Post #216026 by Rum Demon on Mon, Feb 20, 2006 9:39 AM

HMC, you did the exact right thing putting vaseline on the first half of your mold. It does need something else the two sides will be nearly impossible to part and you'll end up chipping and crumbling your mold as you struggle to open the damn thing. There are fancy mold releases and silicon sprays you can buy for this step, but petroleum jelly works pretty well and is much cheaper.

Have you opened the mold yet? I worry a bit about your keys. Instead of straight up and down, I use more of a tapered edged key: /\ If you've already opened your mold and all is fine, then it'll probably be ok. I just worry that one or two of your keys might stick and break off into it's "keyhole".

I'm also curious to see what your pour times are like.

Everyone else: Stone molds are dry and porous so when liquid clay is poured into them they immediately begin to pull the moisture out of your slip, leaving clay sticking nicely to it's surface. The longer you leave slip in a mold, the thicker the walls of your mug will be.

My usual pour time is about an hour. I read it should only be 15 minutes or so, but found that to be terribly insufficient. There have been a few times where I've gotten sidetracked and left slip in for two hours or more. These are some HEFTY mugs!

Also, I don't do much of anything to prepare the mold for the slip pour except spritz the inside surfaces with water to minimize bubbles. I'm told talc keeps the work from sticking to the sides but have never had a sticking problem. After pouring out the excess slip, I turn the mold upside down for a few minutes to keep the really liquid bits inside from settling too much to the bottom. Then I set the thing aside for about 12 hours or so, the clay dries and pulls itself away from the mold.

I'm not saying that any of this is the RIGHT way to do things, it's just what I've found works. I know of people who pull the mugs right out, but mine always collapse and/or deform if I pull them out too soon.

Then of course, you're on to cleanup......

So anyway, take lots of pictures of your next step! We all look forward to it!

take care,
-Joe