Mold release problems...

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Zawoogie

Member
Joined
May 31, 2008
Messages
7
Location
Roseville, Michigan, USA.
I'm trying to cast bottle stopper blanks and I'm using PVC as a mold along with phenolic plastic as a base to the mold. The problem that I'm having is that the PVC will not release the mold once it sets up. Is there anything that I can put on the inside of the mold to allow the casting to release? I've let some of them set up for 4 days before trying to release them but I'm still having to use the band saw to slice down the length of the tube and peel it open. I have no problem with flat molds for pen blanks but stoppers are another story. Any suggestions? Thank you

Marty M. aka Woogie
 
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you can try silicone mold release, pam cooking spray, or spray paint the inside of the pvc.

These all work pretty good. With the spray paint the resin will stick to it and actually put a painted finish on your blank (nat that it matters because that will just get turned away anyways
 
I use pvc for stopper molds as well. For the base of the mold I use the pvc end caps and have not had a problem with them sticking. Once everything hardens I just pull off the end cap and the mold comes right out with it.
 
I use PVC for my molds and have never had to use a release agent to get them out sometimes if they have not fully cured they can be a bit hard to get out but i just let them sit for a little while longer and then they come right out
 
I've tried the PVC pipe for molds and it did not work. I've had to smash them out and some of them break on the way out. I wonder if there are different types of PVC pipe? I have one cast in my shop that has been sitting there for 3 weeks and the PR will not come out. I'm waiting to see how long if ever it will take to come out.
 
I've cast stopper blanks in PVC and pen blanks, if the pipe is new and fresh, it works better, after a few uses you sometimes have to coax them out, I've never used any kind of release.
 
I asked a friend of mine in the fiberglass business about mold release a while back. The pros (after getting the surface ultra-smooth) initially treat the mold with polyvinylacetate (PVA), and subsequently buff the mold with carnuba wax. The PVA is only needed once. The carnuba goes on before each use.

PVA mold release is available at many craft stores. Carnuba wax (my friend uses McGuires in the gold can) can be found at auto parts stores.

Regards,
Eric
 
Use the SCH 40 PVC. It has a thicker wall. My blanks release from the mold in about 45 minutes. I let them sit in the mold 10-15 more minutes to cool, then slide them out. I've used the same molds for 100 or so blanks with no release and they still work like new.
 
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