Loulou Posted January 28, 2012 Report Share Posted January 28, 2012 I am looking for a porcelain slip casting recipe that when fired is very durable, even when thin. This could be a mid range or high fire recipe. Link to comment Share on other sites More sharing options...
Mark C. Posted January 28, 2012 Report Share Posted January 28, 2012 I think I have two in an my old clay mixing book-Its been 35 years since I have used these-not sure on thin strength .These are all cone 8-10 All old school stuff here Mark casting porcelian spar 25 epk 40 flint 25 ball clay 10 +sodium silicate 1/4 of 1% or 1/2 tsp strain 6-8 times-60-80 mesh screen Pats casting porc slip EPK 2.5 lbs ball clay 2.5 lbs silica 2.5lbs spar 2.5 lbs HSU casting porc slip 3 gal. EPK 25 3405 Ball clay #4 25 3405 Feldspar 25 3405 Silica 25 3405 Sodium Silicate 34 Soda Ash 34 12 lbs. Add deflocculants to water 1st 4 lbs H20 for 10 lbs. clay when I had a slip casting business for 12 years we used darvon instead of sodium silicate to deflocculate it works better-we cast 40,000+ candle lamps and gave up on soda ash as it hard on the plaster molds over time Link to comment Share on other sites More sharing options...
neilestrick Posted January 28, 2012 Report Share Posted January 28, 2012 Looks good to me. If you're doing a small batch, skip the screening and mix it with a stick blender. Link to comment Share on other sites More sharing options...
mishelart68 Posted June 21, 2020 Report Share Posted June 21, 2020 Hello ... I recently mixed a fresh batch of porcelain slip and mixed in some older slip that I'd had a some months. It mixed smoothly, but now, after a few days, the water is on top and all thr solids are on thr bottom of the bucket. When I try to use my drill mixer, it's clumpy and hard to do. How do I fix this? I thought about scooping the mix out by hand and sieving it into another bucket. Link to comment Share on other sites More sharing options...
liambesaw Posted June 21, 2020 Report Share Posted June 21, 2020 7 minutes ago, mishelart68 said: Hello ... I recently mixed a fresh batch of porcelain slip and mixed in some older slip that I'd had a some months. It mixed smoothly, but now, after a few days, the water is on top and all thr solids are on thr bottom of the bucket. When I try to use my drill mixer, it's clumpy and hard to do. How do I fix this? I thought about scooping the mix out by hand and sieving it into another bucket. What are you using as a deflocculant? I had issues with hardpanning when I used sodium Silicate, but when I changed to darvan 7, no issues. I use a large drill with a big ole blunger on it, it has a "hands free" trigger setting and if it's been a while I just hook the cord under the bucket and let it mix itself for 10-15 minutes. After that it's usually smooth as silk Link to comment Share on other sites More sharing options...
mishelart68 Posted June 21, 2020 Report Share Posted June 21, 2020 Okay ... that must be it. I used sodium silicate in my mix. How do I correct the problem since I've already used sodium silicate? Link to comment Share on other sites More sharing options...
liambesaw Posted June 21, 2020 Report Share Posted June 21, 2020 2 hours ago, mishelart68 said: Okay ... that must be it. I used sodium silicate in my mix. How do I correct the problem since I've already used sodium silicate? I believe you need to mix it every few days to keep it from doing that. Link to comment Share on other sites More sharing options...
neilestrick Posted June 21, 2020 Report Share Posted June 21, 2020 I'd say it's the amount of sodium silicate, not necessarily the sodium silicate itself that's the problem. I've mixed batches of casting slip with SS and never had problems. If it's separating out, then it's probably been overly-deflocculated, or has too much water. You could try adding dry material. Link to comment Share on other sites More sharing options...
mishelart68 Posted June 21, 2020 Report Share Posted June 21, 2020 liambesaw, neilestrick ... thank you guys! I will try these steps. Link to comment Share on other sites More sharing options...
liambesaw Posted June 21, 2020 Report Share Posted June 21, 2020 Doesn't help that sodium Silicate comes in different strengths, and they never give the strength on the bottle or the recipe. Link to comment Share on other sites More sharing options...
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