Food-Safe Plastic?

Checksum

Member
I realize that this topic might not fit in the "general modeling" forum but its the closest to what I am trying to do... So
I am looking to make some custom Ice Cube Trays of various shapes that are just not available anywhere. My question is about what to use to make a food-safe mold. I have some Smooth-Cast 305 but Im pretty sure thats not food safe. I would like the trays to end up being a semi-hard plastic rather than silicone. Has anyone ever tried this?
Thanks,
Checksum
 
I would use the food safe silicone. and make a rigid base for the silicone. almost like a jacket for a regular mold. you could just get some MDF and make a small low profile box for them. simple and cheap.


Al
 
Is there such a thing as food grade plastic? I mean in relation to making a mold with. Do they make anything that you could use to make a tray? I would rather not use silicone because I have heard really bad reviews about silicone and Ice cube trays as the Ice gets stuck in the mold and wont release and you end up tearing or ripping a hole in the silicone...
 
I was gonna say vacuform as well, but SeismicA beat me to it. PETG has a little flex to it so it should work pretty well.

Just remember: No undercuts! You'd want plenty of draft on your patterns anyway for ice cubes.
 
Vac forming is a good way to do it. I didn't mention it because I figured what ever you wanted to mold had more detail than vac forming would pick up. but its a good way to if theres not a lot of detail needed.
 
Hey guys,
I have been thinking and I would prefer to stay away from vacuforming as well. I still want to cast it in plastic. Is there any reason why I cant just skip using silicone at all and use a version of smoothcast that is food grade? Basically making a mold out of hard plastic. Im not worried about ruining my subjects. Which will be golf ball sized rocks or a rock that looks like a diamond or a ruby with the facets.
 
The vac form idea is good - you can made a hard mold out of Smooth-Cast 385 then form the food-safe sheet plastic over it.

Here's the lesson to learn - what's the technical difference between the Smooth-Cast stuff and Kydex, besides the obvious sheet versus liquid part?

Thermoplastic vs Thermoset.
THERMOPLASTIC: Kydex, PETG, ABS, HDPE, Acrylic.. all that stuff is in the thermoplastic bucket. It forms with heat - basically, forming it is a process of controlled melt. The heat is external. You apply it.
THERMOSET: Epoxy, Urethane, Polyester.. those are all thermosets. They generate heat as a by product of the chemical process when you mix the two components together. Big word here is exotherm.

You won't melt and pour a thermoplastic with any predictable measure of success or injection molding wouldn't have been necessary, and you aren't going to melt a thermoset for any useful purpose at all except "because I wanted to".
 
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