I am going to buy some quantity of Derakane 470-30 epoxy vinylester resin. This is a high-temperature resistant resin. I need it to make an exhaust heatshield for a kitcar.Problem is that this resin contains 33% styrene. Do you think i will have problems if i use vacuum bagging? I have read that vacuum bagging is not recommended with polyester because the vacuum will absorb the styrene of te resin and inhibit cure. What do you think?
I have bagged polyester and infused with vinylesters and never had a problem. I think you should be fine. You can always request a sample first before buying.
Usually PER cures too fast or is too thick to flow for VIP.
I’ve found with VER I need to ensure the pump doesn’t run all the time when I’m bagging parts, else it does suck the styrene out. To fix this, I use a vac switch to control the pump. Vacs down to 29", turns the pump off. Due to small leaks in the bag or whatever, eventually the pump comes on again (for about one second), and then the cycle starts again. It’s the pressure, not the pump, doing the work, so no need for the pump to run all the time.
It is an interesting “problem” vacuum bagging polyester composites.
The resin cures so fast. It kinda seems an envelope style bag would be a good idea with polyester resin because one could quickly shove the mold with wet lay up into the ready made bag and then vacuum it off fast. Where with mold flanges and sticky tape with vacuum bag applied over the sticky tape… that takes a lot of time to get right and by that time the polyester or vinylester resin has usually b-staged before vacuum is applied.
Anyone have tricks for vacuum bagging using polyester or vinylester resin? Only idea i can think of is to use less catalyst… maybe just 1% mekp?