pvc molds

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sgimbel

sgimbel

Member
Joined
Dec 23, 2008
Messages
675
Location
Round Rock, Texas
Do I need some sort of mold release if using pvc pipe? I did a 3/4" (gray, it was a riser) with Silmar 41 and I can't get it out. I checked the library and couldn't find anything.
 
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Mold release would be necessary unless you are using trays designed for casting (in my experience, at least). I use Stoner mold release whenever I cast.
 
I used to have the same problem...Now I put the pvc in my vise and tighten it up just a little to break the surface tension then use a metal rod againt the PR and bump it against the vise...and away she goes!:biggrin:
 
Where would I get mold release? I want to do some bottle stoppers also. Just going my first cast and so far I really happy with how there coming out. I purchased 1 mold here.
 
Scott,
Try to slide some Parchment paper in the mold between the PVC and the resin. I use the standard PVC with a "parchment lining"

Or wipe it with PAM
 
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sgimbel said:
Where would I get mold release? I want to do some bottle stoppers also. Just going my first cast and so far I really happy with how there coming out. I purchased 1 mold here.
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I purchased mine from TAP Plastics. I'm sure that you can find a cheaper source though. I believe any arts/crafts store would carry it; maybe even hobby store. Here is a Micheals in Round Rock:

3021 S IH-35, Ste 190
Round Rock, TX 78664
 
If you're using 5/8" pipe or larger, you should only need to flex the pipe a bit to get the blank loose. You'll hear it "cracking" itself loose. Then use a dowel or something to push it out.

With smaller pipe (I do a lot of 1/2" for slim sized blanks) you almost always have to knock it out with a dowel and a mallet. Post curing in the mold will help, though.

I haven't used mold release on pipes in forever. I only use it on the silicone molds I've bought from Gadget and NewLondon88 just because I don't want to accidentally tear the mold as they age. They're not as cheap as the pipe.
 
You don't need any release for PVC as long as you use the SCH 40. Mine always fell out when I flipped them over. They should shrink to reveal a 1/64" or so gap all the way around the blank. If I had some resin, I could show you what I mean. Let me see if I can find a blank and an old mold...
 
AceMrFixIt said:
Yes, CPVC can take the heat since it is made for hot water. PVC is for cold water and tends to deform when heated. CPVC is a tan color. I have been using CPVC from the start and none of the pipes have deformed.
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Maybe that was my problem.... Even with a mold release, the resin seemed to eventually eat away the inside surface finish of PVC and "etch" it. After that there was just no getting the cured PR out of the mold.

I need special mold sizes from time to time, I will have to give CPVC a try! Thanks Rick!! :)
 
I use PVC(white) all the time for molds and use vasoline, works great. Just smear it on the mold and when it cures it comes right out.
 
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