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In Store Shopping availablePlainsman Pottery Supply is open for in-store shopping. Pickup orders may still be placed via email at larry@plainsmanclays.com, or over the phone by calling 780-440-4791. Click the links to the left to get information and pricing on our products. Click the "Plainsman Data Sheets" for details information on the use and Plainsman clay bodies and glazes. The blog below is intended to help you with all manner of technical issues in ceramic hobby production, these posts come every few days, so check back often. Technical Tips Blog3D printed mold tests of embossed logoWe want to achieve embossed lettering inside the foot rings of slip-cast ceramic pieces by using a standard consumer 3D printer with PLA filament. There are plenty of obstacles to overcome in doing this. Since plaster does not release well at all from lettering having sharp corners, bevelling has to be done. However, our CAD software has problems rounding the corners of many fonts, I had to search for one having no variations in stroke width. Then it was a matter of discovering how much to extrude and how much bevelling it would tolerate - this one permits a 1 mm extrusion with a 0.6 radius bevel. Context: 2 19 Jiggering-Casting Project.. Thursday 31st October 2024 Milk-as-a-glaze goes on more evenly by spongeThe milk was applied to inside-glazed L210 terracotta ware (fired to cone 06) that I had preheated to 250F. This has not gone on as thick as usual so it appears it might be best to dip the pieces into milk and then pat them with a milk-damp sponge to break all the bubbles, remove the drips and even out the coverage. Context: This crack is spring.., Milk as a glaze.., Using milk as a.. Wednesday 30th October 2024 3D printed three-piece jigger case mold completeIt is now practical to make true-round, perfect-fitting, all-in-one case molds for jiggering using a consumer 3D printer and PLA filament. This is a one-off test mold using a consumer printer, but the method is so fast that production molds on an industrial printer are feasible. The process is: Create the drawing in 3D CAD (e.g. Fusion 360), print the three sections, glue them, turn the assembled shell upside down, fill with plaster, let it set and peel out the inside two pieces using a heat gun. Context: 3D render for a.., Fusion 36 drawing of.., 3D-Printing, All-in-one case mold, 2 19 Jiggering-Casting Project.. Monday 28th October 2024 Sanity checking a cone 6 purple pottery glazeA customer was having serious trouble with this cone 6 glaze recipe shivering. A quick check of its chemistry reveals the reason: It has the lowest calculated thermal expansion we have ever seen! The reason is the high spodumene and talc levels. Adding the 3% cobalt also makes this among the most expensive we have seen. To say this recipe looks non-typical is an understatement. And, it raises flags on working properties and susceptibility to leaching in both limit recipes (e.g. very low clay content, high talc and spodumene) and limit formulas (stratospheric levels of Li2O and MgO coupled with plenty of cobalt). Context: Limit Recipe, GLC Monday 21st October 2024 Here is why you don't want an engobe to fire too vitreousToo much frit in an engobe and it will lose opacity and whiteness. The white slip on the left is an adjustment to the popular "Fish Sauce" slip recipe (L3685A: 8% Frit 3110 replaces 8% Pyrax to make it harder and fire-bond to the body better). The one on the right, L3685C, has 15% frit. Although applied at the same thickness, it is becoming translucent, moving it into glaze territory. That means it will have a far higher firing shrinkage than the body (a common cause of shivering at lips and contour changes). This slip is basically a very plastic white body. Since white burning slips are made from refractory materials they are not nearly as vitreous as red ones, at low fire they need help to mature and a frit is the natural answer. With the right amount of frit the fired shrinkage of body and slip can be matched and the slip will be opaque. This underscores the need to tune the maturity of an engobe to the body and temperature. Although zircon could be added to the one on the right to opacify and whiten it, that would not fix the mismatch in fired shrinkage between it and the body. And it would increase the price. Context: L3685U, Creating a Non-Glaze Ceramic.., Bi-Clay strips test compatibility.., Potters can learn from.., Applying an engobe by.., Here is motivation to.., Engobe, Opacity Saturday 19th October 2024 A method to make a two-part slip casting mold in one pourThis is part of a project to create a new mold. I have to make various iterations to arrive at a final design where rubber will be used to make the case mold. But until then I will 3D print the case mold directly. Here are some features that make this super cool: Context: How to 3D-design a.., 2 19 Jiggering-Casting Project.., All-in-one case mold, Medalta Ball Pitcher Slip.. Saturday 19th October 2024 Here is what happens when a glaze has too much raw clayThis is an example of how a glaze that contains too much plastic clay has been applied too thick. It shrinks and cracks during drying and is guaranteed to crawl. This is raw Alberta Slip. To solve this problem you need to tune a mix of raw and roasted clay. Enough raw clay is needed to suspend the slurry and dry it to a hard surface, but enough calcine is needed to keep the shrinkage low enough that this cracking does not happen. Perhaps you have been using a glaze having a high percentage of clay and this does not happen - the reason is likely that the clay is not highly plastic. Context: Alberta Slip, Alberta Slip 19 F.., G2934 cone 6 matte.., Crawling, Glaze Shrinkage, Glaze thickness, Subsitute Gerstley Borate in.., Powdering Cracking and Settling.. Monday 14th October 2024 Is Ferro Frit 3124 a viable substitute for Frit 3134?This is a GLFL test comparing the melt flow of the three materials at 1800F. Frit 3124 is barely out of the starting gate and the other two have crossed the finish line! With frits chemistry is a big deal, they are all about supplying oxides to the melt. Frit 3134 is low-alumina/high-boron, 3124 is medium-alumina/low-boron and 3195 is medium-alumina/high-boron. Boron is the melter. Alumina thickens the melt and hardens the glass. Just from this it appears that Frit 3195 is a better starting point for calculations to replace frit 3134. Context: Substitute Ferro Frit 3134.., Material Substitution, Substitute Ferro Frit 3134.. Monday 14th October 2024 Extreme handle fitting: A Medalta v.5 ball pitcherThis handle mold is for v.5 of our 3D mold-making (and discovery) project for the ball pitcher. The process to make the 3D drawing is quite simple: Cut it out of the model (top left), draw and extrude side walls (top right) and slice off and remove the pointy parts (a step-by-step video coming soon). Bottom left: A ready-to-use mold. Notice how it fits perfectly onto the side of the pitcher form (bottom right). Because of the good fit, attaching these is just a matter of using some casting slip as the glue. Casting this handle separately affords multiple benefits: It simplifies making the mold of the pitcher itself, of extracting pieces after casting and it produces a more professional-looking product (without holes inside where the handles join). And, handles can be stockpiled in a damp box, ready to use when needed. Context: Printing an entire one-off.., Pour spout for complex.., Medalta Ball Pitcher Slip.. Friday 4th October 2024 Serious cracking in a crystalline-glazed P700 Grolleg porcelain. Why?The cracks appear to have happened on heat-up (because they have widened). Bisque firing was done around cone 04. Issue 1: The cone 10 electric firing was up-ramped at 400F/hr to 2330F (so it whizzed pass quartz inversion on the way!). Issue 2: Wall thickness variations in the pieces, they produce temperature gradients that widen as firing proceeds. Issue 3: Abrupt contour changes and sharp corners, especially when coincident with thickness variations, provide failure points that rapid temperature changes exploit. Issue 4: This new body is more plastic than the previous Grolleg porcelain used, that was likely an enabler to making these thin wall sections even thinner. But remember, practically any piece (unless it has huge in-stresses from uneven drying) can exit a kiln crack-free if firing is done evenly and slowly enough. Results of past firings are the main guide to know what to do in future ones, this is now a "past firing". So the first obvious fix here is slower heat-up, especially around quartz inversion (1000-1100F). Second: more even wall thickness. Context: How much feldspar should.., Crystalline glazes, Dunting and Cracking of.. Wednesday 2nd October 2024 SignUp For Monthly Tech-Tip EmailPlease visit https://digitalfire.com and use the Register feature at the top of the page. 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Plainsman Pottery Supply, 9517 - 41 Ave NW, EDMONTON, AB T6E 5X7
Phone: 780-440-4791, FAX: 780-490-7591, Email: larry@plainsmanclays.com