just a quick question regarding the above, what kind of filler material is best to use with these materials to help stop shrinking? or at least keep it to a minimum? 

also is it worth using a polyester tooling gelcoat as oposed to a normal gel coat?

Hi,

If you want to make a polyester part, then polyester gelcoat is suitable.

If you want to make an epoxy part, using polyester mold gelcoat is not the best idea. You have more risks to have "stickers". If you already have a polyester gelcoated mold and want to make an epoxy part, you need to wait for it to let all the styrene go away (when it does not smell anything anymore), which can take a long period. And waxing way more than what you would do normally.

Ideally, you want to use epoxy mold gelcoat for an epoxy part. Or use this from EC. Proven to work really well and it is epoxy compatible.

Hope it helps.

 



 


    A $1000 electronic device will always protect a 10 cents fuse

I've made some quite large moulds in polyester.  You get resins like optimold and other low shinkage reisns but they cost!  I've used a regular resin with good results.  From my experience it seems to be down to controling the exotherm.  I made up my molds one layer at a time letting each layer cure before keying and applying the next.  I'm also careful to maintain a low resin ratio (with full wetting) in the laminate. 

I think the shrinkage comes from laying up a thick laminate in one go.  It gets hot, cures and then contracts as it cools.  Just my thought mind.  Might be waaaaay off.

If you're moulding in epoxy from polyester use a good 15 coats of wax.

i've got no problems using anything that ec supplies but i live in a far off land now where big squirels bounce along and time seems to be 10 years behind the rest of the world lol, supplying this wierd far off land seems to be nigh on impossible as costs are high to say the least.

i read somewhere that using a filler material in polyester resin helps it not shrink, how true this is i have no idea but after watching the instructional video many times matt say's that the resin in the last 4 coats is a filled resin is this to help stop shrinking?

I've no idea on fillers, I've always just used straight PE resins.

polyester will shrink more than any other resin !! i use a vynilester resin which next to nothing and quite cheap compare to epoxy gel coat