Stripping the paint off my S4

PostPost by: djb222 » Sat Mar 02, 2019 6:58 pm

This week I finally started to remove the paint from my Elan. I've decided on the most time consuming method, but, in my view the least messy!! I know I'll reach a stage where I'll have to resort to grinding out faults....but that's for later.

I was little surprised as to what I found under the paint on the front of the car, smears just a thin layer of primer, but then other areas a fairly thick layer of some sort of 'flexible filler'!!! not sure what this is...any ideas..

The section behind the bumper has a very hard layer which does not look like filler, and has some stress cracks...again any ideas.

I'm planning on doing as much of the prep work as I can, I've prep'd and painted a few cars in my younger years bur never a GRP body.

Here's a video of the start of the process.

https://youtu.be/SlQWuEvwQNA
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PostPost by: nmauduit » Mon Mar 04, 2019 12:21 pm

I also only use dry mechanical means for taking the paint off, to reduce as much as possible the risk of encapsulating contaminants. Then you still may want to consider a good sealer, preferably from within the paint system you will select to be on the safe side. Looks like you're starting with a body that does not have many layers on, which is promising.

I believe the somewhat sticky blue-greyish stuff at the bottom was factory, I found it on two S4 FHCs that had never been stripped - could have been the equivalent of build epoxy primer of the time..
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PostPost by: denicholls2 » Wed Mar 06, 2019 12:36 am

The stuff under the bumpers looks to me like gray gelcoat. As the car has clearly been stripped in its lifetime, this might have been missed or skipped because it is under the bumpers and was the original gelcoat. The car looks to have been driven by ear a lot, hence plenty of repair.

The greenish filler under the place you stripped in the video looks to be a polyester filler like Bondo or White Lightning but a different brand, popular in period on this side of the pond. It was used much like high-build primer is today as the final surfacer. I expect you will find uneven repair under this area as I doubt it is original.

I don't know that I'd worry much about the filled pinholes, they look stable and as you're planning on a veil layer, it'll all get covered. Digging the stuff out just creates more work, though it is true there are better ways to fill pinholes.

You might want to try my method of stripping, which is 2-4 times as fast as yours and won't gouge the fiberglass (or at least not as much, and doesn't require frequent sharpening. The knife will be bin-ready when done, but it'll likely only take one knife for a whole Elan, the blade will flatten into greater contact as you go):

    Procure a CHEAP 10" slicing knife. Must be cheap and have a flexible blade, that being able to, with a fair amount of force while holding the handle, bend the point 2" from straight and have it return to where it was when released. Best not taken from the wife's kitchen drawer unless you first replace with something she likes better. :)

    Holding the knife by the handle, apply the blade to an area needing stripping. Blade is vertical to the paint.

    Grab the blade between finger and thumb near the point and flex the blade back and forth over the paint. the blade will contact where the point finishes its curve and flattens out into the blade; the motion will create the same scraping effect you're getting but your method applies a gouging force -- more damaging and less effective. This method flexes the paint just enough to detach it from the substrate. Depending upon the bonding of layers, big chunks will come off when the angle is right.
Rather than using your scraper on the green filler, I would recommend sandpaper. Faster and leads to a better surface -- this stuff is not nearly as hard as paint. 110 grit might not be aggressive enough for this stage, try 60. The discrete abrasive pieces will slice through to the fiberglass/polyester resin, but likely not have much of an impact on it. (That's very hard stuff even after fifty years.)

It must feel good to have committed and made progress. Better than fretting about what may happen when you do.
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