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Hi all, Second time posting here and I’m hoping you can help! Hopefully this is the right place to be for a troubleshooting question like this. Im currently working from a recipe for Val Cushing’s Cone 6 Porcelain Slip. grolleg: 15% tile 6: 15% Epk: 3% om4: 10% flint: 25% neph sy: 30% gerstley borate: 2% —————————— Sodium silicate: .0028% calgon: .0005% When I mixed this before, as now, I subbed the deflocculants with Darvan. I mixed it successfully then, but I’m currently have difficulty. I know that darvan generally subs for sodium silicate at 2-1, so bearing that in mind, that’s where I started. I kept adding darvan in small 5g increments up to 100g in a 10000g recipe. That seems like far too much, but maybe I’m wrong? I feel like I’m on the other side of that deflocculation bell curve some how and missed my mark. Every time I come back to the studio the slip is gelled thick but never settled and never develops a skin. When I’ve added more darvan, the slip temporarily thins, but seems to rebound to being too thick the next day. Can the casting process indicate overdeflocculation? If so, in what ways? What should I be looking out for other than settling and a skin in my bucket? Can anyone offer any advice on this recipe or deflocculants? I’ve been doing some hard research and testing and can’t nail it down. My current gravity is measuring at 1.71, so I’m hesitant to add more water, since according to some other online sources I should be aiming between 1.7 and 1.8. I’m wondering if I should throw caution to the wind and say “this slip just needs more water than most”. Ive mixed this slip before with great success two years ago. I have no clue what I did right then. Dumb luck haha. Any suggestions or advice would be greatly appreciated. Thanks!

I recently read that you can use sodium silicate as a post-firing sealant for raw clay, in the same way that it's used to seal concrete, as "water glass". I use cone 6 porcelain, and I love leaving the bare clay as a design technique, but there's still a good chance that the exposed clay will stain with use - esp coffee and tea. So I am going to try using it to protect against future staining after use, but I wonder if I put it on before the pots go into a luster firing (cone 018), will the sodium silicate molecules bond more completely with the clay body? Will it eventually wear away with use? It doesn't stand to reason that it would burn away, since it's not organic, but will it volatilize? I can't find very much info on this specific use of sodium silicate, either, though I have discovered a mind-blowingly large amount of uses for it in all kinds of industries, as well as just ceramics. Thanks!

Thought I'd share a success story here with my Terra Sigillata recipe. Everything I've ever read says that you need sodium silicate or sodium carbonate but it seems that Tetrasodium EDTA - aka Jet-Dry works as well. 3 parts Clay 1 part water 2 teastpoons Jet-Dry I used a small bottle to mix up a test batch as I wasnt sure that it would work at all. Previous attempts at using Calgon were unsuccessful as I read that the old recipe containing phosphates was changed. So, if you dont have sodium silicate or sodium phosphate handy you can give this a try and see if it works for you. Full post here - https://dreamsofearth.wordpress.com/2015/05/24/terra-sigillata/

My Standard ceramic Seamist glaze was going on too thick, even though the specific gravity was measuring ok. It was not settling out in the bucket at all upon standing. On a dipped piece, the glaze would take forever to dry, and would have cracking issues. In many hours of research (and reading at times what seemed to be contradictory advice) , it sounded as though the addition of sodium silicate should thin down the glaze, which is what I thought I wanted to do. I even watched John Britt's video showing exactly what sodium silicate does to his glaze that was behaving like mine -- his thinned down nicely. Mine, on the other hand, gelled up when I added sodium silicate! How could that happen? It seems counter-intuitive, and yet that's what happened. I'm hoping to salvage this bucket of glaze -- is there any advice that will help me? Thank you!

I have become somewhat interested in the technique of creating texture on thrown pots using sodium silicate. i am curious to know if anyone has ever tried to use other materials to create a similar effect? I know it's easy to order the stuff online (when freezing isn't a concern) and I could make it myself from lye and desiccant. Just wondering if there is any other readily available liquid that offers a similar outcome. (I suppose I am being a bit lazy, too - who really wants to run out to Walmart when the temps are in the single digits, there's 2 feet of snow on the ground and the driveway's coated with ice?) Thanks.