# Cracks in clay :(



## Chrysaor (Jun 21, 2009)

Hi all,
Im sure someone has has this happen to them before, although Ive been on the forum for a couple of years now and posted the old 'Oh thats amazing!' comment to threads, Ive now found the time to get into doing some Halloween stuff (yes!)

I was sculpting a clay pumpkin the other day, Ive left it to dry but find it keeps cracking. I patch up the cracks and awake the next day to find more 

Im not sure if I should be leaving it out completely uncovered and letting it dry or if theres something Ive missed?
Ive left mini pumpkins out to dry and they have been fine, but this big one isnt happy and cracks.
What should I do?


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## Hauntiholik (May 17, 2006)

It's been a long time since I worked with clay but I remember allowing the clay to dry slowly with damp paper towels.


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## trentsketch (Jul 27, 2009)

You're using air dry clay? How are you patching the holes? Are you just adding more clay? I've always patched cracks by re-wetting the clay and smoothing it out.


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## Chrysaor (Jun 21, 2009)

Thanks Hauntiholik



trentsketch said:


> You're using air dry clay? How are you patching the holes? Are you just adding more clay? I've always patched cracks by re-wetting the clay and smoothing it out.


Im wetting the clay and adding more, Ive been out for a few hours and the parts Ive repatched have cracked again.
I thought maybe the house is to warm, and I put it in the garage, to which it cracked again.

I'll try adding paper towels to it as its drying and hope it stops cracking 

Thanks for the help both


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## Sawtooth Jack (Apr 9, 2011)

It's been a while since I've sculpted with clay as well, but you want to keep it covered (used to use plastic bags), and maybe spritz it with water if it starts to dry too quickly...but I'm talking old school clay, not any of the new air-dry or FX clays some of the sculptors out here use.


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## Dixie (Feb 18, 2009)

If it is air dry clay - it is just going to crack. I just used the search button and found the top 5 threads under "Clay cracks" were all people complaining of the cracks when using Air Dry clay like Crayola brand - and what they did to fix it.

It was too long of a list for me to post all the links here, but try the search button up at the top, and use "clay cracks" and check it out. Interesting stuff, a long with pictures, and text of what people did to get around it.

Good luck!


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## trentsketch (Jul 27, 2009)

I should go into a little more detail.

I check in on my air dry clay projects every couple hours looking for cracks. If I see one, I wet it and smooth it out before it's dry. I keep doing this until it actually is dry. After that, if there are cracks, I try piecing it back together with a wet paint brush and let that dry. If it still didn't work, only then will I wet the clay and patch it with a thin sheet of fresh clay. I smooth out the edges of the patch with the wet paint brush and let it dry. That normally does the trick.

I just did a custom set of cupcakes for someone that were a nightmare. The humidity kept changing and they were practically splitting down the middle. I just had to keep mending and mending until they were good enough to paint up and ship out. It's a back and forth battle when the clay wants to do that. You just need to keep at it.


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## Mr_Chicken (Nov 26, 2008)

What clay are you using? How thick is the clay?


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## Chrysaor (Jun 21, 2009)

Mr_Chicken said:


> What clay are you using? How thick is the clay?


It says on the bag: Cont net 1kg - 35.2 oz net wt.
Does that help?
Oh you can tell Im total noob at this!!!  lol

I appreciate everyones help. Ive got some deep cracks which Im going to try and fill in a mo, it appears to be dry all over now.

But at least I know for the next time to sculpt in the weekend when I can check on it every few hours and fix and repair if needed.

Whats the best type of clay to use, should I be using an oil based clay???


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## Mr_Chicken (Nov 26, 2008)

What I mean is how thick is your sculpt? And what kind of clay is it?

Only use an oil-based clay if you're going to mold it and cast it in something else. Otherwise, air dry or oven bake is the way to go.


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## TheOneAndOnlyKelly (May 7, 2009)

From my experience with the air clay, the wetter you get it, the thinner it gets and is prone to cracking. Air clay is not like regular clay. I'm avoiding that stuff in the future, there in nothing but heartbreak in it...


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## Chrysaor (Jun 21, 2009)

Mr Chicken it was air drying clay, its finally stopped cracking now, I had to patch a few more cracks up.
Just got to find something to sand the lumps and bumps I seem to have
I tried to do it with a tool when it was still wet, looks like I didnt make a good enough job.
Im going to have to get my head around using clay and whats good for what


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## hauntedkimmy (May 31, 2011)

I use air dry clay only for sculpting a project that will eventually become a mold of something. I keep it airtight and wrapped the entire time until I cast it just so it doesn't crack. In my humble experience with air dry clay, it will just crack no matter what. It shrinks during the drying process, so the wetter you piece was when sculpts, the easier it will crack as it dries.


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## angelor (Jun 21, 2011)

Years ago I used to sculpt puppets. When making a head I would start with a styro ball and sculpt on that. make a stand out of a block of wood and a dowel. Use bakable clay and leave a few areas of foam exposed, like the eyes of your pumpkin. take it off the stand and bake as directed for the type of clay. The styro ball will melt away leaving a hollow shell. Remember to vent the air, melting styro gives off toxic fumes.


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## Chrysaor (Jun 21, 2009)

Mr_Chicken said:


> What I mean is how thick is your sculpt? And what kind of clay is it?
> 
> Only use an oil-based clay if you're going to mold it and cast it in something else. Otherwise, air dry or oven bake is the way to go.


Oh sorry MrC, its about half an inch (approx) thick, its finally stopped cracking and Ive started to sand it down.
I think I'll be using oil based clay next time.

Do you have to bake oil based clay??? Sorry I'm not sure what clays I can use for what


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## playfx (Mar 10, 2007)

In a nutshell.

Water based clays are more for air or kiln drying, easy to work and clean up. If your working a sculpt more than a day it need to be sprayed with a light coat of water and coverd up with plastic. Some water clay Like WED are used to sculpt and mold over with ultra cal or silicone so it can be reused. Water clays are farly cheep.

Oil based clay are use more for making a sculpt and molding over it with something like ultra cal or silicone. If you put it in the oven it will just soften and melt. Some oil clays have sulfur and can't be use with silicone so you have to watch what you get. Working with oil clay you need some type of chemical to smooth it and for clean up. Oil clays can cost.

Poly clays like sculpy are more for sculpting small projects and baking in the oven.


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## BioHazardCustoms (Aug 5, 2009)

We use WED clay when sculpting masks and prosthetics. You have to keep a spray bottle handy, because the stuff cracks at the first sign of a breeze. Until you make your mold from ultracal 30.


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## divinedragon7 (May 29, 2009)

i've had clay crack because it was to thin, i used normal white glue to fill in the cracks, then painted the glue a deep red color so it looks like my projects spliting open.


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