Callie Beller Diesel
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Posts posted by Callie Beller Diesel
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A few years ago we had a contributor @liambesaw, who had ventured into making his own lustres, which admittedly aren’t china paints, but are related. He didn’t detail a lot here, but I do recall he built himself a laboratory fume hood in his back yard because the process created a lot of stuff that’s really bad for your health. So there’s probably some solid reasons for manufacturers taking over the supply end of things.
That said, I do have an addition to the china painting resources. Melanie Sherman is an artist that offers both recorded and in person workshops on the subject, and at the time of writing, the recorded ones seem pretty affordable. https://melaniesherman.com/melanie-sherman-ceramics-workshops/
Again, at time of writing, she seems pretty approachable to questions about the craft.
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Remember that just because a glaze is matte once fired, that doesn’t mean it isn’t fluid in the kiln. So re-melting it with a layer of underglaze is going to melt the underglaze into the surface of the first layer, which will probably leave a bit of a half melted surface. If you throw another glaze on top of that, you’ll be creating something called a eutectic, which is a fancy way of saying the 2 glazes are going to steal materials from each other in a way that will make them melt even more actively than the 2 do separately. This effect is usually more pronounced when you combine a matte and a glossy glaze.
Could this be interesting? Maybe. Depends on the context. Could be a really interesting sculptural effect, but something that’s wildly impractical on a functional piece. Could this make a mess in the kiln? More than likely. If you try it, use a waster with a lip that can contain any runoff, and make sure the person firing the kiln is ok with you doing this. Will this fix a mug? Doubtful. But if it’s already wrecked, gaining information is a worthy endeavour.
If you just want a mug that works, it’s going to be way less time consuming and frustrating to make a new one.
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Hi and welcome to the forum!
What I’m really finding in my own testing is that colourants have a much stronger affect on the possible durability of the end result than is often assumed. I had a similar experience where a base glaze has pretty good numbers on paper, but certain unexpected colourant additions made some tiles fail a vinegar test (iron!?). My flux ratios and silica balance are similar to what you have listed, and I’m currently running some line blends to see if I can keep the same colour response while increasing the silica for durability.
Dishwasher tabs do contain a lot of alkaline chemicals, including sodium carbonate (soda ash), that will etch all dish ware over time, not just pottery. It dissolves the silica. So testing ware in a way for dishwasher durability in a short amount of time that isn’t also too heavy handed is tricky, I think. I think the digitalfire recommendations that it looks like you followed may be too harsh.
I’m going to tag @Minbecause I think she had different recommendations about the concentration of the soda ash solution, but I can’t remember the numbers she used.
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I only found the pencil thing happened once at cone 10, and it was under a specific glaze that I didn’t know could carbon trap.
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Use India ink on the larger crackles, and soak them in tea for the secondary pattern. Apply the ink when they’re freshly crazed out of the kiln, and then do the soak a few days later.
- Magnolia Mud Research, Min, PeterH and 1 other
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About the only thing I can think of to add graphics that will stay would be to add decals or underglaze/slip at the usual leather hard/green stage and bisque it on before the pit fire. It won’t guarantee the ash and other stuff won’t mute or blur them, but that could look pretty cool.
I didn’t do enough pit firing to be able to dial in specific colours, so someone else is going to have to weight in on that part.
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Sand or other temper like grog, chicken grit, large mesh feldspar, etc will indeed make a clay body less plastic.
As to the clay body pictured, I think the colour has less to do with the underlying material and more to do with how it was fired. If I had to guess, I’d say it was pit fired. That’s if it’s clay at all.
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The least intuitive part of collaring is the part where you have to speed up for it to work better. Other than that, some things to keep in mind are to make sure you do a small pull or a pass with a stiff rib in between collaring passes.
- Hulk, rox54 and Magnolia Mud Research
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Cracking can have a lot of reasons. If you find your reclaim is cracking more than fresh clay and all other forms of user error have been eliminated as possibilities, there’s 2 possibilities that come to my mind.
First, it could be that the reclaim has more throwing slop/fine particles in it. If there’s no trimmings or dry bits added to it, or you’re just drying the throwing bucket leftovers on the plaster wedging table overnight, you wind up with all the stuff that is plastic, but also shrinks a lot. If this is the case, save your throwing slop to add to larger batches of reclaim. If you don’t wind up with a whole lot of reclaim, you can repurpose it as decorating or casting slip. I know a lot of us feel strongly about waste, but it is ok to discard some in the trash if you really don’t have another use for it.
The other possibility (and I experience this with Plainsman M390) is that it may be a clay body that really needs to be slurry mixed to get useable reclaim. Some clays have a diverse particle mix, and if they’re not blended well, you wind up with issues.
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Hi and welcome,
I’ve moved your post into the buy and sell section, so it’s easier to search. Some more details about the kiln would also be helpful, such as the size and model number off the plate, as Cress and other manufacturers usually make several models of kiln. If you need assistance uploading a photo or 2 that shows the state of the brick and the elements, those are usually the most helpful. If you need help resizing, don’t hesitate to DM me and I can assist.
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@Shark Easy is subjective. I personally have no problems adjusting glaze flow, but we’ve also heard from lots of folks who feel otherwise.
Adjusting glaze flow does take practice and it can be easy to mess it up, especially if there’s a lot of different solubles working on the glaze slurry. While the conversation here started going towards more processed materials, the OP specifically referenced a very soluble form of household borax. It can take very little material to accidentally over-deflocculate a glaze and turn it into a completely congealed and unusable mess. And then your materials savings are gone, because you have to throw out the batch.
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Hi and welcome to the forum!
La mayoría de los miembros del foro son de habla inglesa, pero tenemos muchos colaboradores internacionales. ¿Tiene software de traducción en su navegador o le gustaría algo de ayuda con eso?
It all depends on how much barium you’re trying to replace and why it’s in the recipe. Large amounts of barium can be used to create a matte surface, and it also gives some glazes a distinct colour response, especially in reduction firings. Are you able to share the recipe and let us know what you need the glaze to look at?
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Another avenue could be to add some zircopax to the recipe of your choice. Usually you don’t want it in a cobalt glaze because cobalt is pretty opaque by itself, but if you have a base glaze that works in all other respects, that could serve to get rid of any pooling.
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Hi and welcome to the forum!
Pinned at the top of the Clay and Glaze section of the forum, we do have a list of articles and websites on processing wild clay, as it’s been a pretty popular activity in the last year or so, and lots of folks have been asking. Here’s a direct link.
If you’re dealing with a smaller seam of clay in your yard, it’s possible there’s a mix of a few different clays with different properties. If you want to use it regularly, it’s worth digging the amount you think you’ll need and slurry mixing it thoroughly so you get consistent results.
At 1250 C (cone 6) feldspar should be behaving like a flux in a clay body, not a refractory. Kaolin doesn’t usually have significant amounts of sodium or potassium, so if you need your clay to warp/melt/bloat less, that would be a good place to start.
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I’m not one to throw a lot of teacups off the hump, but I do all my jar lids like that, and I never get s cracks. I make a shallow form with a large “foot” that gets trimmed into a knob, so there’s some similar principles at work I think. I’ve used this method on lots of fine toothed clay bodies, including B-mix which can be notorious for this kind of thing.
I try not to throw with too much water, or let it linger at all in the bottom. I don’t spend time going back and fort across the bottom of the pot, but for lids I do use a flexible metal rib to get the curve I want, and to remove all slip. I use a heat gun to stiffen up the rim enough that it won’t adhere to the jar gallery and let the pieces dry together for most small jars, but larger ones I’ll let stiffen up for a couple of hours before I put them together. Doing this makes them dry very evenly because of the trapped humidity on the inside of the jar. I almost never have to cover them overnight. Unless the weather is unusually dry, if I throw them sometime in the afternoon they’re ready to trim the next morning.
For teacups, to replicate something similar I’d just flip them as soon as they’ll hold up to it, and let them dry upside down after trimming if the problem persists.
When I trim them, they also get a good burnish on the knob side of the lid with a silicone rib at the end. This step is for aesthetics and might not contribute a lot to crack prevention, as I didn’t get them before I started doing it. But maybe worth a mention
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Thank you for the updates! We always love hearing how things turn out.
May the firing go well.
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Just an addition to Min’s comment, as we’ve been having copyright discussions in relation to other things. You can type out the recipe, and you should give proper accreditation, but you shouldn’t post photos of the book page it’s on.
- Min and Kelly in AK
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I’ve also found that having a shipping included price on the website eliminates confusion. I never use the words free shipping, because shipping isn’t free, and especially in Canada you can’t afford to just eat any part of it.
Back when I had my etsy shop, they were beginning the push for all vendors to have “free” shipping. I was annoyed with the whole thing, and thought that people were smart enough to recognize that shipping charges would be extra, and that it wouldn’t affect buying behaviour. I was so annoyed, I decided to run a test in my own shop just to prove it. I made listings for my mugs, some with shipping included and some without. I wound up eating crow, because people absolutely bought the $60 mugs over the $40 + $20 mugs.
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The maddening answer to just about everything in glazing is “it depends.”
IF it’s available to you, clear glazes are usually much easier to apply thinly and evenly via dipping. If it’s not, then brush away.
If you’re mixing 2 glazes, this can often result in special effects that are partially due to running. When starting out you might only want to apply 3 layers in total, however you want to divide it out. Usually you don’t need a clear glaze over other glazes, unless you’re hoping it’ll do something interesting. If that is what you’re going for, make sure you have a waster or a cookie under your piece to catch any drips. Cleaning kiln shelves is not fun!
Learning how to apply glaze is another skill that takes experimentation and practice to get the hang of, and it’s a good idea to do some test tiles before you start glazing your favourite piece. Recommendations on the label should be considered starting points. Your idea of a thick coat and someone else’s might not be the same thing, and you have to play around with it a bit to find your sweet spot.
Generally clear glazes want a thinner application than other things for best results. An overly thick clear glaze will go a bit cloudy. This effect is more noticeable on dark clay or underglazes than it is on lighter coloured things.
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Some clay bodies tend to not like being refined multiple times like that, especially if they’ve got a bunch of free silica that hasn’t been taken up by other oxides in the melt. You have to baby these clay bodies through quartz inversion accordingly. So +1 for everything already said about foot rings, kiln packs and firing speeds to get pieces through that zone more evenly.
- Rae Reich and Kelly in AK
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Some of it will also depend on the recipe of the glaze. The various flux materials can have different effects on some colouring oxides. For instance, if you put a copper wash over a white clay body, a clear glaze with a lot of sodium will give a more blue turquoise. But if the main flux is boron, we’d expect it to tend more towards green. Manganese might have a more purplish tint to the brown if there’s a lot of calcium. Things like that.
I wouldn’t expect a wash that’s over a glaze to react with a wash applied under the glaze, unless the glaze is especially thin or unless the glaze firing is especially long.
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If you look on the MSDS sheet for the toner you’re using, it should mention an approximate level of iron oxide. I’m a bit rusty, but I think that the levels could range between 15 and 35%. The higher the concentration, the better the image will hold up.
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If I was going to try to get a similar effect and I was using moulds, there’s a couple of ways to go about it.
You could start with thin layers of the light coloured slips to line the mould, possibly brushed or airbrushed on unevenly, or even just very thin pours (2-3 minutes each). Next, there’d be a layer of black slip, and then do the full cast with the unpigmented casting slip. Once the piece is removed from the mould, it looks like some kind of abrasion happens, whether through using a trimming tool or a metal rib to scrape off some layers, or sanding as others have mentioned. I’d be more inclined to do that work when the piece is firm leather hard to reduce dust creation than to sand, but I hate wearing a respirator more than strictly necessary.
Because it looks like she’s slipcasting a textured cup and then layering other colours on top, it looks like she’s putting a black slip or underglaze layer over the whole piece, and using 2 other layered complimentary colours (yellow and orange, blue and green, pink and red) over the black. After that, again some form of uneven abrasion.
There’s a few artists that layer coloured slips in the mould and do different things to reveal the layers.
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If it’s thinner than 2mm then the principles above are even more applicable. Annealing, torching and annealing is sounding like the ticket. I’ll also ask a glassblowing friend to see if she’d be willing to advise.
QotW: How often do you vacuum out your kiln and sieve your glazes?
in Int'l Ceramic Artists Network (ICAN) Operations and Benefits
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Vacuuming my kiln: I plead the fifth. Don’t do what I do, kids.
Sieving: definitely as I make them, and if they’ve been sitting for several months unused. That latter doesn’t happen much anymore, but worth mentioning. I try and keep my buckets clean and wiped down because sieving usually winds up with more on the floor than I want.