Use again and again ??? That sound just like thing I need !!! I am not caster, and purchasing whole package of silicone rubber is just too expensive to copy a head or two - good part of the rubber usually hardens before I use it...
Sounds too good to be true...
Can You give us some more info ? Is it elastic enough for one part molds or is stiff and only two part molds are possible ? How long it dries ?
Darko, yes this stuff can actually be used again and again. Over time it captures dust and dirt and becomes less clear, but so far this has not changed its properties.
When hard it has the firmness of thick rubber. It becomes soft after lying in hot water for a few minutes. Then it is like a big blob of chewing gum for one or two minutes, which is when you'd have to push it over the item you want to make a mold of. It hardens by cooling down. I let it rest for 10-15 minutes. After that it is again like rubber, but flexible enough to squeeze out the original part.
The material doesn't change or harden chemically, its properties change reversibly with temperature. You can keep cycling the material, it really is easy to use.
It definitely is strong enough for one part molds, but two part ones are possible. However, it is less flexible than a silicone mold, so casting a head should probably be done using a two part mold. An altrnative would be to encase the whole head in soft mold material, let harden, and then cut it open to remove the original. This wil give you a seam, but is perhaps the easiest to try.
This stuff's charms are its low cost and simple use. Downside is that it doesn't give you the perfection of silicone molds, mainly because it can be hard to get the soft material to totally and evenly enclose the part you want to copy. Water drops get caught and there are seams where two flows of goo meet up. So the more complex shape to copy, the more post-processing is involved.
However, Given its low cost I would definitely give it it try for your purpose. Warmly recommended.
Cheers,
Adrian