Factory paint for "rubber" bumpers?

[G B.]

I'd appreciate a short course from someone in factory painting procedure for the late seventies Corvettes with "rubber" bumpers.

I really don't remember anything about the factory paint process in the late seventies, although I went through the St. Louis plant several times during that period. Were the plastic bumper covers on or even with the body when it went through the lacquer spray booth? Were the plastic covers painted with the same lacquer and primer system that was used on the fiberglass body? Were the bumper covers subjected to the high heat of the reflow step?

[Walt McGaw]

Re: Factory paint for "rubber" bumpers?

Hello Jerry,

My response is not based on fact for the plant, but I was doing autobody repair back during that time, so this is my theory.

The bumpers needed an additive in the paint they received since the bumpers were a soft pliable material compared to the fiberglass. This additive made the paint more flexible so that it would not easily crack when the bumber flexed. I would think they would have been painted off the car with a different paint mixture and then installed after drying.

Walt

[Tom B.]

Re: Factory paint for "rubber" bumpers?

The one new "Primer" '77 Corvette that came in the dealer where I was working was equiped with silver painted bumpers. Obviously not painted on the car. the flex agent required for the bumper covers has often been blamed for the mismatch of color between the car and bumpers on these years.

Tom

[Greg A.]

Re: Factory paint for "rubber" bumpers?

Jerry, from what I've read about the St. Louis plant, these rubber bumpers were painted in a separate part of the plant and not done at the same time as the car. Probably for the reasons stated by others that it was a separate paint because of the flex agent. I've seen pictures of the T-tops going through the paint booth with the cars, but never the bumpers.

Greg.

[John H.]

Re: Factory paint for "rubber" bumpers?

The RIM (Reinforced Injection-Molded) Urethane bumper covers were painted in body colors by the supplier (Guide Lamp Division, as I recall), and were received at St. Louis ready to install. Guide used a special low-temperature flex-agent paint formulation and buffed them after low-temperature bake to get the required gloss level. A local dealership Body/Paint Shop or automotive paint supply store should be able to tell you what they add as a flex agent when they paint replacement front and rear bumper fascias.

[Bill W.]

Re: Factory paint for "rubber" bumpers?

We used a flex agent in the 70s that made the paint dry slower it never seemed to dry or get hard . and didnt buff well at all. The reason the factory bumpers were always dull was because the paint was an acrylic . Acrylic is air dry or dries by oxidition . the problem was the additive never dried so the paint never stopped oxidizing. once all the good solvents were dried out all that was left was colored chalk..The new flex agents that you can use today dont affect the color but still never get as hard .Bill