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Discussion Starter #1
Hey all,

I wanted to play around with making some molds of rocks/wood to make fake stuff for vivs. Ideally... using smooth on materials would be ideal, but I'm not gonna shell out that kinda cash for a curiosity.

Many of you have probably seen this link before. He uses some kind of latex based glue.

I'm just trying to brainstorm what kind of products would be similar to that and are available on this side of the pond. There's a drylok formula that's latex based isn't there? Does anyone have any experience with that and if it stays very flexible and durable?

Any other ideas are most welcome.

Cheers.
 

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I would still go with smooth-on, you could do a simple a silicone with a plaster bandage jacket, the trial size Mold max stroke should be enough to do a few rocks. once you have that you can do a roto-cast with smooth cast 65D. then you have a detailed rock shell that you can paint or w/e
 

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you could just try with plain old silicon. like you use to seal tanks or the hardware store stuff. the clear stuff. just need some sort of mold release. would not be like the high end stuff you would get at polytech or smooth on. but you would save money.
 

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Discussion Starter #5
Interesting, thanks guys.

Do you know if local places carry any mold release type products like PVA or spray petroleums?
 

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Mushrooms and moisture

...oh, that kind of mold :)

Awesome idea, gotta make a how-to thread and show off the finished products. Skylsdale, IIRC Zbrinks, and a few others have posted fake rock/wood how-tos, you might get some helpful info from those. Can't remember if they used molds, but I dont think so.
 

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i got the info from an artist forum years ago. i have never used the info but hardware silicon would be cheaper and you could practice with it. about mold release, pretty much anything oily. vasaline i think was mentioned in the thread. or you could go to a crafts store and look for mold release stuff. they usually have mold making stuff in the store.
 

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so this thread got me doin a little experiment. using petroleum jelly and hardware silicone works to make a basic crude mold. a light coat of jelly applied then wiped off is enough release for it not to stick, bad thing is thick layer of silicone does not like to cure fast even with heat applied, 2-3 days. I only did a 1"x1" rock, Im planning on doin some bigger stuff sometime
 

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ive used plaster of paris to make molds of stuff before pretty cheap
im not so sure people want to hear about your past with plaster casters ;)

too heavy, and brittle. plus it has a very porous surface. if your slip casting clay, then its great, for casting pretty much anything else, your better off with some sort of silicone mold.

james
 

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especially if your going to do a rigid (resin) casting off it you want a soft(silicone) mold.
if i was casting something in silicone i would use a rigid mold(epoxy,fiberglass,etc)
 

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What I have found to be true in my mold casting experiences has been:

1 flexible
1 rigid = cast can come out of mold.

1 flexible
1 flexible = pain-in-the-butt, but possible if lots of release agent used

1 rigid
1 rigid = never coming out, unless it's in pieces or its an extremely basic mold, but then why bother at all?

I wish you luck with using the caulking silicone for a molding material. I tried that a few times about 6 years ago and could not get it work well. Perhaps you'll have better luck. My guess is that it will require many super thin layers like air dried latex molds do. I used too thick of a layer and got sticky uncured areas in the middle.
 
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