First Rock attempt questions?? PIc

[Beckham]

So I decided I would try the JKnuth method on this rock. I used two tubes of silicone caulking on it and it still feels a little weak??? Do you guys usually make a mother mold for rocks of this size or do you just add another tube of caulking to strengthen it? Any help would be great!!

Thanks.

[Vince Spellane]

I like to use plasti paste from smooth on for a hard shell.  You could also try cheese cloth in your layer for support as an alternative, but I like the hard shell for a rock that size.

[Kerby Ross]

On rocks I prefer Latex 74 (cheaper than the tubes of silicone) and after a few coats I reinforce it with fiberglass cloth or matte.  Still flexible but retains it shape better.  And all I need for mold release is car wax.



Kerby...

[outdoorzman]

I've used the silicone tube method quite a bit.  I don't do much molding/casting and it's cheaper than buying small volumes of tin or platinum cured silicone.  I like that you don't need a release agent of any sort.  For casting a few simple rocks, it works well for me.  To strengthen the mold I mix up some fiberglass resin with cabosil to a spreadable consitency and make a jacket that covers about 2/3rds of the mold.  Something else to try with this method is casting fish heads; using it takes some finese though, to get a good mold.