Thread: Polyester resin stays tacky

Stick it in one of those little ovens for 20-30 mins at about 120C and Bob's your uncle.

Would be one of the most asked (and answered) questions about casting PR.

Thanks Big Shed, that's the first thing i tried though still as tacky as when it went in. might have to leave it longer. I'll give it a shot tonight.

p.s. anyone know where to get epoxy resin in Aus at a local place? like bunnings, etc. I just want a small quantity to try out and then if it's awesome
i'll order online from amcsupplies or somewhere

Originally Posted by curseddagger

Thanks Big Shed, that's the first thing i tried though still as tacky as when it went in. might have to leave it longer. I'll give it a shot tonight.

p.s. anyone know where to get epoxy resin in Aus at a local place? like bunnings, etc. I just want a small quantity to try out and then if it's awesome
i'll order online from amcsupplies or somewhere

You could try solidsolutions.com.au

Big Shed is on the money on the fix. The cause is usually too much moisture, from cast items or in air, and/or temperature to low.

Your local boat or fibreglass shop should have at least one or two brands of marine epoxy on the shelves.

You can also avoid the sticky finish by adding wax in styrene to the polyester mix. The wax comes to the surface during the cure process and leaves a stick free finish. The ratio is about 10cc per pint of polyester resin. This is the same process used to convert gelcoat to flowcoat.

steve

i also believe that a layer of glad wrap will also stop it ... i personally use the toaster oven ... it gives a much crisper look to the cast blank

Oven works for me too. About 100c for 20 minutes is what I do, once cool they are not sticky to touch.

you can also put the heatgun over it for 20-30 seconds.
Don't let it get to hot or it cracks.
but when it cools is just like the rest.

I also use the wax in styrene stuff, that works really well.

Thanks guys, a bit longer in the oven did the trick. I did two lots, one at 100c and one at 120c. The 120c resin cracked pretty bad at the edges but was still ok since the blank was a fair bit bigger than it needed to be. The 100c piece was perfect though it was the one that took the extra time in the oven.