Howdy all! I'm new to the site, and been looking for a good community to learn from and perfect my stop-motion skills.
I'm working on my first short currently, and hit a speed bump recently with my casting. I have been following the steps on stop-motion magazine's site to cast in foam latex from my mold, and I'm using a foam latex kit from monstermakers.
Just tonight I attempted to cast my first character -- the smallest of four at 6 inches. Done at room temperature with about 50% humidity, my first batch of foam made within a minute was a solid, tough mass, and therefore couldn't be poured into the mold. Figuring to counter how quickly it set, for my second batch I spent a minute less time on the refining stage of the foam, (after the gelling agent had been added) and rushed to filling the mold. The foam latex remained liquid, and I was successful in filling my mold. After cooking it for 2 hours at 180 degrees, I took the mold out and popped it open to see how the puppet had cast.
To my dismay, the puppet looked rather collapsed -- some detail had come out nicely in the hands, but the foam itself was very weak and light. Upon poking areas of the puppet, its chest and face easily collapsed, and held their collapsed state rather than popping back to form. The in-between layer of excess foam was also INCREDIBLY frail and thin. However, the foam outside of the puppet on the mold itself had dried to a perfect consistency -- it held its form when prodded.
Due to my inexperience, I can't tell where I went wrong, and wanted to get some opinions before casting a third batch. Did I simply take the mold out of the oven too early? Or was my mistake perhaps somewhere during the mixing stages when I attempted to account for the first batch's toughness? Any advice would be extraordinarily helpful.
I've attached an image of the failed casting -- to get a sense of how the chest collapsed, that distorted ring on his belly is supposed to be a perfect circle.
This looks really good, and I would agree with Nick's repair advice.
One last thing. You could try using a rubber or plastic spatula, the kitchen sort used for getting everything out of a bowl, for putting the foam into the mould. That way you will not have to worry about damaging the mould surface if you touch it, and should be able to get the foam nicely in. But you have done very well to get it into the deep areas anyway.
You should be really pleased with the result so far.