silmar 41 / curing / brittleness

[SantaEric]

using silmar 41 right now and 4 drops per oz into mold. taking about 14 to 20 hours to cure enough to demold with confidence...i've heard that by adding more drops per oz increases brittleness so i've resisted adding my drops...is there a "" break even point where i can add X amt more before brittleness is a real problem?

 

[jttheclockman]

Unless you are adding colorant you start getting into the 8 or 9 drop area then things start to get a bit brittle.

 

[brownsfn2]

The more drops per ounce the more brittle it can get. I usually stick around 3-4 drops per ounce. Sound like you are about right. I usually leave mine under pressure for a full 24 hours and then some. I think the less brittle they are the more fun they are to turn. Good luck.

 

[JohnU]

I agree with Ron. Stick to about 3 drops per ounce for a safe level of brittleness. Try warming your resin with a light in a heat box or an ultrasonic heater before adding your drops of hardener. Also, place the pressure tank in a warm area. It will still take 15-14 hours to cure but being warm will thin the resin, mix better and allow air to float up and out better.
Hope this helps, good luck!

 

[JohnU]

Sorry about the typo. My last post should read 15-24 hours.

 

[SantaEric]

thank you all...sounds peachy

 

[brownsfn2]

John makes a good point about heating. I usually warm the resin as well before pouring. It just seems to pour and cure better.

 

[hanau]

I do about 6 drops per oz.
Put it under 55psi of pressure and let it sit over night.
Then it usually sits around the shops a couple days before i turn it.
the outer layer stays a little tacky. but it is solid after turning the outer layer off.

 

[BSea]

For clear tube on casting, I use 3 drops per ounce. For color casting with multiple colors, I use 4 drops per ounce. I don't use pressure though. And like John said, warming your resin will help.

 

[hanau]

sounds like i need to cut down on the hardener.