don't want to start a fight...

[MDWine]

My question is about casting the bottle stopper...

We've used regular PVC pipe of the proper diameter (1.5"?) to make stopper blanks... We've not had any problems getting the cast out of the PVC mould...

Is the silicon variety any better?? why?

Just curious

 

[ed4copies]

Michael,

If your blanks are releasing from the PVC, I'd "stick with it" (pun intended).

For US, the darn thing becomes one with the PVC. The silicon square molds have been great for casting clear (that's all we have used them for, til now).

NO fight - just what we have done!

 

[Draken]

If you cast without pressure, the PR shrinks a bit from the mold, releasing from the PVC pipe nicely. Add pressure to the mix, and the PR can not longer shrink from the mold, making it VERY difficult to remove. The silicone, being flexible, would still allow for the easy removal of the blank cast under pressure.

I've also has some blanks cure too hot, and the heat deformed the PVC. Those had to be cut off. [xx(]

 

[SuperDave]

What about a mold release agent for the PVC?

 

[masterdcraft]

MDWine

I had some issues with PVC as well.

I found these so called golf ball holders (polypropylene) to use as molds. Item #: 0741-07SP
4 oz - 1 3/4 x 3 1/2 they have oz & ml mark lines as well

They work great, clear, release smooth, and price is ok.

Here is the website, you could find similar in sport stores.

http://www.sks-bottle.com/340c/fin24d.html

I like these because of the bottom, it has a center indent(photo) which helps when drilling.

You can view the stoppers on my album if you wish.

Hope this is useful.

 

[Sylvanite]

I cast under pressure, using pvc pipe for molds.

I turned tenons on blocks of delrin such that they jam-fit into a 1 1/2" pvc pipe. It's tough to see, but I left a small spike in the center which gives the casting a dimple in the center for a drill guide.

I jam the pipe onto the base, fill it with polyester resin, and let it cure in the pressure pot. Once it has set, I pop the base off, and push the casting out with a piece of broom-handle. I have mold-release agent, but have not used it.

I don't doubt that silicone molds would be nicer, but I'm satisfied with the pvc/delrin ones.

Regards,
Eric