Chris from Canada writes:
I am sure many of us have used part of a tube of sealer, closed and sealed it carefully before storing it for the next project, only to find a year or so later that it has hardened into a useless lump. Knowing realistically that you probably won't need it before it becomes useless, use it to replace those pricey commercial moulding products like Mold'n Pour or Fimo Flex. Here's the recipe:
1 part silicone sealer
1 part corn starch
Mineral spirits/paint thinner-enough to thin the mixture so it is thick like muffin or nut-loaf batter.
Work in a well-ventilated area, i.e. outside, in a garage with the door open a bit, under the stove vent with the fan running etc.... Put sealer and corn starch in roughly equal amounts into a disposable container (I used a disposable plastic cup) and then add a small amount of the liquid. Stir vigourously with a popsicle stick, or an old spoon or fork, adding more liquid gradually until it is the consistency of a smooth, very thick batter. It should be pourable with a bit of help from the mixing tool. If you add to much thinner by accident, just add more silicone and cornstarch (equal amounts) and stir again until smooth. And that's it.
If you've never made a mold before, check online as there are countless tuts out there, and the instructions are the same whether you are making a mold of a mosquito or a mastadon molar.
I used vaseline as my release agent for the original, and everything popped out like a dream. I didn't need anything for the copies because the mold is flexible. I experimented with just a tablespoon each of sealer and corn starch and about 1/2-3/4 tsp. of mineral spirits and ended up with enough to make a 1.5" square mold of a fancy button that I want to use to make ceiling medallions (or whatever you call the carved plaster circles that chandeliers used to be hung from). I cast one in plaster which looked great until I dropped it into the drain of the sink :-( and also tried it with air-dry clay and Fimo. These came out nicely too with very clear detail. The worst part is the vinegary smell while the stuff is being mixed and is curing, but once it is finished, there is little or no odour.
