Ugh! 2 Part moulds

ManicMan

ManicMan

Lord
Right.. my latest practice/learn to sculpt messing about I've been pretty happy with. And I kinda wanna do a cast of it so I'm gonna make a silicon mould for it.. first problem, the design is such that it... well, the only way I've worked it out is as a 2 part mould and I HATE trying to make them. They rarely work out well..

Part of the problem is I don't wanna waste something like clay which is single use for the bed.. So I have used playdough.. that isn't too bad but is take along time to clean it from the silicone.. it's not fantastic like that. and the model ends up coming OUT of the first half of the mould which kinda ruins it. So I went to check a couple of old videos but youtube is playing silly buggers with me and won't let me fine them right now ¬_¬

So.. for some stupid reason, I thought "Hey! Hot glue!".. this was a huge mistake.. I decided instead of testing it out on my lovely sculpt (well.. the lower legs could be better but it's pretty nice in my mind) I though mm, I got an old (or more bits of) skeleton armies plastic chariot which I wanna do up for fun.. I have one wheel with spike but not the other, so I can just make a copy of it.. well.. I now have a slightly misshapen wheel.. cause hot glue is HOT. Gonna have to try a hot air gun to fix it.. mostly just one spoke has shrunk, though this does give a flat edge to sit on the floor better ^_^;

I did think about just one-piece moulding it and then split the mould, but for the figure, I think it's a bit harder due to design (couldn't really avoid that). Need to think and any suggestions welcome ^_^ it's a multi-putt and green stuff sculpt.
 
ManicMan said:
So I have used playdough.. that isn't too bad but is take along time to clean it from the silicone.. it's not fantastic like that.
Click to expand...

Not that it was a total success, but I did it that way in the past, and brushed heated (to make it more fluid) Vaseline (petroleum jelly...?) on the play dough before pouring the silicone. This prevented the play dough sticking to the silicone.
 
maybe. It's the same kinda thing.. though I think Vaseline isn't even the same now cause I think they removed the oil. I did use liquid hand soap once.. can't remember how that went.
 
Pour the mould in one go then use a scalpel to cut the seam line and remove the original. This is a much better and far more common practice for small objects as you don't get the flashing that's hard to avoid with a clay bed. Use small strokes of the blade to create a serrated cut, that will help 'key' the two halves of the mould so they don't slip. Don't cut the mould completely in half, just down one side far enough to easily remove the master.
 
yeah, I just thought with this it would be a pain to try to get that cut right but hopefully I can get it to work.. Have to sort out the mould box and make some channels. Already a pain to try to work out the best angle for the split.
 
Right, not much update yesterday cause even once I appeared set and I waited a few more hours and took it out of the box, I still wanted it let it set for a bit longer. So Today I took to hacking and not bad. not greatly keyed but pretty well with the one side only cut.

I tried a quick Metal cast with it and not too bad. Not a successful cast as it was a tiny bit too fast (as in, I should have waited for the metal to heat up a tiny bit more.. I can get a temperature control thing but I can't see the point with the little I do ^_^ Just a couple of bits didn't join right (a leg fell off when demoulding.

I'll be doing another cast probably tomorrow and I'll try to get it painted up too ^_^
 
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