Celia UK Posted August 16, 2016 Report Share Posted August 16, 2016 I have just poured the inside of a stoneware cylinder (test piece bisqued to 1000oC) with a transparent glaze that crawled horribly in a previous batch. This is a commercially mixed dipping glaze - very reliable by all accounts! Following advice here and elsewhere I let it stand and drew the excess water off the top. The glaze is now like pouring cream consistency. 100ml weighs 153g. I've poured the inside - about 3 seconds. As it dried the glaze cracked - see photo. What does this indicate? Can I just finger-sand it and dip the outside or am I destined for more disappointment? Link to comment Share on other sites More sharing options...
Joseph Fireborn Posted August 16, 2016 Report Share Posted August 16, 2016 If the glaze cracked, it is going to crawl 95% of the time when you fire it. Unless it is really fluid. So it's probably best to scrap it and wash it and dry it. To me it sounds like your glaze is too thick and creamy, even if its weight/ml is close to what you want, it sounds like you need to add Darvans in small amounts and stir until you can poor a cup and it not crack. A few drops goes a long way. Link to comment Share on other sites More sharing options...
Celia UK Posted August 16, 2016 Author Report Share Posted August 16, 2016 Thanks Joseph. Do you know the UK equivalent of Darvans? Link to comment Share on other sites More sharing options...
Joseph Fireborn Posted August 16, 2016 Report Share Posted August 16, 2016 No idea. I am sure others will weigh in that might have a better idea of what to do. I know I had a glaze with this issue, if I added water the color was to thin, but it was way to thick to dip/pour or spray. It had a lot of Gerstly Borate in it which made it absorb water like crazy. So I used Darvans to thin the glaze without adding more water. It worked brilliantly. You could try searching for deflocculant and see what comes up on the forums or google. Link to comment Share on other sites More sharing options...
Magnolia Mud Research Posted August 16, 2016 Report Share Posted August 16, 2016 Celia DARVAN 7 - Sheffield-Pottery.com www.sheffield-pottery.com/DARVAN-7-p/rmdar7.htm "Darvan No. 7 is a high molecular weight, ... DARVAN® 7-N October 25, 2005 RTV Product Code: 14395 Composition: Sodium polymethacrylate aqueous solution LT Link to comment Share on other sites More sharing options...
Marcia Selsor Posted August 16, 2016 Report Share Posted August 16, 2016 Was you pot moist? I always dampen my pots before glazing so they don't suck in the glaze. Marcia Link to comment Share on other sites More sharing options...
Mark C. Posted August 16, 2016 Report Share Posted August 16, 2016 Wash the glaze off and let pot dry and start over. Link to comment Share on other sites More sharing options...
Chilly Posted August 16, 2016 Report Share Posted August 16, 2016 I use Sodium Dispex, which is, I think, a replacement for Darvan. It makes the glaze very liquid for adding the tiniest drop. Link to comment Share on other sites More sharing options...
Babs Posted August 17, 2016 Report Share Posted August 17, 2016 Pouring cream consistency for a C06 bisque. May be way too thick. I'd test a few tiles with measured added water quantities. Then wipe out pot with damp sponge. You don't have to test fire your tiles, go with the "thickness which doesn't crack on the tile dip test..or have you been there and such application is too"skinny" for the look you want? Link to comment Share on other sites More sharing options...
Babs Posted August 17, 2016 Report Share Posted August 17, 2016 Get rid of the cracked glaze on pot first😊 Link to comment Share on other sites More sharing options...
Celia UK Posted August 17, 2016 Author Report Share Posted August 17, 2016 How I love this forum - wake up to find all this advice, it's great! I washed off the old glaze last night. The pot is drying off in the airing cupboard. I added a small quantity of sodium silicate to my bucket of glaze. First time round I did wipe the pot before pouring the inside - and NOW .... I'll try dipping a test tile as you suggest Babs and will dampen the pot by wiping again before a second pouring attempt. That means I've followed the advice of everyone above. Watch this space! Link to comment Share on other sites More sharing options...
Celia UK Posted August 17, 2016 Author Report Share Posted August 17, 2016 Yay! Not a crack in sight! Thank you all😀😀😀 Link to comment Share on other sites More sharing options...
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