Clay cracks while forming unless soaking wet

[Mi_Wan]

I’m having issues with my clay. I source it from my garden in Nairobi, it’s a clay rich, red soil so getting the clay out is not the issue. When you go to work with it, it’s fine until you try to shape a coil, then it cracks everywhere. The only way to work with it is to make it so wet, it barely holds shape and you kinda have to have your hands in the vessel while you scrape the clay up into shape (this is the traditional way of doing it ). It’s fine for large vessels, but not ideal for small detail and carving (which is what I’m trying to do). Is there any way to make the clay work when it isn’t this wet or should I just accept the limitations of the clay and find another body? I’m frustrated but I don’t want to give up on it because I know it will look amazing in the end. Any suggestions are so appreciated.

 

[Min]

Clay that is splitting and cracking like you describe is "short" or "non plastic". Can you get bentonite or ball clay? I think you need to amend your clay by adding either of those. Have you fired your clay successfully for what you are trying to do? Also, does it need to hold water without leaking? Another thing that can lead to cracks while working with it it the water content being too low but that doesn't sound like your situation at all.

Welcome to the forum.

[Mi_Wan]

Thanks for the reply! I can indeed get my hands on bentonite, I’ll give it a shot as soon as possible. It fires beautifully and holds water really well. 

[Min]

It's hard, if not impossible, to mix dry bentonite into soft clay directly. I'ld suggest drying out a 1/2 kilo or so of it. It will take some testing to see how much bentonite is needed, ballpark around 2% should give you an idea of how much is needed. So if you want to test 500 grams of clay use 10 grams of bentonite. Slake the bentonite down in water, just sprinkle it onto around 200 mls of water then don't touch it, just leave it to slake for a few hours and  has settled to the bottom of the water. Break up the clay as best you can so it's not one solid lump then add water to your dry clay and slake it down to make a thick slurry then add  the slaked bentonite and mix it up really well, use enough water to be able to stir up the clay. Dry out the clay to a workable consistency and see if the 2% was enough.