momspindy Posted November 13, 2020 Report Share Posted November 13, 2020 Had slip in pouring table to long and slip hardened. It is low fire slip. We added water and add casting slip thinner. The slip seems thin enough but parts of greenware are collapsing while drying in mold. It was not emptied to quickly. It has desired thickness, but a portion of the greenwear collapses. It stays soft. It also seems to thicken up and not drain well. Any help is appreciated. Paul Link to comment Share on other sites More sharing options...
Min Posted November 13, 2020 Report Share Posted November 13, 2020 22 minutes ago, momspindy said: We added water and add casting slip thinner What is the specific gravity now compared to when the slip is freshly made? Water evaporates, deflocculants don't so my guess would be it's over deflocculated. I've never mixed an entire batch from scrap which in effect your tank of dried slip is, don't know if this is part of the problem too? @Mark C. has done a lot of slipcasting in the past, he might know the answer. Link to comment Share on other sites More sharing options...
Mark C. Posted November 14, 2020 Report Share Posted November 14, 2020 (We added water and add casting slip thinner) I assume casting slip thinner is Darvon 7? Min said (Water evaporates, deflocculants don't so my guess would be it's over deflocculated) That is right so all you needed was water so what you need now is more dry slip Really you need a slip hydrometer(they are short and fat) and a ford cup to measure the flow rate-without these tools and the specific gravity # of fresh slip made right you are operating in the dark Its been a long time since I was doing slip but those tools make all the difference .Like driving nails without a hammer Link to comment Share on other sites More sharing options...
momspindy Posted November 14, 2020 Author Report Share Posted November 14, 2020 The specific gravity is 1.96 I added water to get it to 1.75. will see what that does first. How do I counteract the darvon 7 if we added to much? Thanks Link to comment Share on other sites More sharing options...
Bill Kielb Posted November 14, 2020 Report Share Posted November 14, 2020 7 minutes ago, momspindy said: The specific gravity is 1. I add water to get it to 1.75. Just checking here, if the specific gravity is one then that would be pure water with nothing in it. Adding water to a mixture of water and slip usually decreases the SPG because the sample is being diluted. Just checking to make sure you have the measurement thing correct before you start to make adjustments. Link to comment Share on other sites More sharing options...
Mark C. Posted November 14, 2020 Report Share Posted November 14, 2020 42 minutes ago, momspindy said: The specific gravity is 1. I add water to get it to 1.75. will see what that does first. How to I counteract the darvon 7 if we added to much? Thanks Add more dry slip to counteract to much Darvon 7. Do not add any more water. Get the ford flow cup and learn how to use that for flow rates. Get the slip hydrometer and use that as well. You need them both Link to comment Share on other sites More sharing options...
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