Callie Beller Diesel
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Posts posted by Callie Beller Diesel
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17 hours ago, yoony22 said:
I read somewhere you can use baking soda to make this rough stoney texture. So can you mix any glaze with baking soda? And does it need to be fired again?
So that piece looks like it’s just in the bisque stage, before any glaze has been applied. Or it may be fired to maturity, and they just didn’t put glaze on it at all. That effect could be made with any light coloured clay that has had some sort of sand or grog added to it for texture. I have never known baking soda to specifically cause that texture, especially if mixed into a glaze.
17 hours ago, yoony22 said:Is it achievable with special glaze? Or is it stoneware?
Possibly both. Matte glazes aren’t uncommon at medium or high fire temperatures, and are reasonably straightforward to formulate at those temperature ranges. I believe there are commercial matte glazes, but I’m less familiar with those. They’re not special in the sense of rare.
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Sharp rim, and think about having the fluid go from an area of low concentration to an area of high concentration. That is, having the spout not be too wide in relation to the volume of fluid going over the edge.
If all else fails, put a smear of butter underneath the rim. Hank Green did a short video on it sometime last year.
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+1 for that being a hot cone 6, possibly a cone 7 where the second cone pack was.
Others have addressed the heat and speed thing, I just wanted to add that if you make your cone packs out of fresh clay, it’s doable. Adding some sand or grog to the clay can help them dry without blowing, as will poking a bunch of holes in the clay log with something like a fork.
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My impulse is also to think it’s uneven drying, especially since you mention a thick base to start with. If your wareboards aren’t the absorbent kind, flipping the pieces upside down as soon as they’ll support themselves and drying upside down after trimming may help. If your cross section is uneven, that will contribute, so your idea about the tombo for a foot ring could be the ticket as well.
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Fun fact: Canada doesn’t make pennies anymore, although ours were all copper.
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If it’s bone dry, usually glazes or underglazes will slake down quickly with a bit of hot water. I don’t know what might be in bisque fix that could change that, but it seems like a good place to start.
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ah; the stink of reclaim! Yep, it’s gross.
The black streaks are nothing to worry about. They don’t hurt the clay and it’ll burn out in the kiln. Don’t worry about trying to remove it from already wedged clay.
For the throwing water, we’re probably going to tell you the same thing as Reddit and other replies on this forum. There isn’t really a measured amount or proportion of peroxide or bleach to add. Start off with a small splash, (a few tablespoons) and add more later if it still stinks.
Some of that is because the quantity needed will depend on how much mould is in there, what you use and how mould friendly your conditions are.
I wouldn’t use Epsom salts: I don’t think it’s particularly antibacterial. I favour peroxide because it breaks down into water, but if I don’t leave my reclaim sitting long, I don’t have to do it much.
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On 5/30/2024 at 9:57 AM, falseawareness said:
How did you organize every day technical details? i.e. this is ready for bisque fire, glaze fire, needs more work, focus on this detail.
This question in particular is very specific to a given situation. How I manage my own workflow for getting ready for shows is different than how I cycle work through kilns for the teaching studio I’m at.
In general, you pick an end point (eg, a show you need to make work for, or the end of a class) and work backwards to make your plan. If I have 6 weeks to make $8K of work and have my booth setup ready and photos taken, I know I’ve got about 3-4 weeks of wet work, a week of glazing and firing, and a week of booth prep (rough example). There’s different admin tasks that have different end dates, and you still have to factor still others that happen less frequently, like quarterly tax filing. Most folks I know do a very rough layout for the year sometime after Christmas, and flesh out more details on a quarterly, monthly and weekly basis.
With the teaching studio, I’m laying out all my bisque firings based on when that class is glazing. We have something like 12 instructors with 1-4 classes each, starting on a rotating basis. Classes are 6 weeks long, except for wheel samplers, which are the “make your first pot” evenings to give people a quick, fun taste. I mark out the end dates of each class on a big wall calendar, along with their class stamp to identify pieces by. All work is sorted by class stamp after bisque and glaze. The deadline to have a class’s work in the bisque is 4 days before the last class, which is glaze day. Glaze firings happen when we have enough to fill a kiln (about every 2-3 days right now). Member work and wheel sampler stuff is loaded around class work, but everything moves through pretty quickly, as no one class will fill a kiln by itself. We try to have classes wrap up at different times, but some weeks are still more bisque intensive than others. So things like monthly glaze bucket maintenance are tackled on quieter weeks.
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I’ve worked in a few different group situations over the years as well as being on my own. I went to university for clay, so that was a student/teacher situation where I was the student, but I’m now working at a teaching studio as an instructor and the glaze tech. I’ve also worked in group studios where people just rented space and worked independently. I’ve also spent a lot of time with a studio in a garage or basement, and I transported work to fire. I know others who work as solo potters, but I also know several who work with a spouse in a more collaborative studio style. There’s good and bad points to each situation, and it’s kind of up to you what you need the most at a given point in your career.
The pros (not exhaustive) of working in a group studio or teaching situation:
-you can bounce ideas off of other like minded people
-having an external workplace to have to go to leads to a more healthy work/life separation
-you can share assorted studio tasks so your entire time isn’t taken up wth managing a big space all by yourself
-organizing to order materials in bulk usually leads to savings
-being exposed to things you don’t do yourself can lead to a lot of creative and practical skill growth
Some of the cons:
-you can sometimes get really distracted by your fellow clay people and not get anything done
-more people moving stuff leads to more opportunities for stuff to be broken or damaged accidentally
-you need to have strong communication about cleaning/expectations or there will be resentment/fights
-you might be restricted in your work by the available kilns or glazes; lack of flexibility in firing schedules
Some pros of working by yourself:
-complete creative control over kilns, firings and other materials (no undesired clay cross contamination)
-you can leave things out and come back to them as you will; no one will be after you to empty your splashpan
-room to screw up/be vulnerable in private
-you can crank your tunes as loud as you want (or work in complete silence)
-alllll the shelves are yours!
-pieces are vulnerable only to your own level of clumsiness.
-if your studio is in your home, you can do things like flip pots before bed, or unload a kiln first thing in the AM in your pj’s.
Some Cons of working by yourself:
-you are responsible for everything. All the cleaning, all the firings, all the maintenance, all the costs.
-at some point it becomes isolating. You have to make more of an effort to be social.
-no one to encourage you or commiserate with if you knock over the board of pots you just filled.
-learning and feedback opportunities from other makers are much more limited, and must be sought out purposefully
-no work/life separation if your studio is in your home/on your property
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Frit 3134 can also be useful if you need to make room for more alumina to be supplied from clay. It’s very similar in composition, but with less alumina. I think I read somewhere on digitalfire that it was formulated to do just that.
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Dealing with commercial glazes makes things a bit tricky, because we don’t know what’s in them, or the exact mechanism they’re using to create a matte, but it’s not impossible.
If your supplier has a matte and a gloss glaze that both come in dry mix, you could try combining them in different proportions to get the finish you want. Start with 80% matte and 20% gloss, +/- 5 and 10% either side. As far as making it more off white, you could try adding small percentages of rutile to warm it up a little.
When adjusting white glazes, make sure to use larger test tiles than you normally would. A small square of white glaze will look much like any others, but when you apply them on even a 250g cup you’ll start to see the subtleties. Things like how much, or even if it breaks and pools, what colour does it break, are there any glaze flaws evident, how much does thickness of application matter, etc.
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I think it’ll depend on the area, but unless you can get very cheap real estate, having your own brick and mortar store isn’t going to be anywhere in the same cost category as wholesaling or doing shows or selling online, or anything else.
Also, running your own store is a different job entirely than making pots and selling either direct to customer or via wholesale/consignment. I don’t do much in the way of wholesale, as there’s less demand for that in my area. I decided at the start of the pandemic that I couldn’t afford to do consignment, as the work tends to sit for too long before I get compensated for it.
That said, @Magnolia Mud Research has a brick and mortar on their property I believe, and @Mark C. Has a lot of experience with wholesale. Hopefully they can give you more specifics.
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Yes, but it can be a gross oversimplification to think of just swapping out one flux for another just to get silica and alumina to melt.
Info like that is mostly important for making sure you’re not using too much of a given thing, or making sure you’re using the right proportions of it to fire at the temperature you want. And even then, you have to consider that info in context of how it reacts with the other materials. They’re not interchangeable like that.
Subbing Ba for K was probably an arbitrary choice, but I’ll use it anyways to show the kinds of considerations that also come into play, even though this is an unlikely scenario.
For starters, just on the numbers side, you’d be altering the flux ratio because the 2 are in different categories. This will alter things like the colour response and the fit of the glaze. And possibly some aspects of durability.
There are also no sources of potassium that I can think of that are separate from at least a little bit of sodium. Most often it comes from feldspar, and if you remove the feldspar, you’re also taking out silica and alumina that have to be made up somewhere else in the formula. And the sodium, assuming you want to keep all other ratios the same. That material substitution is going to affect how this glaze behaves not only in the kiln, but in the bucket. How a glaze applies to a piece affects how it melts, and how it looks in the end. We’ve all seen glazes that look different when thin vs thick. Things like how the different sized or shapes of particles also affect how a glaze melts, and can affect things like micro bubbles or pinholes. Or lack thereof.Then you’ve got individual material properties. Ba used in excess (think 20% by weight) actually does have a very lovely and interesting colour response. When used like that, it makes matte glazes that break and pool 2 different colours (think pink and blue combos) in high fire reduction. However some of those glazes are so soft you can scratch them with a butter knife. Plus they leach. That’s an extreme example, and a few percent to compliment other fluxes still gives nice flow, can clear bubbles and still offer vibrant colours.
If you’ve made it this far into my answer without nodding off, I believe there are some charts in Hamer and Hamer’s The Potter’s Dictionary of Materials and Techniques. It’s well worth the price tag if you want to get into more of the chemistry.
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It’s also worth noting that there’s some wiggle room in how “melt” is defined. Materials fuze and then ooze over a range of temperatures. For instance, some glazes are matte if they’re underfired, but are properly a gloss with a bit more heat work. Yet others develop matte surfaces with additional heat work, because the assorted components need time to form a crystalline matrix. There can also be noticeable changes in colours or other surface qualities if a glaze is “over” or “under” fired. And what one person finds aesthetically pleasing someone else might hate.
Leaving aside durability issues with the first example, the desired finish point of a glaze is determined in part by how you want the finished piece to look. -
What I’ve noticed about flocculation in general is that either bentonite or epsom salts alone work a little, but the 2 together work better. Personally I’d rather have enough clay in the recipe and use the epsom for suspension. I dislike using bentonite because dispersing it properly is a nuisance. I don’t find the drying time from Epsom to be a problem with my workflow, but that’s a personal preference.
If the 4 % bentonite works for you, there’s no need to fix it. It’s just a different solution to the problem of how to keep non-gerstley glazes suspended . -
I can use some real numbers as examples so it’s maybe more clear.
If you want 1kg (1000g) of your glaze and the ball clay is 20% of the recipe, there’s 200g total of uncalcined ball clay.
The low math version involves weighing out half your ball clay (100g) and calcining it, and adding it to your bucket with the other 100g of uncalcined ball clay.
The more math version:
I don’t know what you’re using for ball clay, so I’ll use OM 4 as an example. According to Digitalfire, the loi for that material is 9.3%.
So assuming you had already calcined some ball clay and just needed to weigh it out, you’d use 100 g of regular ball clay and 90.7 g of the calcined stuff for that same 1kg batch using adjusted materials.
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+1 for the clay being the problem, not the ash. Or at least less the ash. Glazes with clay in them also shrink when they dry, not just your pots.
Another idea would be to calcine part or all of the ball clay if you don’t want to change any materials. You will have to do a little math to keep the proportions the same, because the calcined clay will weigh less than the raw, but will be supplying the same amount of oxides.The low math version of doing this involves weighing the clay you want to calcine, fire it and add it to your glaze bucket. eg, if your recipe has 20% ball clay and you want to calcine half of it, you’d weigh 10% to be fired first and the other 10% as usual.
If you want to figure it out by math, you’ll have to look up the specific LOI (loss on ignition) of the brand you’re using and reduce the weight of the calcinend portion by that amount.
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I wanted Glazy’s target and solve for something, so I sprang for the membership for a year. The paid version lets you overlay the common limit formulas over the Stull chart. It also lets you overlay the Montmollin fuse charts, which is less helpful, but I digress.
The limit formula overlays are a nice visual. If you’re not at the place where you want to pay a bunch of money for glaze software, I’m happy to screenshot here for educational purposes. -
3-4 bentonite seems high. What’s the other clay content like in your revisions, and are you using epsom salts to help keep things suspended?
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As someone who chased this particular dragon: no. I played with formulas and firing cycles, and you’re always left with at least some micro bubble clouding.
Min’s right about the best way to make a glaze look clear over a dark clay body being an amber. If you want to play with marbling, you could try using a buff clay instead of the white.
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@Magnolia Mud Research you might be on to something there. The weather has started warming up, so we’ve been opening the back roller door to allow for more evaporation off the reclaim barrels. On the days we’ve been ove 20 degrees or so (that’s 68 for you fareneheit heathens), there’s been a noticeably larger amount of clear water on top of the barrels. It was only an inch or so, but it was noticeable. The warehouse bay’s thermostat is set to 19, but it feels cooler than that.
So given that I have 2 options available for possibly heating some slip: a metal bowl in the test kiln or a plastic container in the microwave, which one is going to make my boss question my sanity the least? I’ll let you know.
@High Bridge Pottery this might tie in to some casting slip principles too. Don’t slip densities change with temperature? I can’t remember what the range is though.
Wax/sticker resist
in Clay and Glaze Chemistry
Posted
Industry has a lot of things available to them that small scale potters don’t.
I would imagine they either stamp or screen print the wax on, and adjust their glaze viscosity carefully so that the glaze flows off cleanly.