"Dodd, Kelvin" wrote:
>
> > I have a similar question relating to my "new" BMH MGB Body
> > Shell which
> > is still in it's crate and has been waiting for me in the
> > garage since 1991.
> >
> > My understanding was that these new body shells were dipped in modern
> > primers during manufacturing. On close inspection it appears
> > there are
> > two primers on this shell. A darker gray which appears to be
> > "thinner"
> > and can only been seen inside the shell members, where it was hard to
> > reach with spray, and an outer lighter gray, and thicker,
> > primer which
> > appears to have been sprayed over the darker coat.
> >
> > I have two questions:
> >
> > 1. Can these two primers be used as a base coat after proper
> > sanding and
> > surface prep?
>
> To my knowledge. Yes. When they were building up complete cars,
> they never stripped all the paint off.
>
> >
> > 2. What if anything was done to the inner sills during manufacturing?
> > After or before welding were these protected in any way?
> > Would the dip
> > primer reach them, or are they unprotected and have been rusting away
> > while sitting in the crate these 12 years?
>
> This is a very good question. Kai pointed out that he knew of a BMH
> shell rebuild that started to rust after only a few years. This indicates
> that the rust proofing is not dependable.
>
> I would strongly suggest going in after the car is painted and
> protecting the interior of the rockers with a spray on coating. You could
> do this now, but you have to make very sure all the goo gets out before you
> spray the car. Better to spray the car first, then goo.
>
> I think you will find the thin primer is from the dip tank. Then
> when the outer body panels were assembled, the assembly roughness and
> transport dings were filled, then the whole body shell coated in primer
> surfacer. At this point the shell should really be sanded down by someone
> that knows what they are doing, so any metal-primer problems get sorted out.
> This does not mean going down all the way to metal, but down far enough so
> the new etch prime coat can adhere well.
>
> I would strongly suggest taking this up with a good body man who
> knows their materials. That is the only way to get a reliable answer.
When I reshelled the Cooper S, the body came with the black stuff on it.
My paint shop had the shell dipped in a rust-proofer, then sprayed epoxy
primer/sealer and baked it, then sprayed and baked again. Then the
colour coats were applied (yellow first, then mask and spray red) and
baked in the oven again. I applied no wax for six months, but kept it
clean, applied the decals and vinyl stickers and then buffed it and had
a semi-flexible clearcoat applied.
The colour coats had had a little too much hardener mixed in, so it has
taken a few stone chips in the four years it has been on the road. None
of them went to the metal, only to the epoxy layer, and there is no rust
on the car anywhere.
I recently had damage to the boot lid, so I bought a new one and had it
painted by a different shop (the old one had closed), so I have a small
can of colour-matched red I will be using to redo the stone-chipped
spots.
I think the rust inhibitor and baked epoxy undercoat is the way to go.
-Rock http://www.rocky-frisco.com
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