C2 original formula panel bonding adhesive

[Ronald L.]

I asked this question 9 years ago, never got an answer, yet I though for sure over the years, at one of the Nationals John H had shown us what this was.

Question - repeated what was the original boding material composition?

Was it 1/8" fine chop glass, resin, and hardner?

If that is what it was, how did it get dark gray?

[Mark E.]

Re: C2 original formula panel bonding adhesive

I don't know what they used exactly. But it was some form bonding adhesive, not fiberglass matting ("chop glass").

When I learned fiberglass body repair in the mid-70s, bonding adhesive was available in a few "colors" depending on brand, including grey.

[Cecil L.]

Re: C2 original formula panel bonding adhesive

I seem to recall resin with thixatrope added for thickening. Thixatrope was a gray powder, probably ground fiberglass,. I think I have a can of it from the 70's.

[Mark M.]

Re: C2 original formula panel bonding adhesive

Maybe someone with knowledge from GM could chime in but my experience and that of a friend and corvette restorer for 40+ years, have used RENPASTE 1250. Sold years ago through GM dealers for corvette panel replacement but now through other sources. There's numerous pictures of GM line workers applying the adhesive with pastry type paper cone squeeze applicators laying down dark bonding adhesive. Ren 1250 is an aluminum filled resin. When you grind original bonding adhesive the aluminum can be seen. GM must have intended RENPASTE 1250 as the designed material for repairs. I've tried a number of aftermarket adhesives that all seem to work well but REN is most similar to original. I applied REN with a cone fabric bag once and it seemed to thick so just a putty knife laying a bead that squeezes out with panel install just like original is all that's needed. I don't know how GM line workers mixed batches of adhesive but when REN is mixed by hand the paste gets softer the more you kneed it so maybe thats how they got it through the cones. REN 1250 comes in a quart of resin and a quart of hardener. One is gray and the hardener is black which looks most like the original adhesive. I don't know why the original material was dark at times and the color was pink some times. There may have been variances in coloring from the suppliers back then. Anyway there's my two cents , hope it helps someone.