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Epoxy onto polyester?
dhutch - 26/4/10 at 11:18 PM

Can i use epoxy resin to repair/modify some body work (boot box) thats been made with polyester resin?

Doesnt have to look pretty, but ive bought a seoncd boot box to hack about around the rollbar struts and have about 2kg of out of date epoxy to use up.

Daniel

orton1966 - 27/4/10 at 05:22 AM

The simple answer is yes, as a general rule of thumb you can always use a better resin to repair something made from an inferior resin so:

Polyester can be repaired with polyester, vinylester or Epoxy
Vinylester can be repaired with vinylester (polyester also if careful) and epoxy
Epoxy can only easily be repaired with Epoxy

And that’s the rub, once you’ve modified or repaired something with epoxy you’re locked into using it for future work. Depending what you’re doing epoxy also has other issues for example, it doesn’t work with chopped strand mat so you have to use cloth based reinforcements. Whilst cloths are lighter for a given strength you need more layers to create rigidity and they don’t drape or go over irregularities easily. Finally you need to be more selective about paints, especially primers to get good adhesion to an epoxy surface.

Not trying to put you off but you do need to think ahead to what else you might need to do with the panel

dhutch - 27/4/10 at 08:52 AM

quote:
Originally posted by orton1966The simple answer is yes.

[but] once you’ve modified or repaired something with epoxy you’re locked into using it for future work.

Ok thats interesting.

I dont know what i would paint it with, the epoxy can just be painted with a half decent one (or two) pot polyurethane but that might not stick to the existing polester?
- My plan was to leave most of it self coloured (which is yellow, the same colour as the car) and just paint the modified section, which will be most of the two ends, with a colour to roughly match.

On the flip side then i guess, does anyone do a nice polyester kit with kilo or so of resin?



But certainly i need to think about exactly what its going to look like.
The bars are fairly incrouching on both sides and not parallel so my thought was to basicaly cut a slot down the side and into the floor as far as needed, then to glass round upto just under the high of the box edge and back to the end. The box would then have to come out with/after the roll bar but they would separate and wouldnt have to resined up together.




Daniel