Callie Beller Diesel
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Posts posted by Callie Beller Diesel
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On 10/31/2023 at 10:08 PM, Clay Wallower said:
They came back not at all like what I expected.
This may be the single most eloquent statement to ever describe working in clay. Welcome to the experience, and I’m sorry in advance!
There’s always more testing involved in getting a specific, desired result, but the payoff can be worth it. I agree with everyone above about firing to a hotter cone to start with, and making multiple tests with varying layers of glaze to find your acceptable working range.
However if that doesn’t fix it, I do notice that the more green range of colours on the chart with the different clay bodies were on the more darker or speckled clays. You could try a light iron wash over your existing clay once it’s cast, rather than trying to switch clays. A-mix and your chosen porcelain slip are both very light firing, and I can’t think it’s entirely unrelated to your results.
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If you can’t convince the principal to get a kiln, there are lots of hypertufa or Cobb projects that could fit the bill too. Let them see that in action, and a kiln might be an easier sell.
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I’m going to tag @Pres, because he’s a retired art teacher and can speak to the technicalities better than I can.
I’m not an educator myself, but I can personally speak to the fact that working in clay taught me chemistry and physics. Glazes are high temperature redox reactions, and the practical application of that made the need stoichiometry calculations make some sense.
Clay and material knowledge are a cheap and cheerful introduction to structural engineering. It teaches observation and perseverance. It teaches planning. All of which are highly useful skills for most people.
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Lol! They’re more known here for pottery supply. At least outside the movie industry.
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The flax fibre may just be an availability thing. I used cotton linters because they were stocked in the bookstore for a paper making class, they were relatively cheap, and while they were considered short for papermaking, they were a long fibre for paper clay. I can’t remember if flax was available or not, but I remember discarding a number of other available plant fibres because they were too long for the purpose, more costly or both.
Lots of folks will fine tune a material if they use it extensively and develop preferences, but for repairs, starting out or occasional projects, using old newsprint or tp really does work a treat.
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Step one would be to get a lead testing kit if the piece is older than about 20 years. Amazon sells them if the local hardware store doesn’t have them.
You may have to go with both a chemical stripper to remove the paint first, and then fire the piece to 800 F to remove that residue, as Bill mentioned. Many paint pigments are mineral based, and in the event that the paint contains any lead, that would act as a flux that would make any residue permanent. Paint disposal and proper kiln ventilation would also be important considerations
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Hi and welcome to the forum!
I’m reading this as the brown/beige substance being the stuff that’s seeping under your resist. If you were using a brushable cold wax as your resist, it could be that the wax just wasn’t dry enough before you applied, or it just wasn’t sufficiently saturated into that fine texture (which looks really cool, btw).
If it’s really important that the beige glaze be removed entirely, some kind of brush may be necessary to get into all the crevices, and you’ll likely remove the wax and white glaze in those areas as well. If the wax is applied over a layer of glaze this is going to present fewer problems than if the wax was on the bare clay, as the first glaze will take the wax with it. You’ll want to let the piece dry thoroughly before attempting to reapply.
Depending on what colour the beige glaze fires to and what’s in the white glaze, removing every trace may not be necessary, but it depends on what colourants are in it, and how saturated it is. The watery shadow of some residue may be overpowered by the other glaze.
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In a group studio situation, it’s always best to consult with the tech there, to see how they want to handle it as well. They may have rules or suggestions.
- Rae Reich and Kelly in AK
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Any refire temperature will depend on what temperature the clay and glazes were used the first time, and what you want to use now.
I’m a bit confused about why the piece is getting brittle over time. Was it fired in the first place, or ?
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You can stave off some bacterial growth with bleach, but it’s hard on the hands. I’ve seen others recommend things like Dettol, but it really is best to make up what you need, use it within a week or 2, or store very thin bone dry sheets that you re-wet. When I was working with it, there were no commercially available paper clays, so I have no idea what manufacturers use as an antibacterial agent.
The re-wetting thing is indeed very cool to observe and play with! It gives you a lot of flexible ways to work.
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I’ve never heard of anyone complaining about the Aftosa wax, other than possibly about the price, or the fact you have to mail order it in some areas.
If it’s not doing the job for whatever reason, the only alternative I could think of that won’t freeze would be soy wax. It melts at a MUCH lower temperature than paraffin or beeswax, so flinging it with a tool shouldn’t be a burn risk the way the other 2 would. I wouldn’t use a brush with any melted products, or at least not ones you want to use for other purposes.
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Dragon Fruit is an IMCO product that can be purchased at the Plainsman outlet in Victoria. I can’t get it in Calgary either, sadly. (I only mention it in case anyone else goes looking for the SDS).
Granular Illmenite tends to fire a more tan/light beige brown colour in cone 6 ox glazes, not the darker brown of manganese. It does tend to show better in reduction. I have no idea how it would turn out in a clay body. It’s a titanium mineral that has more iron than rutile does, so I don’t know if the chemical decomposition is going to be less than the Mn. I don’t think it would show well if you’re adding it to a darker clay body, but it might on a lighter one. You’d really have to do a small test to find out.
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Adjusting bottled glazes is tricky, because in addition to not knowing what’s in the recipe to start with, they add gums and brushing agents that change how a glaze dries. Adding material can affect how well those things work, because you’re diluting them. Some commercial dry glazes will have them, some won’t. Usually if a manufacturer doesn’t recommend sieving or recommends minimal mixing, or specifies the amount of water to use, there’s some suspension agents or gum of some kind.
This is not me trying to dissuade you, it’s only things to keep in mind as you test. All things are possible if you have the time and energy to figure it out. It will just be easier to adjust a dry base glaze from Plainsman (who provides the recipes of their base glazes) than a bottle of Mayco.
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SIAL is in Laval, which isn’t too far from you. They have dry glazes from Mayco and Tuckers listed on their website, as well as a clear from Laguna. They carry Plainsman clay, so it might be possible to special order any of those dry base glazes and add stains or oxides to colour them.
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I think the first step would be to identify what you want the storage and inventory system to be able to do, and what about your current setup is working and not working. Also, we need to know what you have to work with. Do you have a dedicated space that is art-only just needs reorganizing or are things scattered in different areas and is next to your Christmas decorations? Is it convenient to access and do you need it to be? What kind of things are you storing and why? Someone storing sculptural pieces long term for eventual collectors or galleries is going to have different requirements than a potter storing work between shows.
Answering that before you even start taking inventory is important, because I’m going to suggest setting aside a day to set up a photo station and documenting things as you take inventory, and what else you need to record will be informed by that.
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1 hour ago, Summerss said:
Laguna recommends not to fire the cone 6 clay past cone 5.5.
Laguna 50, and any other clay body with manganese speckles tends to experience bloating if you go much hotter. It’s not the clay itself, it’s the manganese granules breaking down and creating gasses that form pockets in the clay, or may contribute to pinholes and blisters in glazes.
If you want to understand what happens to clay inside the kiln, start with this digitalfire article. Any terms highlighted in blue are outbound links to definitions or other articles that will explain things in more depth. There’s also more links and definitions stuff at the very bottom of the page. Cannot recommend this one enough to beginners.
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Can you let us know which one, and the glaze as well?
Most suppliers put their information online, and google translate is pretty good in the event the specifications aren’t already in English. More information would help us give the most practical answers.
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If the piece is collapsing that drastically, it’s not the size of the grog or the amount of it you’re using, it’s how much the clay that the temper is in is melting. You said this does not happen with earthenware, which is usually not fired to the point where it begins to melt as much. You did not mention if you used a porcelain or a stoneware to make this piece, or what the product specifications of it are. If the clay is not meant to be fired to the same top temperature that your glaze is, you will have to change the clay to something that is. Or fire it with a support of some kind, much like you have it propped on in the first picture. The movement in the work in progress image has a lot of movement: using the kiln to create some more could be an interesting idea.
Partial glazing of large pot in soda fire
in Clay and Glaze Chemistry
Posted
It sounds like at best, your tech is either grossly oversimplifying his explanations, or he hasn’t done a lot of soda firing. Or both. My wood fire and soda mentors all experimented with how different kaolins, feldspars and fuel types affected flashing slip recipes. The differences are indeed noticeable. Clay body also matters.
It is possible, under fairly specific circumstances, for a glaze that fits a clay body to pull apart a piece that’s only glazed on the inside. But the glaze has to be as thick or thicker than a relatively thin clay layer, and the piece in question is usually a wide flat piece with right angle walls. Often in this example the glaze will involve lithium as an ingredient. It does non-standard expansion things.
These are not your circumstances. These circumstances largely don’t occur in soda firing. I won’t say never, because we all know (or have been) That One Kid who did that thing once that still gets talked about.
If the walls of your pot are thicker than the glaze, which I would expect to be the case with a piece 3’ tall, you’re fine.
If you want to highlight the texture of your piece, I think a light spray with flashing slip and carefully choosing the position in the kiln is a great idea. Sodium reacts with the clay body itself to form a glaze, which means that areas that are heavily exposed to the vapour can have sharp textures blurred. So you want to have the piece placed somewhere that won’t get fully blasted, but will take advantage of flame path depositing the vapour.
I suggest you’d want to avoid right in front of any soda ports if they’re spraying, or right in front of the bag wall if they’re dumping burritos or soda plaster lumps into the firebox. In either case, you also don’t want the piece to be right in front of the flue exit, but to one side of it could be interesting.
If there’s any salt in the mix, all bets are off and you’d need to ask someone very familiar with the specific kiln where the “wet” and “dry” spots are.
Soda by itself tends to be very sluggish in the kiln, which is why people either spray it, or mix it with water and something like whiting or sawdust that will help it disperse from the firebox more easily. So you can get some pretty pronounced flame records on soda fired pots. Salt will more or less explode when it hits a hot kiln, so it’s easier to get a more all-over coating, and it’s why it tends to take less salt to get an orange peel effect. A few soda artists of my acquaintance aren’t afraid to refire pieces that didn’t quite get the coverage they wanted on the first round. Most kiln bosses will prioritize items on their first ride through the kiln over re-fires though, so check with whoever’s firing the kilns what their preferences are.