Does anyone ever de-gas their resin before mixing in catalyst?
I worked in a research and development lab at an adhesive company several years ago and we always de-gassed our resins (polyester included) before catalyzing.
It’s quite easy to de-gas. You put the bucket of resin into a little vacuum chamber and when air bubbles stop forming, it’s done.
Josh- if a resin sits long enough, won’t it de-gas (if not totally, mostly?) on its own?
More importantly, how did you and your colleagues deal with air-bubble injection during the mixing-in (of the catalyst) process? I would think this would be more critical since one mechanically introduces bubbles into the mix, and then has a limited time before the mix starts to set.
BTW- RR Epoxy is easy to de-gas once it is mixed; you put it a shallow container and then nuke it in a microwave for 5-7 seconds. This tip was conveyed to me by GL himself and reinforced by a number of users of his product. This technique has helped me tons in reducing air bubbles.
We didn’t generally de-gas the catalyzed resins mainly because the resins catalyze too fast for that. However, the uncatalyzed resins did sometimes have a considerable amount of gas in them.
This probably isn’t a major problem w/ poly since it’s not that viscous. I was mainly curious to know if anyone did this and if it made a difference. I wouldn’t think that anyone would do this because it wouldn’t make a huge difference in the end product and because so much air in introduced into the resin when it’s being worked into the cloth during lamination.
That microwaving tip is a good idea though. I’ll have to keep that one in mind if I ever work w/ epoxy.
One problem that plagues polyester is that even after degassing you still have gaps in the final cured resin because of evaporating styrene. This is the main reason polyester isn’t considered waterproof. Epoxies are generally high solids and don’t suffer from this. It’s also the reason epoxy boats don’t suffer from osmotic blisters.