Anyone have any prep tips for sealing concrete before molding with silicone? I'm looking for a way that won't kill the texture I've got going on.
Best way to seal concrete before molding?
- Thread starter ThrowingChicken
- Start date
jedimaster
Sr Member
I've used both Pavex and bondcrete before to seal concrete.
robstyle
Master Member
you can coat the concrete in melted Vaseline or car wax with a chip brush. You may want to add a little acetone or alcohol to the mix to keep it thin. You must melt it BEFORE it is applied. That is unless you want it to look like a smooth cake by heating the stuff up after its applied to the concrete.
tango'd fett
Well-Known Member
PVA would do the trick too , unibond here in the UK amongst many names, but you could paint or spray it on and it can be thinned with water.
Hrm, thanks for the tips! Has anyone tried this stuff from Smooth-on? http://www.smooth-on.com/index.php?cPath=9_1123_1299
exoray
Master Member
Never tried Smooth-Ons version but I have used other brands, it's like KY jelly and I wasn't real fond of it...
You might try a 'grout sealer' or 'stone sealer' (in the tile area of the hardware store) but do it on a test piece first and verify that the silicone won't react or stick to it as most 'grout sealers' are silicone based... You might end up with that silicone to silicone bond, that being a very bad thing... If it doesn't stick you should be golden as grout sealer doesn't mess with the surface texture but will make water bead like it's on a sheet of glass...
I have done the Vaseline thing before, it works well but you end up with a greasy color changed original... I double boil the Vaseline to liquid, brush it on with one hand while I follow around with a hair dryer in the other hand to make sure it stays liquid until it soaks in, or I can blot it off with paper towels...
I won't need the original to last past the molding stage, in fact I don't expect a few areas to survive, so the Vaseline method might be a nice and cheep way to go.
robstyle
Master Member
You should be able to simply melt the Vaseline inside the container with a hair dryer or heat gun then brush it on. The surface of the cast piece should come out shiney but this can work for you as it gives depth when painted. When doing concrete blocks, I always add a dusting baby powder to the paint while its still tacky then dust it with matte finish. Before the blocks would be used, they are dusted yet again with baby powder. Its very convincing.
tango'd fett
Well-Known Member
Melting vaseline and baby oil , i dont like where this thread seems to be going !!:lol
:lol Should have been with me when I had to buy 8 big tubs of Vaseline for a big mold. Lots of strange looks from the checker.
