Molds from plexiglass

[bitshird]

I just got a pint of polyester casting resin to try, a couple of things are confusing .
1 the thicker the mold, the less catalyst you add? it says for a 3/4 inch thick cast use 5 drops per OZ. with a 1/8th thick cast use 15 drops per OZ, does this sound logical?
2 I have several square feet of Acrylic sheet, I also have some silicone mold release, if I glue up some molds say about 3/4 square by 5 1/2 inches long, and spray the inside good with the silicone do you think the Polyester resin will come out.
I found the one about ribbon casting looks interesting
Ken Ferrell

 

[its_virgil]

Thicker translates to less catalyst because thicker will get hotter and heat is the medium to cure polyester resin. The catalyst is the agent that reacts with the resin to create heat. More catalyst means more heat. So, as the castings get thicker, the amount of catalyst needs to be reduced.
Ken,

I cast snake skin blanks which are 5/8 ths, 3/4 ths, and 7/8 ths of an inch thick. I use 3 drops per ounce and the stuff does just fine.

There are several threads on casting and mold making.

There are several articles in the library re: resin casting. More articles can be found in the Y! PT files and some of those are duplicated at http://www.penmakersguild.com

Do a good turn daily!
Don

 

[gketell]

Acrylic softens with heat. PR heats as it cures. Do the critical temperatures of the two cross? I don't know. But I would do your first cast in a bowl to be safe. [}]

GK

 

[mwenman]

What does work as a mold is if you can find some 1/2" thick Polyethelene cutting boards. the kind your mom, wife, significant other may have in the kitchen and NO don't use hers..go to Wal-Mart / Alco etc and get your own. Also get some #6 x 3/4" or #6 x 1" sheetmetal screws, and a tube of kitchen / bathroom silicone caulking.

now just cut a bottom, 2 sides and 2 end pieces. Drill a few pilot holes along the sides and ends. Lay down a beat of caulking and screw the mold together. Wait the recommended 72 hours for the caulking to cure, them mix the PR, pour and wait for it to finish cooking. turn the mold over and the PR slides right out without having to use any release agent. could use some anyway if you want. PAM Original cooking spray seems to work well.

 

[fstepanski]

I'm making a couple molds from corian. Picked some up from a kitchen cabinet shop going out of business.

 

[MesquiteMan]

Actually you can skip the caulk and it will work just fine. You might get a tiny bit of leak on the first cast but after that the holes will be plugged just fine with the resin.