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I Love Power washers but - sanding question

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JPSmit

JPSmit

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I just finished power washing my midget (76) prior to beginning sanding. As I washed, the paint peeled off over areas that seemed to be undercoated somehow. (Inside fenders/ joints in cockpit and around the engine bay.) All these areas were rough to the feel anyway. In fact, in the cockpit these areas had "browned" either through the paint or on top of the paint.

here's my questions.
1. Is it undercoat?
2. How do I deal with it? I'm not doing a concours restoration by any stretch of the imagination. If this roughness is important and original, I don't mind keeping it but, how do I prep it? Sanding will knock it down. Wire brush? Leave it alone? and
3. Will the new paint (done by a painter not me) adhere?

Help
Thanks
JP
 
It is (was) undercoating and/or sound deadening sheets in it has tiny holes in it.
Basically tar in one form or another.
Use a propane torch or heat gun to soften the stuff then scrape it off. It peels up nice when warm.
A little thinners on any residue should wipe up what you can't scrape off.
Or use a good sealer/primer over the tar before paint.
 
Are you sure it's undercoating and not seam sealer? The inside floors of many LBCs are "undercoated" with sound deadening bitumen goo but if the coating is localized around seams between panels it's likely to be seam sealer which would also be lumpy or have brush strokes.

While doing restoration work it's nice to remove either undercoating or seam sealer to see what's hiding behind it. As mentioned above, heat works wonders. I use a hot air gun and plastic putty knives followed by ScotchBrite dipped in mineral spirits.

Replacing undercoating is up to you. Seam sealer must be replaced.
 
It's probably both. Some was under the fenders - likely undercoating. The rest is seam sealer. I can easily remove it but I presume I'm just asking for trouble if I try to get it out of the seams themselves? (assuming they overlap) Or, would it just make sense to paint over it as almost none of it will be visable anyway?
 
[ QUOTE ]
Or, would it just make sense to paint over it as almost none of it will be visable anyway?

[/ QUOTE ]

A $64,000 question. Undercoating applied at the factory or soon thereafter is probably safe, but if it was applied after the car accumulated road grime and dirty it just glued that to the car and may have created a rust problem.

Seam sealer is rather easier for it was applied at the factory intended to keep moisture out of the seams. The only question is whether it did its job well and/or remains intact.

Its safest to heat it up (carefully since too much heat even from a heat gun might warp a panel), scrape as much off as possible, and then use chemical paint stripper to finish the job. You could even use the chemical paint stripper to start with to help soften it up- but the result is a truly toxic mess and vile beyond belief when heat is applied.

If you need help... ask your worst enemy. /ubbthreads/images/graemlins/wink.gif

Since you say paint has peeled from it- was the car re-sprayed, if so that might be an explanation for such areas may not be cleaned very well and the paint has less adhesion
 
the car has never been resprayed and the panels are in very good condition. There is no hidden rust/ grime in the seams at least. The Sealer is actually coming off pretty good though I'm reluctant to clean out the seams since they seem to be holding. does it make sense to remove up to the seams themselves (ie. the "overspray" that generously seems to have been put on.)
 
Were it me... I'd remove all the old seam sealer and undercoating. If there is no rust, I doubt I'd pick the old seam sealer out of the gaps unless it was loose. Once down to bare metal I'd go through the normal prep steps and brush on new seam sealer prior to applying primer and your top coat. But that's just me. I'm sure others will have different opinions.
 
will the primer hold over the sealer?
 
As long as you use an automotive type seam sealer painting should not be a problem. The problem arises when you use a silicone based sealer which won't take paint. The auto body supply house should be able to help you with a sealer/primer/top coat that is compatible. You don't need to go with one manufacture's system per say, but you should make sure the solvent bases are compatible and that the top coat is something that the person doing the shooting is comfortable with.
 
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