This assembly is the bottom half of a 3D printed 0.8mm wall thickness PLA mold. Until now I have super glued a thin disk onto the bottom, but a plaster pour again woke me up to how much outward pressure the heavy slurry exerts on molds tasked to contain it - the glue failed! This time I am doing a "belt and suspenders" solution. This bottom disk is much thicker and stronger and it is removable. These paper clamps hold it onto the flange and are recessed so the whole thing can sit flat-side down on the table.

Cutting-edge ceramic 3D printing is happening in dental! The focus is not primarily on the printers, attention is going into the paste. They are calling it "the resin" because acrylic resin is the likely medium. Pure alumina powder is being used (also pure silica). Imagine having a pure alumina tooth! What temperature does it take to fire these (and burn out the photopolymer network)? 1600C! They are achieving high percentages (likely 70%+) of the powder in an acrylic resin base and yet the slurry is very fluid (so it can be printed in a very narrow extrusion) and has minimal fired shrinkage. They are adding uV hardeners, this enables solidifying the material as soon as it leaves the printer nozzle. Data sheets specify exactly what uV wave length is needed. The key to the success of these efforts is meticulous lab work to perfect and adapt already established processes and materials. This material-centric lead could be adapted to so many other branches of ceramic fabrication and so many other materials could be made into resins. Another exciting area is investment casting. Thin ceramic shells are being printed and molten metal poured in to get shapes never before possible.

Traditional 50:50 kaolin:silica kiln wash can be a real bummer to use. It flakes, both on drying and after every firing. Pieces of it stick to the feet of ware (plucking). It is not refractory enough either. Shelves need cleaning and rewashing often. Three outside-the-box ideas make this a better recipe.

#1 No raw clay! Strangely, calcined kaolin is better than raw kaolin, it imparts multiple advantages.
#2 No silica. We use zircon or alumina instead, they are more refractory. And we use 80%, not 50%.
#3 We add CMC gum. It is the hardener, it enables a high specific gravity, imparts awesome brushing properties and slows down drying on cordierite and alumina shelves.

The low water requirement and slow drying make this behave more like paint. It can be applied by roller or brush. Coverage is much more even and it does not shrink and crack on drying. Normally the raw kaolin in 50:50 kiln wash suspends the slurry, makes it brushable and hardens it on drying. But CMC gum is way better for the latter two. It is so nice to be able to apply a thin layer of wash even on highly porous shelves (like these alumina ones we make ourselves). Unfortunately, we can't have everything - a down side of this recipe is settling (more information on the recipe page linked below). Fortunately, if used every few days it won't be a problem.

This is not available as a product, we just like it so much we made a label for it!

There is an undeniable appeal to the bright colors of many commercial glazes. While nobody is recommending abandoning them and going all-in on DIY, there is an appeal to having more control. If you are a potter, hobbyist or small manufacturer, consider: Do we want customers eating and drinking from these kinds of glazes? This type of ware is often crazed (runny glazes do that, especially on bodies they were not designed to fit). These are also prime candidates for leaching the high percentages of the heavy metals they contain. All those layers running and pooling on the insides can make pieces into glaze compression time bombs. For food surfaces, the glaze manufacturers want us using their recommended balanced, lightly colored products. Good news! These base recipes are also the easiest to make yourself. When did we get intimidated about mixing our own glazes anyway? No one has to go full mad scientist on DIY here. Research the common ingredients your supplier offers. Use recipes that pass a sanity test. Be a savvy consumer - these colored products are expensive and using them only on the outsides will cut your costs in half. Learn to add pigments to your base recipes and save even more. Then learn to make and use dipping glazes (not dripping glazes) and save time also.

Color like this, from commercial brushing glazes, has become so trendy that multiple problems associated with it are being ignored by potters and hobbyists at cone 6. First, crazing (this network of fine cracks): When people use dense-burning bodies, ware doesn't leak, so it is deemed to be OK. When ware is made using stoneware clays having higher porosities, and it leaks, the clay bodies are blamed. And the poor strength resulting from the crazing is also blamed on the clay. However, this potter has done two right things:
1. Using an iron-stained honey glaze on the inside (e.g. GA6-B). It does not, cannot, leach heavy metals. Many are misinterpreting the ASTM D-4236 label on glaze jars and using intense heavy metal colored glazes on food surfaces!
2. The honey glaze inside does not craze so the mug does not leak even though the body has a higher porosity than the supposed vitrification magic number of <0.5%.
The bottom line: Use glazes that don't craze, DIY ones if possible or necessary, don't use really bright colors on food surfaces.

Dec 6: I have been waiting since Dec 1 for someone to notice this was AI-generated! That happened today. I used an AI image for an obvious reason: A real piece would offend the maker. AI produced this on first try as representative of what's on social. Yes, AI photos are less authentic than DIY, so are pieces made in isolation of awareness of the critical design and safety flaws outlined here. This page gives part of the solution and links to full solutions.

Typical zero-boron high-temperature glazes will not soften in a 1500F decal firing. But low-temperature glazes will (especially those high in boron). Even middle-temperature ones, especially those having significant B2O3, can soften. G3806C (right), for example, is reactive and fluid, it certainly will. Even G2926B, which has high Al2O3 and SiO2, has tiny pits (because of the amount of B2O3 in contains). In serious cases, they can bubble like the mug on the right. What happened to this one? Steam. It was in use and had been absorbing water in the months since it was first glaze-fired at cone 03. The one on the left was not used, but it did have some time to absorb water from the air, it is showing tiny pits in the surface. Even if moisture is not present, on refire low fire bodies continue to generate gases of decomposition that affect glazes. Each decal manufacturer has a recommended firing temperature, that is for their decals, not your glaze.

This is a buff stoneware body, Plainsman M340. A L3954F black engobe was applied inside and upper outside at leather hard. The piece was fired at cone 6 using the PLC6DS schedule. The inside, totally clouded glaze is G2926B. Outside is GA6-B Alberta Slip amber transparent. Normally this inside glaze is crystal-clear on other bodies (and on this one without the black engobe). Clearly, the black stain in the engobe is generating tiny gas bubbles at the exact wrong time during the firing and the melt is unable to pass them. The outside glaze on on the same engobe, but the GA6-B glaze is demonstrating its ability to clear the micro-bubble clouding. It contains a lot of Alberta Slip, a material that is not finely ground like others. Particles across the range from 60-200 mesh are present, some of them appear to be acting as a fining agent to clear the bubbles.

While these are available as commercial products you may want to mix your own to get maximum flexibility in surface character and color intensity. The key is phosphorescent pigments added to a transparent base recipe. The pigments are often made from strontium aluminate doped with rare earth elements like europium and dysprosium. This eBay search reveals they are readily available (using the search 'strontium aluminate glow powder'). While expensive, they are much less so than materials like cobalt oxide or lithium carbonate. These pigments are known for their long-lasting glow compared to older zinc sulfide-based products. It would be best to start at low temperatures, cone 04-06. Consider trying the G1916Q glaze base recipe first (then G3879, if you can get the frit). The Q recipe is temperature, thermal expansion and gloss adjustable (using different frits and frit mixtures). A common starting point is 10-20% pigment by weight.

This is a cone 6 porcelain mug with G2934 matte glaze (with 6% black stain added). We get this satin matte effect in our test kilns using the PLC6DS schedule. Larger kilns cool slower so this glaze turns out too matte in them, we deal with that by increasing the percentage of glossy base (this is a 15:85 blend of G2926B glossy and G2934 matte). The gold decal is from Sanbao Studio. On the left, it has just been applied, other than the glossy finish revealing its location, no gold design is visible. But, after the decal firing, using the MDDCL schedule, we get the result on the right.

The G2934 base matte recipe is good for decals because it has a very low B2O3 content (unlike high boron glazes that can begin to melt very early, even in a decal firing, and alter their degree of matteness or even produce tiny pinholes or blisters). G2934 can tolerate some high-boron G2926B glossy, enough to de-matte it, and still work well with decals.

This is G1947U clear glaze with 8% Mason 6021 encapsulated red stain added. The body is P700, a Grolleg kaolin porcelain. The one on the right, having significantly reduced clouding within, has one tiny addition: 2% Zircopax. It is acting as a micro-bubble fining agent, producing a brighter color and smoother surface. But there is a possible problem: These stains are not recommended for use above 2300F. Even though the color is very good, cone 10 is just on the edge of the limit temperature, so suitability for food surfaces would require careful testing for leaching cadmium.