Alternatives for Mold Release Agents

Skaught

Sr Member
Is there any commong item that can be used as a mold release agent for a silicone mold? I know vaseline can be used, but last time I did that it left brush strokes in the final piece. What about non-stick cooking spray? :)

Scott
 
Lord, don't tell me you brushed in vas ALONE into
a mold... Eww what a mess that would make... :confused

Next time mix it with NAPHTA and paint the
molds with it. All the release agent you'll need... :thumbsup
 
I've never actually put mold release -on- the piece that was being molded. I usually brush Vicks vapo-rub (essentially vaseline) on the silicon around the piece that way the next half of the mold doesn't stick to itself. If any gets on the piece, I wipe it off with a cotton swab. Out of curiosity, what are you trying to mold?
 
No mold release is needed for silicone rubber. If you are asking about a release when making a multiple part mold, so rubber doesn't stick to rubber, vaseline is the stuff. Use a wide, flat brush to apply the vaseline so it is just a film, no streaks. Do this just before you pour the rubber or the vaseline will dry out.

The reason using a mold release is useless is that nothing sticks to silicone rubber. You can put a layer of spray paint in a mold and then pour the material and you'll see the paint pulls loose by how the paint appears on the casting.

Scott
 
I'm pouring the silicone over plastic mainly, and it will hit some clay and a wood box frame. I didn't think I really needed it, but all the demo videos show it being used.

Scott
 
As long as the clay isn't sulfer based so it won't react with the silicone you should be fine. I've used Smooth-On's Universal mold release spray.
 
The bummer with the brush on stuff, as per the OP, is that it can leave brush marks and pool up in nooks and crannies. I JUST wrote a blog entry related to this topic and recommended this stuff:

Ease Release® 200 | Silicone Rubber, Urethane Rubber, Liquid Plastic, Casting Resin, Lifecasting, Epoxy Resin, Rigid and Flexible Foam from Smooth-On

It's basically a spray on vaseline. Works really well, and conforms PERFECTLY to the shape of whatever you're spraying on. So no brush marks, not bristles, no pooling.

Here's the blog entry if you want more details:
The Project Work Bench: Reader Mailbag
 
Sorry for the necro-post guys, but I have a related question and I can't seem to find info anywhere else. I have a plastic form that I want to pour urethane foam into (Smooth-On Foam It 10 slow). Can I use vaseline as a release agent on the plastic? Note: I'm not really concerned with brush strokes showing up in the pull. Any help would be greatly appreciated, thanks!
 
Vaseline should work fine. It gives a good barrier but will leave brush marks, if you aren't bothered by that then go right ahead!
 
So I tried the vaseline and it worked ok...one small section bonded pretty fiercely and stayed on the plastic...it should be noted though that I only used a VERY thin layer of it. I'm thinking of having another go at it, but with a thicker layer. One thing I did want to share that I noticed is that due to the heat (I believe) from the curing process, it 'melted' the vaseline, cause that surface came out super smooth. I was very pleased with the results.
 
One cautionary tale on Vaseline... it is a petroleum-based product, silicones are petroleum-based products, which means they like to absorb more petroleum into themselves which can equal swelling or poor tear strength over time! Just an FYI
 
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