Release Agent?

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I can only answer to the use of PR not Alumilite. In the use of PR no release agent is needed. PR will shrink approx. 2-5% during curing.
 
Silicone molds don't require any release agents to be used with PR or Alumilite . PVC or CPVC molds don't require a release agent with PR due to the shrinkage of the PR as it cures (but it does help) however Alumilite don't shrink as it cures so a release agent is needed .
 
Silicone molds don't need mold release for most hobby urethanes as they do not contain aggressive solvents. Mold release helps one remove the mold after use as some urethanes have very little shrinkage.

If you are using polyester resins in silicone molds you should use mold release because the styrene solvent will, overtime, effect the silicone. The mold release is a barrier coat that helps the longevity/library life and usage of the silicone mold.
 
Glass Scratcher said:
Silicone molds don't need mold release for most hobby urethanes as they do not contain aggressive solvents. Mold release helps one remove the mold after use as some urethanes have very little shrinkage.

If you are using polyester resins in silicone molds you should use mold release because the styrene solvent will, overtime, effect the silicone. The mold release is a barrier coat that helps the longevity/library life and usage of the silicone mold.
Click to expand...

Charles good point I was starting to have my molds sticking and tearing in the top bridge area of the mold. I have been doing a LOT of casting and not using anything they where working great but now in the corners and thin areas there getting brittle and the resin is not releasing and tearing at the mold.

So I guess I should be using some type of release as a standard practice. I was afraid cause I did not want to contaminate my PR in any way.

Another question little different topic seams this one was answered.

Will silicone, Mold Max 30, stick to black rubber stoppers. I am going to be using black rubber stoppers in my mold and wondering do I need some type of release and what would you recommend that would be readily available if I do.

thanks
Bruce
 
That's why I love this place . I've run gallons of both PR and Alumilite through my Gadget molds and have never had any sticking problems but after this I will start to use some of the mixture that Charlie recommended . I use it in the PVC and the pill bottle molds all the time but didn't think it was needed in the silicone molds . Thanks guys !!!
 
bruce119 said:
Charles good point I was starting to have my molds sticking and tearing in the top bridge area of the mold. I have been doing a LOT of casting and not using anything they where working great but now in the corners and thin areas there getting brittle and the resin is not releasing and tearing at the mold.

So I guess I should be using some type of release as a standard practice. I was afraid cause I did not want to contaminate my PR in any way.

Another question little different topic seams this one was answered.

Will silicone, Mold Max 30, stick to black rubber stoppers. I am going to be using black rubber stoppers in my mold and wondering do I need some type of release and what would you recommend that would be readily available if I do.

thanks
Bruce
Click to expand...

Bruce,

You shouldn't need any barrier coat or sealant on the rubber stoppers unless they have a gread deal of tooth, and may form a mechanical bond. I've poured and spilled Mold Max on plastic, urethane, brass, painted steel, PVC, PR... The only things I have had a problem with were unsealed wood, cloth and paper. I keep a bottle of SuperSeal from Smooth-on, to give porous or questionable materials a spritz, let it dry, then spray with Ease Release or Stoner's mold release spray. Always remember to let the aerosol carriers air off(dry) for at least 15 minutes, before pouring silicone or resins as the carriers can react with the casting.

If you have some carnuba car wax you can buff that on the stoppers as well, don't use silicone cooking spray or silicone lubricants, as that can cause silicone to adhere more.
 
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