Does mold release cause problems?

[Russknan]

I am relatively new to casting, and have done about 10 casts +/-. I have cast with wood, acorn caps, seed pods, and a pine cone. The first number of casts went without a hitch - excluding the occasional air pocket - but some of the later ones have come out sticky and oozing. Then, the other day, I took a tagua nut, drilled holes in it, mixed up some Alumilite in a plastic "rocks" glass, dunked in the nut and put the whole business into the pressure pot. When I took it out and started to pull off the plastic and turn, no oozing! I then realized that I had probably used mold release on the cutting board molds before casting the "problem" blanks. Hadn't done this with the earlier ones, but found it somewhat difficult to detach them from the mold parts. This may be a "duh" to more experienced casters, or I may not have stirred properly, etc. Anyone have insights or recommendations? Russ

 

[Jim Burr]

Alumilite doesn't shrink to the extent that PR does so a release agent isn't quite as necessary with PR. If you are using cutting board molds...just unscrew them and there ya go!

 

[Russknan]

Thanks, Jim! Russ

 

[resinman]

I use mold release a lot and have no problems. Sounds to me that you didn.t stir long enough.
When you think you have stirred enough, stir some more. Seven minutes open time is really longer than you think.

Alumilite Clear cures by creating it's own heat. The smaller amount you use, the longer it takes to cure. Pen blanks should be cured around 45 minutes. Yesterday I poured some very small ice fishing jigs for panfish. An hour later, they were still very sticky and soft. It took about 4 hours for them to cure.
Hope this helps.

 

[HamTurns]

I use Alumilite and cutting board molds along with Stoner mold release. I also use vasaline for mold release and to seal up the slits I cut in PVC pipe that I use for casting molds. I'll usually hold those pvc pipes in a hole drilled into a block of wood and I smear vasaline on the wood parts too, it's been working well for me.

I have not had a problem with or because of the mold release or vasaline, but I have had "sticky" parts come out of the mold before. It was absolutely because of not mixing enough.

I'm going to start using a small mixer for stirring and see how that works out for me. I asked Curtis about this and he said that he's used a mixer with success.

Good luck and Happy Turning

 

[steve worcester]

The only way I know of mold release inhibiting the cure of the Alumilite is using the wrong release.
If you are trying to release from a mold, use the appropriate release for that mold. Vaseline, potters soap, and poly or silicone mold releases would all be used for different molds. You kind of have to pick the release for the mold and the casting product.