JoannaPardue Posted April 3, 2019 Report Share Posted April 3, 2019 Hi, I am new to making ceramics and I need some help. After taking my clay out of the molds they look good but when they are dry and ready to kiln I notice that they are cracked. I cannot figure out why. Please help. Link to comment Share on other sites More sharing options...
JohnnyK Posted April 4, 2019 Report Share Posted April 4, 2019 Welcome to the Forums, Joanna... could you possibly shoot and upload some pix so we can see what kind of cracks you're getting? What is it that you are casting and how are you drying the pieces? Link to comment Share on other sites More sharing options...
Chilly Posted April 4, 2019 Report Share Posted April 4, 2019 What are your moulds made of? What type of clay are you using, thick lump stuff, or liquid slip? How are you drying the clay? Over how long a period of time? Link to comment Share on other sites More sharing options...
JoannaPardue Posted April 4, 2019 Author Report Share Posted April 4, 2019 Hi, I am using store bought liquid slip and plaster molds. Un-molding after leather hard and just letting air dry, usually 24 hours. This is an example and they all have multiple cracks like this. The more I do the more I research and the last slip i bought was super thick so i thinned it with just water and just discovered that was not good. Do you think this is why it is cracking? Link to comment Share on other sites More sharing options...
liambesaw Posted April 4, 2019 Report Share Posted April 4, 2019 Yeah you don't thin slip with water, you use darvan or some other deflocculant Link to comment Share on other sites More sharing options...
JoannaPardue Posted April 4, 2019 Author Report Share Posted April 4, 2019 So you think it made the cracks? Link to comment Share on other sites More sharing options...
liambesaw Posted April 4, 2019 Report Share Posted April 4, 2019 Yes I do, but I'm not professional. I just know from glaze and slip experience that water is the enemy Link to comment Share on other sites More sharing options...
JoannaPardue Posted April 4, 2019 Author Report Share Posted April 4, 2019 Thank you! Its quite a learning experience but i really like it. Link to comment Share on other sites More sharing options...
neilestrick Posted April 4, 2019 Report Share Posted April 4, 2019 Try getting them out of the molds sooner. If you let them sit too long in the mold they can crack as they shrink. The cracks may not be visible until they dry more, but changes are they're starting in the molds. Link to comment Share on other sites More sharing options...
Chilly Posted April 4, 2019 Report Share Posted April 4, 2019 As @neilestrick says. You need to get the moulds open as soon as you can. When is "as soon as" ? Hmmm, difficult, you will only tell by practice. You might need to crack the mould open, and then separate it and leave the clay in one of the parts of the mould as support. Pick a piece that doesn't have projections or undercuts. You might need to cast 2 or 5 or 10 times to get the feel of this, before you get a perfect casting. Think of this as like taking driving lessons. Many lessons, no actual journeys. Link to comment Share on other sites More sharing options...
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