi from an iPad to my knowledge, you need the command line etc. If I was recommended a good program I might be able to use my mom’s laptop to do the coding. The coding is not the problem, I know it will come back to me if I watch a few youtube videos. It is having enough information about how to wire together everything and like I said above, even be told how the breadboard connects, there are no directions with any of the components and the RaspberryPi program I was originally going to use from github does not have enough information about building it, the electrical diagram is missing a bunch of key components and is very confusing, which is why I eventually gave up and started looking for a simpler PID I don’t need half the components for and have as simple interface sadly without the wifi and checking the kiln on my phone, but I can’t do any of that stuff with my other two kilns so a simpler PID that just ideally would save some segmented programs would be fine. I’m sure I’ll eventually find one like that, if I can find the right website that sells ones like that. Someone has to make them, these other ones are so damn close to just right.

Sorry, I wasn’t clear enough, when I said the tuning didn’t worry me it was because all the PIDs I was looking at had auto-tune and in the descriptions described how often it tunes itself and that the process is automatic. Otherwise I would be more concerned, but literally every single one had auto-tune, even the $16 ones! They mostly all seemed pretty great, with a lot of good features and most importantly with thermocouple input (K type for me) they measured -50C to 1300C as some other PIDs I was originally looking at, like the Inkbird ones, did not handle the appropriate temperatures. The problems is I’m still searching for one that will save segmented programs, which I hope is out there even if it is a bit more expensive. I’m just starting to figure out where to look for PIDs, I’m only on the one website AliExchange right now. eBay was a nightmare. I already have all the parts for a complete PID, including the Raspberry Pi if I were to use that instead of buying one of the temp control PIDs. I have the metal box, the SSR, breadboards, heatsink, transistors, the thermocouple and its computer piece it plugs into etc. I would be all set if I could just find a better kiln controller program, or to use some of this stuff with a PID if I don’t go the RaspberryPi route.

I’m having an impossible time finding any PIDs so far that save multiple programs. There are some very reasonably priced that otherwise have great qualities, and they do segments- 32 segments! 50! But they don’t save them and they don’t have more than one it appears. The tuning doesn’t worry me, what I’ve read about it it sounds pretty easy. I just want to find one that will save multiple programs. Maybe there aren’t any, and I will have to settle for putting in my firing schedules manually every single time. I have looked at the Bartlett V6cf and the price is right at some places, but it is always very unclear if they are selling the actual controller, or just the faceplate. Because most places I have enquired including at Bartlett itself they say they only sell the interface, and I would have to pay someone to build a box and put the SSR and and some kind of PID I assume and all that stuff in it, and when they quoted me how much that costs, on top of the cost for the interface, it is basically as much as the Orton standalones which are already put together and ready to plug in, although nearing 1K these days, in the fall they were a lot cheaper. And it drives me nuts because I know these things they are selling for so much money are simple PIDs, they even say they are PID based, and I know I’m smart enough I could put one together with a little help, just some background in electrical work and brushing up on my coding. I hate the idea of paying over 1K for something I know I could make for under $200. But the frustration, and the amount of time it takes up, and how much it delays me being able to use that particular kiln are things I have to consider. If it was something I knew I couldn’t figure out it wouldn’t bother me so much, I’d just find the money somewhere, but the fact that I know I can make these….

I know this thread is a couple years old by now, surprised it isn’t archived. I was super interested, thank you for providing so much detail as you went through the process. I got a “free” Skutt KS-1227-3, basically the second biggest kiln they make, except they seem to have not very long ago discontinued the KS line, but of course what I was told, by the woman who gave it to me who knew nothing about ceramics having never touched clay (super great Mother’s Day present from the Dad, ha! She scared the hell out of me so I can only imagine how this clearly clueless husband suffered after buying a broken down kiln at a school auction and gave it to her for her gift, men, sometimes!) was that it only needed new elements and a new cord to switch it make to its original 240 volts single phase so I could use it at home instead of the 3 phase 208 volts the school used and an obviously broken part of the kiln sitter. No big deal. Of course, after months of talking to the techs at Skutt, discovering with them each call some new thing that was missing, weird things, that make no sense someone would take them off, leading to me needing to rebuild the kiln sitter pretty much entirely as well as some heat switches using bolts so old that it took them weeks to find any in their warehouse. I’m in the process of trying to build my own electronic controller, for obvious reasons but also because I do a ton of glass casting and fusing, and you can’t use kiln sitters with that! I tried really hard to do a Raspberry pi controller from the github creator Jbruce, but after having help from someone on Reddit about what equipment to buy, then not being able to find the new Raspberry pi anywhere for months until I finally found it online only in an expensive package with a bunch of accessories. But I’ve given up, JBruce’s kiln controller GitHub is way too confusing, his electrical diagram is wrong and is missing many things, his list of materials you will need only has about half of what you need on it, and despite watching tons of videos of putting together PIDs on youtube I cannot figure out how the damn breadboard fits into the work box I have, if I need the long breadbox part plus all the little ones that look exactly the same, because no one in the youtube videos used breadboards and the GitHub doesn’t explain anything about how they are attached/wired in, how many that came in that package of different sizes to use etc. I struggled through so many other things with that controller, and was going to do the damn programming of which he seems to have way more of than others I’ve looked at recently, even though I haven’t used python or any code since 2019 and I did bioinformatics for a while which is a lot lot different. Looking everywhere to try to figure out the breadboard thing just caused me to finally throw up my hands in defeat and decide to try and find a less advanced controller, initially thinking an Inkbird before finding out they don’t make them go high enough in temp, damn it. Now I’m on the AliExpress site someone on here mentioned which I’m super grateful for but the only problem is a lot of the PIDs sound good, and will have 32 or 50 step ramps, except it is very unclear with all of them whether there is just one program with all those segments or whether you can save multiple programs, which I would prefer, because not only do I have a couple different ceramic firing schedules but I have a bunch of different ones for glass, and it would be a pain in the butt to have to input them completely every time instead of having at least some of them saved, and if they can have 50 segments you’d think they could have more than one saved program. Seeing your post and your joy with your Raspberry pi controller is now making me rethink giving up, if you are still on here and can tell me which Raspberry Pi program you went with that was so successful maybe I’ll give it another shot. Although I would need to find out about the freaking breadboard. I also was incredibly impressed you succeeded in making your own electric kiln, something I have been told over and over again is not possible. The thing is I make very large scale sculptures, and have to section them for firing and spend days epoxying them and hiding the seams after so no one can tell they were sectioned. I desperately want a huge electric kiln that I could fire my sculptures in one piece. But though I am saving up I won’t be able to afford one for years and years, they are usually well over $20,000. I know your small kiln is not anywhere near the scale I’m talking about, but seeing you accomplish it has given me hope. I also wanted to mention, for all the people who are carving grooves through bricks, that I have been seeing a ton of kilns on social media in New Zealand in particular but Australia and parts of Europe, with kilns with incredibly thick ceramic blanket as the walls with very thick coils of elements attached to the blanket. It is a very interesting kiln look, they have a lot less elements in there because they are so big, and I assume also because it seems that all the insulation is ceramic blanket that they are *extremely* well insulated. If I was to make any kind of electric kiln I think I would go that route after seeing these kilns, and hearing about how they can get to cone 10 at 1220C, which is what I use to get to cone 6 in my IFB insulated American made kilns! I’m a former scientist, although biology related, not something helpful for this like engineering, but it does mean I do have a little more background than the average ceramic artist in some tech stuff. The hardest part for me would be determining all the calculations for the elements, and then being able to get the gauge and even harder coil them to the right size. Otherwise I would just be making a huge ceramic fiber box possibly train style, and just need to hire someone to weld the steel for the outside. And by then hopefully I can afford a proper electronic controller or will have successfully built one hopefully. If I could build my own, I would be able to afford it so much earlier than buying one. That much ceramic fiber blanket will be expensive but a mere fraction of what a commercial one will cost. I just hope I can figure out the elements stuff, having no background in electronics or electricity. I’ve read a lot of kiln books & the chapters on electric kilns are always the same- do not actually write about anything about how they are made, except going into deep detail about the calculations for the elements, then end by saying that you really should never build one and just buy one. So unhelpful, whereas the chapters on all the other kilns are lengthy dissertations on all the ways and designs you can build yourself and how to fire them. In about 1.5 years my plan is to move to France, hopefully to a place where I will have room in my yard/property to build a big enough studio for the kind of work I do, or if I’m lucky have a nice barn or stable to set up in, and soon after I’d like to get that big kiln, and keeps my big but smaller electric kilns as well, and have room for raku and a large pitfire, and also space to eventually build a small fast fire wood kiln and a small soda kiln, under a shelter outside probably. The only way I’d have any ability after spending the money to buy a place & move there to get the big kiln any time soon would be to build it. ‘ And I know everyone will say to me the same thing they said to you, do gas, but I already feel horribly guilty enough using propane for raku, as someone completely against fracking, plus for my large scale sculptures I prefer a true oxidation firing usually, I don’t feel I could get what I want from a gas kiln. And for reduction that’s why I’m building the smaller fast fire wood kiln and soda kilns (also wood), which are much better for the environment than gas. I’ll still probably use propane for raku and feel horrible about it, but I’m not a fan personally of doing my raku electric or with wood, so I’m kind of stuck until they hurry up and invent something to replace it! And I am entertaining gas in a way, because if I can’t get my huge electric kiln built, I will be using Ian Gregory’s flat packed kiln- not the tiny one they show on his website but the huge ones I’ve seen in paperclay books where he is firing sculptures in situ using propane and different sizes and configurations of his flat packed kiln, which is essentially a raku kiln since it is made of panels of hardware cloth covered with ceramic blanket, and clipped together using metal clips like the ones for jumper cables. He consistently got to stoneware temps or all the way up to cone 10 in that, and it would be easy for me to make, cost a little less (and the ceramic fiber could be reused in a big kiln later on if I was able to start building it), and takes up no room in storage since it packs. Flat. There might be some overall advantages to just sticking with that long term, as it wouldn’t take up a bunch of studio space and instead of assistants and hoists and forklifts moving the sculptures to the kiln, I would move the kiln to the sculptures. The biggest downsides for me are that I’d be using a lot of propane with that, instead of electricity that I would also at somepoint be installing solar panels to offset, and I don’t think he got totally consistent temperatures with it always, it is exactly like raku. I’d also be struggling to keep it well oxygenated, although the thought of maybe occasionally doing one of my large pieces in reduction does have some appeal…mostly I just have one form in my head that is huge that would look fabulous in a blue celadon. But those can also be easily faked or I can do SiC celadons which tend to work out for me. Sorry, I went too long. I learned a lot from this thread that I’m grateful for, like it is actually possible to build an electric kiln, even if very small. That I’m not alone in wanting to do that. And a few other tips and tricks…if you read this and can tell me or send me a DM with the github for the Raspberry pi controller you were very happy with I’d appreciate it. I’m super unhappy with the one I was trying to build and its hard to assess some of the others I’ve come across. Thanks!

I don’t think you should look at it as an all or nothing issue, such as replacing all your EPK with ball clay. There are plenty of recipes out there with ball clay instead of or with EPK, it depends on the requirements of the glaze. Depending on how the glaze was developed, there may have been (hopefully there was) extensive testing with multiple line blends or quadraxial blends to determine which of the possible glazes had the most desirable characteristics and that determined the recipe. I’m aware plenty of recipes seem to be just thrown together or are alterations of other recipes, or blending of two recipes (which is such fun to try! You never know what you might end up with!). So hopefully some thought was put into which clay was used, generally the determination should have a lot to do with how much silica and alumina you want and you can adjust that with ball clay without necessarily changing how much flint or feldspar is added. I will say the recipes I see ball clay in I honestly can’t work out usually why they are using it. But your problems that you are having, are not typical of EPK except of course at high enough levels to have excess shrinkage and need calcining. But that doesn’t always solve things, and it may not be your solution. I wouldn’t just jump to trying ball clays instead in these recipes, you’d have to alter the recipes with glaze calc software and people forget that ball clays have an extremely high shrinkage rate themselves, so I don’t know that it would solve your issues. Especially looking over the recipes you shared, the levels of EPK are quite moderate, no where near I would be concerned or recommend calcining. I would be looking elswhere. Any new bags of materials you’ve bought in the last couple of months? Switch to a new supplier? Are you using a newer talc? The other thing I wanted to add is if you haven’t tried CMC with these recipes I would give it a good shot. It will significantly improve the bond between the bisque and the glaze, it literally helps it stick on harder, and tends to help with glazes that are problematic at this stage- we literally use it as a glue in glass fusing and apparently most wallpaper pastes are made out of it! It should help with preventing dried glaze cracks and allow for a smoother application and I think that will maybe help with the crawling. Of course with crawling there are all the typical things about making sure the bisque is super clean, no dust, no fingermarks, no grease to cause the glaze to crawl. It might well help a lot to do a quick dip in water before glazing, that often helps with crawling. I just think looking at your recipes the crawling is not coming form the EPK at all, there just isn’t enough of it to be the problem, so the detective work should shift in new directions. And considering you are having problems with so many glazes…that’s weird. I’m really wondering about any materials you’ve replaced recently. I could see this happening on one or two glazes but not this many unless a material is contaminated…

I know that’s why I said it wasn’t available in the US. Some slips can be picky about their deflocculant and bone china is difficult in general which is why I was hoping it would do find with sodium silicate.

Oh funny, one of the recipes comes from the book Contemporary Porcelain by Peter Lane which I was *just* literally reading in the hospital, I finished it only a very short while ago. I hadn’t had the epiphany yet about stains and bone china, otherwise I would have written those down. Peter Lane’s book blew my mind, because almost every single porcelain recipe in it had a flocculant in it, Peter Lane said that every porcelain body benefits from flocculation, it supposedly makes it more plastic and increases green strength. And it came at a time where I was on the fence about using neph sye as my feldspar in my porcelain recipe, based on the literal rants Matt Katz would go on about using it or Minspar in claybodies in the CMW class, but having been seeing a lot of newer porcelain recipes with it, faced with the fact that the only potash feldspar I have access to right now is Custer, and I absolutely couldn’t bear the thought of going through the effort and pain of building a 6 ft sculpture and then having a big iron spot on it from the Custer. Also Tony Hansen has been extensively using neph sye in as many of Plainsman’s midfire bodies as he can as well as a bunch of opensource porcelain c6 casting slips he is working on- he emailed me and called it “The Feldspar of the Gods”. I’ll DM you what I ended up doing.

Well the last couple of posts provide me with a good amount of hope that synthetic should work, which matches what I know about the biology of it which I think in this case might even be more important than the chemistry of it. It is no problem at all to get as much of the synthetic as I want locally and for pretty cheap if I recall. I don’t even know where to get the real stuff as no suppliers I have looked at so far carry it. I have a surprisingly large number of glaze recipes where I use synthetic bone ash but using it in glazes versus using it in clays like most materials is completely different. I’m excited about the recipes (I have a number of recipes as well that I might try subbing in the synthetic, if I don’t love these first recipes) and hope sodium silicate will be fine as Dispex is not sold in the US. While it might not be as popular as a lot of other things for studio potters, at least having been very immersed in the porcelain world it seems to me like quite a lot of studio potters use it, but that may be two biases- following the careers of a lot of people in porcelain and the fact that many of them are in Europe, where bone china slip is sold by most of the big name suppliers. From what I have seen, it is decently popular there. Especially if an artists starts slipcasting porcelain it seems like pretty soon it is “well why not slipcast bone china?”. I know of a few major artists who throw on the wheel with it, I don’t know if I will pursue a plastic version, if so it would not be on the wheel (I’ve heard even there it has no plasticity) but handbuilding colored clay & I guess I’d see how much you could do with it. I doubt it would get anywhere near what I can build with regular porcelain that has been stained. That’s were I really wish we had Parian over here, because then I could slipcast in bone china and do handbuilt/sculptural colored clay work in Parian, which is so much more translucent than regular porcelain and of course has the self-glazing going for it/surface texture. It might be possible to mostly build sculptures with regular colored porcelain and add some plastic bone china as accents. It continues to boggle my mind how so many parts of the world just don’t have ceramic things that are so common in the other half of the world, including lots of lower middle income countries that often don’t have a lot of the basics. ***Continue reading only if you want a mostly detail-free reason for my feelings about Laguna and how and why I try to avoid them, having found out a few months ago about their huge wholesale monopoly inadvertently but doing what I can to avoid having to personally interact or give my money directly to them: I had a horrible, extremely negative experience with one of Laguna’s clays that I won’t get into but the way the company handled it, their joke of customer service (*one* person who can deal with customer service issues for the whole gigantic LA company who won’t call you back for over 3 weeks, and won’t do the minimum to make things better that every other supplier would do), and their clay techs who make the clay knowing absolutely *nothing*, not even the most basics of basics, of the kind of clay I was using, means I do not want anything to do with their commercial products or to buy from them knowing the hell that would await me if I needed customer service, and a strong aversion to the idea of using their clay after having had horrible experiences with at least two very different clays. I have no control over who buys from their wholesale business and rarely know if a supplier buys from them (I would never have had any idea they had a wholesale business and one of my suppliers buys from them if they hadn’t mentioned it when I asked about ordering some different kaolins somehow) and most of those products are ones they are re-selling so it isn’t stuff they’ve made, I don’t have to deal with them as a company, and I can’t avoid them. C’est la vie, like most monopolies you might try and boycott they are everywhere, hidden, so you can’t really avoid them. I’ve accepted that but I can still avoid what I can control. I will be doing whatever is in my power to avoid their talc especially considering Matt Katz has tried it and says its awful. Sorry to go off topic but you seemed especially to be trying to say something about my refusal to buy from them.

I’m not sure where you read anything about my life, but that has nothing whatsoever to do with my post about Simon Leach, which was clearly a gentle poke at the man in response to people saying he is just so utterly soothing and comfort food and it was clearly a joke. But it was also just a different experience with Simon Leach where he is very influential with some things, hundreds if not thousands of people have been influenced by him to convert their kilns into gas kilns, that is some serious ability to influence people. Hardly just the equivalent of a cup of soothing tea. I’m sorry that you could not recognize the joke, I in no way slammed Simon Leach or as you are implying are taking out anything from my personal life out on him! I have to say I feel a bit offended that you used whatever knowledge you have of my medical situation to let it influence how you perceived what I wrote, assumed that it influenced me with my writing in any way, and frankly if you know the severity of my medical situation saying something like “let’s focus on on the positive, what videos do you recommend” is rather offensive. It is not for you to tell me when I should feel positive or assume that I wasn’t completely feeling positive when I wrote that post, as if listing videos I recommend is going to fix my legs and my genes by thinking positive right then!. Maybe consider being a little more sensitive next time, don’t assume so much, and consider whether you should take out your sense of humor when reading a post.