These pieces were slipcast from Plainsman M370C and fired to cone 6 using the PLC6DS firing schedule. The dipping glaze is G2934Y, a recipe variant of G2934 having a finer micro-surface texture (it has the same chemistry but the MgO is sourced from a frit and talc instead of dolomite). The degree of matteness can be tuned by recipe or firing change, or both. As an MgO matte it is very pleasant to the touch. It fires durable, can be quite matte without cutlery marking and it has very good slurry and application properties (as a dipping glaze). It has a very low thermal expansion (won’t craze on anything). It works really well with stains (except purples). It melts better than our G2926B glossy, even though it fires matte!

These porcelain mugs are sold at many tourist shops on the Alaskan cruize circuit. Made in China of course. But their quality is astounding. And they teach multiple lessons to potters - great skill in the use of decals (even inside), meeting different glazes at the rims, evenness of application, layering, the use of wax resist, etc. They likely have a glossy and matte base glaze and add stains (to get the black, blue, red, white, green). Notice they have an iron red (lower right) that is stable enough not to run and host an even more fluid melt second layer. They also have a stoney yet functional matte white (bottom left). You can make dipping glaze versions of all of these:
Black glossy: G3914A and G2926BL
Black matte: G2934BL
Iron Red: G3948A
White stoney matte: G2934Y2
Glossy colors: Add stains to G2926B
Matte colors: Add stains to G2934

This is revolutionary because it is now practical to make one-off jigger test molds in one step using a consumer 3D printer and no plaster original model. Draw, print, glue, pour plaster, peel off (or heat off using a hair drier) the printed PLA piece by piece and you are ready to jigger test mugs.

3D design of this is simple: Sketch the outside profile of the mug and the mold, join them at the rim of the mug and then rotate. While the whole thing can be printed as one piece, print-time is drastically reduced by doing them as separate pieces and gluing. It is also best to print the step section of the mold much thicker to guarantee roundness for fit into the cuphead or ring. Printing the base of the mug separately is most advantageous, that eliminates the need for generating support and enables doing multiple iterations of embossed designs or logos. Printing a small inside ring to hold it in place for glueing is a also good idea.

This was printed as an assembly. The grooves between the teeth were filled with support but it cleaned out easily. The hinge moves smoothly and has no slack. I did not draw it, I downloaded it as an upgrade to the door in my Creality K1 Max printer. Making something like this is a good lesson in the precision that consumer printers are capable of. Stratasys, a long-time maker of industrial 3D printers is suing Bambu Labs, a maker of low-cost consumer machines similar to those from Creality. Stratasys apparently sees a real threat from consumer printers that are gaining quickly, and in some ways surpassing the capabilities of industrial devices.

Black-burning bodies are popular with many potters. This one is stained by adding 10% raw umber to a buff-burning stoneware. Umbers are powerful natural clay colorants, they have high iron and also contain some manganese oxide. Could a white engobe produce a porcelain-like surface on such a clay body? Yes. L3954B engobe was applied during leather-hard stage to this Plainsman Coffee Clay mug (on the inside and partway down the outside). After bisque, transparent G2926B glaze was applied inside and GA6-B outside. Notice the GA6-B over the engobe fires amber but over the black it produces a deep glossy brown. The engobe was mixed into a thixotropic slurry, as explained on the page at PlainsmanClays.com (see link below), and applied in a relatively thin layer. This porcelain-like result is a testament to the covering power of a true engobe. It is no wonder they are so popular in the ceramic tile industry - a red burning body can be turned white as a porcelain, that enables all the marvellous glazing and decorating they can do.

Yes. If it is a true engobe. This is L3954B fired at cone 6 on Plainsman M340S, it is fire-shrinkage-fitted to this clay body and opacified with Zircopax. The cover glaze is G2926B transparent. The opacity that this engobe is able to achieve here is because it is vitrifying to the same degree as the body, no melting is occurring and that is why it is completely opaque (even though it is applied as a very thin layer at the leather hard stage). This same performance could be expected in reduction firings to block the iron speckle (using the L3954N and variations recipes).

This is a cone 10 glossy glaze. It has the chemistry that suggests it should be crystal clear and smooth. But there are multiple issues with the materials supplying that chemistry: Strontium carbonate, talc and calcium carbonate. Each has a significant LOI and produces gases decomposition. When the gases need to come out at the wrong time it turns the glaze into a Swiss cheeze of micro-bubbles. A study to isolate which of these three materials is the problem might make it possible to adjust the firing to accommodate it. But probably not. The most obvious solution is to just use non-gassing sources MgO, SrO, CaO and BaO (which will require some calculation). There is a good reason to do this: The glaze contains some boron frit, that is likely kick-starting melting much earlier than a standard raw-material-only cone 10 glaze. That fluid melt may not only be trapping gases from the body but creating a perfect environment to trap all the bubbles coming out of those carbonates and talc. All of this being said, a drop and hold firing schedule could also smooth it out a lot.

This was done in Fusion 360.
1: A make a sketch of a box, around the handle, on the XY plane. Offset that outward by 1.2mm (my printer prints 0.4mm wide, three passes give good strength).
2: Extrude to create box 1: The base backward by 1mm and the sides forward by 20mm.
3: Use five sides of the box as cutting planes to slice it out of the mug.

At this point I could print this in PLA filament, pour plaster into and then use a hair drier to peel it off. But let’s make rubber molds instead.

4: Move the box-with-handle away from the mug. Pull the four sides out by 5mm to thicken them.
5 & 6: Create box 2 around the outside of it, as a new body, 1.2mm wider and taller, 1mm more frontward and 1mm less backward.
7: Use box 1 as a cutter to remove material from box 2 and then pull the outer 1.2mm sides 5mm backward.
8: Shell out the back side to 1.2 wall thickness and make two 9.4mm holes (to accommodate natch clips).

To make side 2 mirror-image a new body using the front or back as the reflexion plane. The back side is then filled with PMC-746 rubber to make the block mold. Plaster is poured into that to make each working mold.

The crawling is happening at sharp concave surface contours (e.g. inside bottom corners on mugs) and on pieces like this. G2934 has good melt fluidity so that is not the issue. Here are some questions to consider:
-Did the glaze crack on drying? That is a sure sign it will crawl. Did you use calcined kaolin as specified in the recipe? That helps reduce the shrinkage as it dries (to eliminate the cracking).
-This looks like it is going on pretty thick - was it correctly mixed as a thixotropic slurry (high water content, 1.44 specific gravity, and gelled)? Or was it mixed with low water content (e.g. 1.55 specific gravity).
-These crawled areas were disturbed during spout forming, what can be done to repair the surface then?
-This is firing pretty glossy so kiln cooling is likely pretty fast. A drop and hold firing can help (as long as the glaze is not too thickly applied).
-Slower cooling means it will likely fire too matte, that is why we make an 80:20 blend of G2934 and G2926B glossy - to enable tuning matteness to any firing schedule.
-Mix up some of it as a brushing glaze. Apply a thin layer onto the bisque in the areas likely to crawl. Then dip the whole piece in the dipping glaze version.
-Mix the batch as a base coat dipping glaze, then it will adhere better to the bisque.
-Reduce the amount of calcined kaolin somewhat in favor of raw kaolin (perhaps 5%) - that may produce a slurry with better coverage and adherence.

The machine is being cleaned in preparation for a porcelain run (after producing stoneware clays). The pugmill has been stripped down completely - all parts in the main chamber, vacuum chamber and in the nose). The casings, augers and other components are washed, dried and inspected. Clean-downs and associated maintenance like this are costly but necessary to ensure quality porcelain. Each time we do this we are reminded how amazing this machine is - it can premix, pug and de-air even the most difficult of all clay bodies, Polar Ice. That body can be thrown straight out of the machine as plastic as it would be if aged for a year. This machine routinely produces 600+ boxes per day, turning powder into pugged in a continuous operation.