Underside coatings

Along with Ron's subject of sound insulation,
how about underside coating for the fiberglass
to resist chips and scratches from road debris
being kicked up?

ERA has an option for some sort of asphalt
material.

Ian

Ian,
Most guys I know are using that Rhino-liner for pickup beds. The Cobra guys use it under their fenders and I saw a couple cars like that. It looked good. They can spray this stuff on up to 1/8th inch thick.

Hersh

The story from my local "experts" is that an asphalt / bitumen finish is not good on fibreglass - it stays "wet" & does allow moisture to get in. This was proven to me when I restored my '71 Corvette - when I stripped the bitumen paint off underneath, the surface of the glass was soft & "feathery" with loose glass fibres. I ended up having to sand the lot back to solid glass & then re-lay 4 layers of chopped strand mat under all the fenders (& then sand the damn things back smooth !). The other problem with the soft bitumen paints is that once dirt gets ingrained into it, it is impossible to clean it off - it always looks dirty.

There are two other ways that I have used for underbody finish that I have found successful :

- Prime the glass/steel with a normal 2-pack primer/undercoat, spray on a good layer of "StoneGuard" (gives an orange-peel effect, as seen on the sills of many new cars), then finish with a gloss 2-pack (with plasticiser added).

- Use POR-15 Clear as a base coat for the glass & POR-15 Black for steel/alloy, recoat with POR BlackCote over glass & steel/alloy.

It is worth a look at the POR web-site - they have a range of great products apart from POR-15 & BlackCote. I have used their "Glisten" 2-pack on alloy & polished steel parts - the finish is superb & almost indestructible (you can lay into a piece of alloy, finished with Glisten, with a hammer & all than you get is some dents - the Glisten will not chip or peel).
http://www.por15store.com/information.html

Peter, This Glisten may be what I have been looking for. I have tried the Eastwood's Diamond Clear coating and was not satisfied. The problem was when I cleaned a mirror polished aluminum piece with acetone prior to coating, it revealed superfine scratches which did not disappear under the coating. Along with the distortion of the finish itself, what had been highly polished looked very dull. I had resigned myself to polishing it with Weenol regularly, but maybe the POR-15 Glisten is worth a try? Any comments? (I did try an Eastwoods tech consultant's suggestion of cleaning with Dawn detergent and then rinsing well; this allowed the material to bond well, but it still left a dull finish and was not "self leveling" at all.)

Hi Lynn, I think that Glisten would be worth a try - the POR guys have a metal prep solution called AP120 specially designed for alloys. I have used this on highly polished alloy (just brush it on, leave it for 2 mins & then hose off). It doesn't dull the surface like many other metal prep products. The Glisten itself if truely self-leveling - after trying a few bits with a brush application, I have stayed with it ever since. Two light/medium thickness coats seem to fill all scratches & the final finish is dead smooth. Whats more, the pot life of the stuff is amazing for a 2-pack product - up to 3 days in a sealed jar (and yet, when painted on, it is touch-dry in an hour or so !).

I was thinking of using Rino-liner. It sure looks water tight in pickup beds. What I did on my Cobra worked very well and was easy. I just used spray cans of paintable under coating. The car was shown a lot and after a while the under coating looked dirty. One of my Street rod friends showed me what the street rodders on the show circut do. They go to the Home Depot and buy a gallon of latex exterior house paint and have it mixed as black as possible and then just paint over the under coating with a paint brush. It made the under coating look as though it was brand new again. I never had any problems with adhesion or any other problems.