I performed a full-scale experimented with the polyester resin as an alternative to the epoxy resin I'd developed an allergy to, but it was inconclusive. The result on cloth is more like flacid oil cloth than anything substantial that has inherent structure and holds a shape. There's little weight to the result, so it won't hang and drape properly.
Added to that, the smell is overpowering - I had to remove the curing cloth from the house after complaints from Hay.
I performed the experiment on Monday afternoon and by Tuesday morning it was still quite pliable.
I tried using the heat gun to make it drape, but to no avail - the heat simply made it more rubbery and less willing to drape. I did however touch the hot metal of the heat gun and managed to weld some polyester to my palm.
By yesterday it had reached a stage where it was reasonably hard, although nowhere near as hard as epoxy. I could try thickening the polyvinyl before applying it by leaving it for 15 or 20 minutes before spreading it and may give that a go at the next attempt..
It might simply be the low ratio of catalyst, which makes polyester mixing problematic (1.5-2%). I may try doubling or even tripling the amount of catalyst.
One noticeable difference between epoxy and polyvinyl is that the finish on the polyvinyl is much smoother, which may be because it takes such a long time to cure, enabling it to flow for longer..
I'll attempt to finish shaping the shades this weekend.
1 comment:
It sounds like you didn't get the catalyst/resin ratio right or that the temperabut yours shouldn't be?ture was too low for curing.Epoxy is the superior product but you should get a result with polyester...it will be heavier and more flexible doing what you're doing.I did a gelcoat repair (polyester) in an outside barn over the weekend and it wasn't hard enough to sand for 4 days... partly, possibly, due to the component parts being couple of years old
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