Help! Alumilite casting will not release from PVC

[rvanbeek]

First thanks for all the help in getting me this far. Curtis has been a great source of information regarding warming up the mold and preparation of the casting. So now I have mixed everything,, made a mold using 4" pvc, placed wood material in the mold and 50# of pressure. Left it in the mold 3 hours just to be sure of set up.

The casting will not release from the pvc. I put in in a vise under pressure to push the cast free but ended up breaking the pvc mold. I coated the inner surface of the mold with a cooking spray but that didn't seem to help. The base of the mold was cutting board material and there was no problem with that coming off.

I'm thinking that I may have buid a 4" square mold out of cutting board instead...

 

[jttheclockman]

Alumilite does not shrink like PR resin does so you may need to do a few things to your molds. There are numerous threads on this subject here if you do a search of the forum. This may help you. With that said i can mention a few of the methods used that some say work. There are a few that use PVC piping for their molds that split the pipe down the middle. Then the clamp with rubberbands or the like. Pour the material and when cured just split the molds again to get the core out.

Some people coat the inside of the pipe with mold release, Pam cooking spray, Mineral oil, Baby Powder, car waxes, and a few other goodies. Some people never have a problem and use nothing. Some use a combination of heat and cold to break the bond.

So you may have to experiment for yourself to see what works. I use Silmar 41 and never have this issue because as I said that resin shrinks enough to release it from the molds easily. Good luck.

 

[Dan Masshardt]

I like the silicone molds! Cutting boards work good too but blanks pop right out of the silicone.

 

[Willee]

Just a thought ... some time in the freezer might release it.

Willee

 

[triw51]

Or you could just put the piece pvc and all in the lathe and turn it off. I would not suggest trying to hammer it out it does not work learned that the hard way.

 

[rvanbeek]

Yup, the hammer doesn't work. I was hoping to be able to reuse these molds. Is there an effective mold release agent that I can use or is the pvc the problem.

 

[rvanbeek]

Dan.. where are you getting silicone molds from?

 

[BJohn]

From what I was told when learning that for PR resin use PVC as it will release. Alumilite will not.

 

[turncrazy43]

Rich, you can buy the silicone molds from PTownsubbie, (lov2turn.com). he also sells them thru ClassicNib.com. Both are IAP members and are great to deal with. Woodnwhimsies.com also sells the molds.
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Everyday I'm vertical is a great day

 

[BSea]

Alumilite will release. . . . . . . . Eventually. I did some solid black alumilite for sections & accents. It would not release, so I put it away in my garage. About 6 months later, it slid right out. I know that isn't what you want to hear, but that's my experience. I have been able to use a hammer with some success, but it's better to just turn it off. If I were doing this for my own use, then PVC is a cheap option. For about $3 you can buy a piece of PVC that will give you about 25 pieces. So it's less than 15¢ a blank, with some extra effort to get to the blank. But if you want to do this for production, then a mold from PTownsubbie is your best option.

 

[HamTurns]

Yup, the hammer doesn't work. I was hoping to be able to reuse these molds. Is there an effective mold release agent that I can use or is the pvc the problem.

I use PVC for casting Alumilite. When I started casting with PVC I'd split the PVC, then put a hose clamp on it. Now I don't split the PVC and just use either Stoner mold release or Vaseline. A tap with a hammer gets the casting out easily. I'm still using my original PVC pipes/tubes that I started with over two years ago.

New PVC has some mold release left in it from the manufacturing process, but that wears out after 2 or 3 castings.

Happy turning
Tom

 

[Fay Prozora]

I had a dilly of a time getting mine out too. I bought some mold making stuff and I did pour some amulite into a PVC pipe the size of a bottle stopper. I could for the life of me get the blank out so I tossed it. Then saw a video on making a mold so I fished that one out of the trash and will use it for a model and later I might do what another poster had said about leaving it alone for 6 months and see if it will come out. If it does then that might be fine. I did order a mold from Fred Wissen and it isn't here yet but it is coming. That will give me a few pens. Well I might put this in the freezer for a little bit too and then see. Maybe I will try the Vaseline. I'm always getting ideas and I'm sure some will work. Note to self,,, next payday, buy the PR resin.... Fay

 

[Displaced Canadian]

I spray a little silicone spray down the inside of the pipe, cast the blank. Then wait about 48 hours and soak them in hot water for about 45 seconds and use a dowel to tap them out. After a few times casting you may have to cut the mold off.