View Single Post
Old 02-02-2013, 05:09 PM   #1 (permalink)
turbothrush
EcoModding Apprentice
 
turbothrush's Avatar
 
Join Date: Nov 2008
Location: Canada
Posts: 133

2 x wrecked vx - '92 Honda Civic Vx
Team Honda
90 day: 62 mpg (US)
Thanks: 119
Thanked 54 Times in 30 Posts
Improve the bond - Fiberglass/Epoxy to Home Depot foam (extruded polystryene)

I did some testing on adhesion last winter and found rough sanding the foam was not the best solution for adhesion at least not with the materials that I used. Sanding may work fine on urathane foam, I don't know.

I should also say the test was only a peel test and I used the exact materials that I was using on my build. Foamular C-300 from Home Depot / U.S. Composites 3 to 1 thin epoxy 635 / 6 oz e glass fiberglass. I tested various grits of sandpaper from 220 down to 20 grit (had to glue the 20 grit to a block of wood and kind of twist it into the foam) as well as drilled holes and holes poked with a scratch awl also with and without 3m super 77 spray glue.

The only sample I saved was the one I found to give excellent results which was scoring the foam not rough sanding. I scored the surface of the foam with a stainless steel pet brush from the dollar store. This only seems to work well if you score lenghwise and what you are looking for is score lines like in the pic . If you use a plastic squeege to spead the epoxy it seems to "key" into the foam quite nicely and gives a really strong bond. So strong you can rip the cured skin of fiberglass (6oz.) before it will detach from the foam.

If you don't have a dog or cat then a gang of utility knife blades with some thin wood spacers between them works at least as well as the brush.

I realize that there is lots of other methods as well, like holes drilled or cut and wood dowels or blocks of wood inserted to join the two skins but the scoring method is nice if you have a large area to do like I did.
Just thought this might be of interest to someone since this bond is so critical to success.
Click image for larger version

Name:	photo (6).JPG
Views:	968
Size:	56.1 KB
ID:	12402

Click image for larger version

Name:	photo (7).JPG
Views:	760
Size:	54.3 KB
ID:	12403

Click image for larger version

Name:	photo (4).JPG
Views:	2320
Size:	139.3 KB
ID:	12404


Last edited by turbothrush; 02-09-2013 at 02:24 PM..
  Reply With Quote
The Following 6 Users Say Thank You to turbothrush For This Useful Post:
3-Wheeler (03-12-2013), a8ksh4 (03-31-2013), Christ (03-11-2013), nateshuntsvegas (03-11-2013), NeilBlanchard (02-03-2013), skyking (03-18-2013)