Monthly Tech-Tip from Tony HansenI will send practical posts like these (from thousands I maintain). No ads or tracking. We are troubleshooting the confirm email, for now you will be subscribed immediately (the first monthly email will provide one-click unsubscribe). BlogLead bisilicate with his ugly borosilicate cousins at a cone 05 partyThe middle front mug is glazed with an 85:15 lead bisilicate:kaolin mix, the G3971 recipe. It is an absolutely "knock your socks off" crystal-clear hyper-glossy surface that transmits the terra cotta color beautifully regardless of whether the clay is smooth or coarse or the glaze thick or thin (this one was applied as a brushing glaze in three coats on L215). My lead testing kit passes it with no detectable lead release. The other pieces are done using brush-on versions of boron-based clear glazes (commercial and made from a recipe). At almost any thickness and whether on L215 or L4170B clouding occurs. The worst one is a commercial three-coater on the right, the best is G1916W (it has 2% added iron as a fining agent for the micro-bubbles). My terra cotta plan: Glaze the inside functional surfaces with that and the outsides with the leaded one (and using a kiln exhaust system). Context: Lead Bisilicate Frit, A lead bisilicate frit.., 2 iron oxide in.., Boron blue in low.., A cure for long-time.., Is it impossible to.., Thick application clouds a.., Lead in Ceramic Glazes.. Sunday 17th March 2024 Use the same runny glaze as its own catch glazeThis is G3948A, a super runny cone 6 iron red glaze. The clay body is M340. This glaze has to be runny, applied thickly enough, be held at temperature and cooled slowly to achieve this visual effect. When applied at the needed thickness it will run off the ware onto the kiln shelf during firing. Why has that not happened? A catcher glaze on the lower section. In this case, the catcher is the same glaze. On the left, the bottom half of the mug has just been dipped into the glaze quickly, giving a layer that is too thin to achieve the red effect. That dried within a few seconds and enabled pushing the top half down into the dipping glaze for twice as long (the inside has a liner glaze and is waxed up to the rim). The upper section glaze is guaranteed to run and the bottom is not thick enough to run. The result is complete blurring of the dividing line and coverage that looks natural and flawless. Context: Stop a runny glaze.., Catch Glaze Tuesday 5th March 2024 ChatGPT woke me up about making my own frits.I asked ChatGPT this question and got a very thoughtful answer that seems to confirm what I have observed in smelting material mixtures into ingots in alumina and zircon lined slip cast crucibles. The mixtures are melting well in the test crucibles (the upper one was fired at cone 4, the lower one at cone 6). But there are issues. There does appear to be phase separations. And bubble froth at the top. For some compositions alumina works better as a liner, for others zircon. We are getting closer to trying larger multi-kilogram batches and ball milling so time will tell. Context: Crucible with alumina oxide.., AI in Ceramics Friday 1st March 2024 Paint another layer onto a fired glaze? Yes. With CMC gum.The cone 6 mug on the left has the G3933A glaze, applied as a dipping glaze. It turned out poorly - crawling from corners and looking thin and washed out. I made a brushing glaze version of this (which adds 1.5% CMC gum), I keep it around for this very purpose. It has a high specific gravity (unlike commercial ones that have high water contents - they will run and go on too thin if you try this). Because of the gum it dries hard, there is no shrinkage or cracking. On a second firing, using the C6DHSC schedule again, (mug on the right) the surface is transformed - thicker, more vibrant color (being picked up from the underlying body). Context: CMC Gum, Six layers 85 Alberta.., Control gel using Veegum.., Convert a pint of.. Wednesday 28th February 2024 Iron red glaze fired at cones 6, 5 and 4These mugs are Plainsman Coffee Clay. The glaze on all three is G3948A iron red. They were fired at cone 6, 5 and 4 using the C6DHSC schedule (adjusted for top temperature). As can be seen, the red color depends on the melt fluidity achieved at cone 6. Context: Same glaze on black.., Iron Red Glaze Sunday 25th February 2024 Finished cast v1 stoneware beer bottlesThe center bottle is a standard glass one, the other two are ceramic, cast out of the version 1 plaster mold. The stopper fits perfectly. The clay is Plainsman M370 + 10% raw umber, it fires black. The glaze is GA6-B. They were fired using the C6DHSC firing schedule. The slightly larger size will enable inserts at the bases to inlay a logo or other info. These bottles are a testament to how 3D printing and 3D design now make it possible for even casual potters to make pieces never before practical or even possible. Context: Slip cast leather-hard full-sized.., Beer Bottle Master Mold.. Saturday 24th February 2024 Version 2 ceramic beer bottle block moldThis time I printed the block mold, rather than the case mold, in six pieces on my consumer 3D printer. Context: Slip cast leather-hard full-sized.., Beer Bottle Master Mold.. Saturday 24th February 2024 This impossible AI porcelain mug suggests it is actually learningConsider these porcelain mugs I "imagined" at MidJourney.com. At first, they look pretty typical but take a closer look at the one in the middle. The floral design on the one behind morphs into the actual 3D shape on the one in front. This seems like an indication that the AI is actually drawing these, not just plagiarizing them from its scraping activities online. The #aiart, #aiartwork, #aiartcommunity and similar hashtags generate millions of posts (albeit of questionable taste), but they are a harbinger of things to come. Context: These pots are not.., AI in Ceramics Saturday 24th February 2024 These pots are not real. How is that possible?I created these images using the "imagine" command at MidJourney.com. To me this is jaw-dropping - I thought AI was just plagiarizing but it really does appear to be learning. Top left: I asked for "stoneware pottery mugs with floral decoration covered by a glossy transparent glaze". For the vase: "Crazed transparent glaze over floral decoration". How does it know what crazing is? Notice the things I forgot to specify for the porcelain mugs: Handmade, one handle, decoration should only be on the outside and handles are not decorated (these errors seem like an indication that this AI has not learned that yet). For the last one, I asked for a piece demonstrating the difference in runniness of two different glazes. How does it know what runny glazes are? How does it know a bowl would be the best shape to demonstrate the latter? These observations and the fact that it can generate very high-resolution images seems to indicate it is actually drawing the pieces, not just showing photos it found online. Context: This impossible AI porcelain.., AI in Ceramics Saturday 24th February 2024 Drying cracks in bricks - why is this happening?These bricks are being extruded in India and the plant is suffering drying cracks. A consultant recommended the addition of lignosulphonate (at a cost of $800/ton) as a solution. But before adding such a large expense, some obvious changes seemed in order first. The technician knew the plasticity index of the clay (a measurement used for soils) but he did not have records of its drying shrinkage, water permeability, drying strength or drying performance. When problems like this arise the value of such becomes evident - that knowledge provides direction when things like this happen. It would answer some questions. Is cracking happening because of lack of drying strength or plasticity or because drying shrinkage is too high. The splitting along the corner of the extrusion is a clue that plasticity could be lacking - that could be solved by a small bentonite addition or reduction in grog. If permeability is low an increase in grog might be needed (if the pugmill can extrude slugs with a smooth edge and corner). Notice the cracks that start from those splits (lower left). But also notice how the top edge has shrunk while the center section has not. That indicates a drying process that is not engineered to subject all surfaces to equal airflow (sure enough, these are being dried outside in the sun and wind). Another factor is cross-section: The round holes create variations in thickness that exceed 300%, square holes with round corners would be better. Given the location and economic realities, the change to square holes might be enough to ignore all the other issues and get away with it. Context: Bricks and tiles are.., Clay lab report Is.., Physical Testing, Cracking of Clays During.. Friday 23rd February 2024 | Contact MeUse the contact form at the bottom on almost all the pages on this site or let's have a together. Other ways to Support My WorkSubscribe to Insight-Live.com. It is about doing testing and development, not letting the information slip away. Starts at $15 for 6 months.
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