How to strip the body in those awkward places

[buzzer]

Guys
I'm stripped most of my europa body of all it's paint in  and repaired where necessary. I mechanically stripped it with a sander. Ground out the crazed gel coat, repaired and tissues up, filled and then hand finished.  Still a lot to do but my main challenge now is stripping the paint from body shut profiles on the boot and bonnet (or hood) for you lot over the pond. This is proving tricky to do it mechanically with drills and dremel and hand. Has anyone got any good ideas how best to strip the paint.  You can see the area on the pic what's have to do

[EuropaTC]

As you say, those parts are a real PITA. Although it probably goes against the usual advice I used paint stripper to soften it and then stripped it off with 2 old (read sacrificial    ) wood chisels, 6mm & 12mm widths I'd guess. 

If you're careful then you shouldn't go through the gel coat as the paint will be soft from the stripper.  That will of course leave a few scratches to be sorted out where you inevitably slip and cut too deeply, which I clear with 80grit production paper.  I don't bother filling or going to wet and dry in those areas, just spray with polyester filler (UPol Reface as you're in the UK) and dry sand that until it looks reasonable.

Brian

[buzzer]

Brian,
I came to that conclusion that would use paint stripper on those areas.  The guy that will stray the car for me told me about the polyester filler that can be sprayed on.  What paint stripper did you use?

Dave

[EuropaTC]

Hi Dave,

If I'm honest I use whatever the nearest DIY place has in stock 

I tend to go for the thixotropic versions.  I don't like the thin, watery strippers such as Nitromors used to be as I found it just ran off vertical panels without doing the job, so I go for something thick and stodgy. The last ones I used were Wickes own brand, which is a white stripper about the thickness of custard and I thought was quite a slow reaction.  I would often paint it on very thickly at the end of a day session and by the next morning the paint would be just right for stripping off.  Of course that depends to some extent on the old paint type and how many layers you need to remove.

I have also used thixotropic methylene chloride strippers (Polycell) which are much faster acting - say 30-60 minutes to completely soften several layers.   The downside is that if you're not careful you will damage the gel coat with a chemical attack, so I would only use that for stripping outer layers and never apply it when you get to the base primer levels.  If you try these strippers then I would urge caution and test small areas until you're confident on how quickly it reacts.

IIRC the Wickes one was caustic based which will also go for the gel coat if you try hard enough, but it's far easier to control.

Brian

[buzzer]

Brian,
Thanks for the advice. I am avoiding the ones that attack the gel coat and trying on a small area. Part of my issue is I have crazing so the concern is that paint stripper will get into the fibreglass, however as this will be cleaned off and tissued up I shouldn't get any substrate issues. I'll keep you posted how I get on.

Dave

[EuropaTC]

Hi Dave,

Unless you have glass fibers from the matting showing through and no resin coat left at all, you will be fine.   If we're talking of the usual crazing then it'll be safe to use paint stripper providing you go about it sensibly, which of course you are doing.   If it's any help, I've done exactly the same things on crazing without problem. The resin is fairly resistant;  if there are large amounts of filler then that can react badly, but of course you'd want to get rid of filler anyway.... 

As a bit more encouragement, back in the day when people paid me to attend work (rather than paying me a pension to stay away    ) we had several GRP storages on site. Some of these were old and had crazing similar to what we see on our cars and yes, if the crazing was internal then we would find structural deterioration in those areas. 

But the key thing is that they were exposed to chemicals 24/7 and normally for continuous periods of two or more years.  So the time for attack was massively more than you get from what you're doing.  If you use something like a methylene chloride stripper which is known to be aggressive towards polyesters then you have to be careful, but even so it's hours rather than minutes for any significant damage.  If you did use chemicals as aggressive as MC then you'd get the message very quickly once you saw the paint lifting itself off the car !   

Brian

[Chuck Nukem]

I am planning to use something like this for those tight spots. Only a theory.

http://www.harborfreight.com/power-tools/sanders/1-2-half-inch-bandfile-belt-sander-92158.html#.UxCaO4W2wRI

[buzzer]

I looked at those narrow belt sanders, was in 2 minds as to how well it would work. The main thing is can you get it into the tight spaces well enough. I didn't get round to measuring it though. If you use one post how well you get on with it, be definitely interested.

Dave

[Chuck Nukem]

I will let you know. Hopefully my hours of body work are fast approaching. 

[3929R]

For tight spots on other projects I prefer an oscillating tool such as this- http://www.harborfreight.com/power-tools/oscillating-tools/variable-speed-multifunction-power-tool-67537.html#.UxDNv_ldV8E  The pads and blades can be trimmed/ground to various sizes and shapes.

For chemical striping I use putty knives that I grind to the profile of the piece I'm working on (which is usually wood).  I also use my grinder to ease the corners of the putty knife so as to reduce scratching/gouging.  And I bend the blades as needed to get a better angle to push/pull across what ever surface I'm stripping.  Putty knives are cheap enough to grind one to the needed profile for a specific job and then toss it when done.
http://www.harborfreight.com/catalogsearch/result?q=putty+knife

As a side thought, does a heat gun have any effect on automotive paint?  Or will the fiberglass melt before the paint softens?  Just thinking out loud....

[EuropaTC]

Hey Mark, that's a good tip about grinding putty knives. I'd never have thought of that and it would be ideal for some of the recesses like the rear tray shut areas.  Thanks for posting.

Brian

ps Following the "thinking aloud" theme - I've not used a heat gun on grp. I don't know what temperature cellulose paint softens at, I'd have guessed over the 100C mark ?

What I do know is that when designing grp structures we tended to assume softening points for the resins at around 120-130C (depends on the resin of course). That wasn't the "I'm going to fall apart" point, but simply where properties started to fall off. I don't think you'd melt or degrade the gel coat before the paint went, but I'd be concerned about locally high temperature gradients and the stresses that might impart. It'd be a real PITA to strip the paint and then find the surface all rippled.  Any trail blazers out there ? 

[buzzer]

Well guys I did try a heat gun on the celulose paint just on one point. It softens but not early to remove as it cools very quickly and bonds well to the primer.
there is a video on you tube of how to strip polyester (I think) paint off fibreglass with a heat gun and then just rolls off
I took a pic of my effort with the heat gun,  not pretty!!
Dave

[EuropaTC]

A trail blazer - well done that man !

Was the youtube video the one about the corvette ? I found that one and wow, that paint just falls off. The title said "Acrylic" so it sounds different from the stuff Lotus used, but it was fascinating to watch. 

Either the guy has asbestos fingers or it couldn't have been that hot because he wasn't wearing gloves and kept testing the panel temperature with his hand.  I'd guess it was softening at what - 60,70C ?  I don't know much about acrylics, anyone used it or do we have an expert on here ? 

Brian