My english is terrible, but i hope that You will understand what i want to say.
I'm not an expert in casting and moulding, but i will write what i know. Maybe it will help.
Making mold:
When You are making a mold You have to remember that when You pour resin to it, some air bubble can appear (horrible bastards!! ;P). The best way to avoid it is to place miniature/monster/leg ect. in position that help to move air bubble (horrible bastards!!) up to intel (?? You know, the place where You pour resin ;P). You can also add some channels by which air bubble (horrible bastards!!) can leave mold.
1. first thing You have to do is to unbubble the silicon. i use vacuum pump. Remember that silicon can start to "boil" in this process. it is good to unbubble it in a much bigger container than a volume of silicon. (two time bigger, sometimes three)
2. pour silicon in to the box with miniature/monster/leg ect. and unbubble it again. Keep it in vacuum chamber for a while.
Casting:
And again ... air bubble (horrible bastards!!)
It's good thing for a start to use resin that have a long liquid life, You will see why below. There are two ways of casting:
With use of vacuum pump:
1. mix A and B parts. YEAH ! and unbubble this shake with use of vacuum pump. Do it quick.
2. pour resin to mold. I sometimes squeeze mold a little bit in places where are thin and long free spaces (like a sword).
3. it's not the end. Put all molds with resin in to vacuum chamber and unbubble it again (the resin can "boil" so remember to make a big intel (?? again .. You know, the place where You pour resin ;P). Don't keep it long there.
4. Pull molds out. The point is that resin have to be liquid during all four steps.
5. Pray for no air bublle (horrible bastards!!) ;P
With use of compressor:
The whole process looks the same as with use a vacuum pump. The difference is that resin don't "boil" during the whole process.
The problem is that i don't know is it a good thing to keep molds in pressure chamber for a long time. Now I'm experiment with it
.
Two more things. The vacuum pump is quite quiet, so it can be use in flat. The compressor is a loud monster that want to eat Your children and drink Your blood.
I hope it helps. If someone find some technical (or grammar
) mistakes let me know !
GOOD LUCK !!
