Imperial Home Page -> Repair ->Body -> Paint -> Strippers
Question from Mark:
What are the best methods for removing paint from large body panels. I have been doing it by hand with a sanding block and 220 grit sandpaper, but it is taking forever. I have an air compressor and 2 air sanders, but I am unimpressed with the results of using them. One of them is a really cheap one that my wife bought for really cheap (though even with that she paid too much for the piece of junk), and I have a nicer one, but it requires about 90 psi to operate, and my compressor will only put out about 60-65 PSI at a sustained rate with the volume of air that the sander requires. Needless to say it works ok until the sandpaper touches the car at which time it slows to a stop without having done much.
What do most people use for removing paint?
I use a random orbit sander that has a 6" disk. It is air powered and my compressor will keep up to it at 40 psi. I like to run it with more pressure but it runs fine right down that low. I'd say go and look for a good random orbit sander that your compressor will keep up to. What cfm is your compressor. Mine is 7.7 cfm.
I remove paint/primer from cars almost on a daily basis. The main thing you want to look at when you're removing paint is the end goal of what you wish to accomplish. Even when it comes to removing paint for prep/repair, there are different methods, some of which you do not want to do in certain situations.
The easiest by far is chemical "aircraft" remover. I do not recommend this as it's quite the nasty job. The chemicals are volatile, the chemicals used are harmful to just about everything not man-made, and these chemicals need to be completely neutralized lest they come back and destroy your paint job. If you absolutely have to do this, take it to a professional and let them do the dirty work and let them deal with the EPA.
If you're stripping paint to repair rust, the best that I've found is a 24 grit grinding wheel. I use a CP pneumatic 7" one, though, this can be rather big for confined areas. You can use smaller size wheels found at paint and body stores, Lowe's, Home Depot, and Sears. This is the fastest and most effective way to remove everything in preparation for welding or making a fiberglass patch panel. Unfortunately, after you use this, you'll need to sand it with a DA or file sander and work from 36 grit to 180 grit as 24 grit scratches will show through paint and primer. Another big drawback is that these grinding wheels generate a lot of heat and can warp panels if you let it build up. If it's glowing red, and it's not a weld you're grinding down, you're running it too hot for stripping paint.
If you have surface rust, and wish just to sand it down to bare metal the DA works best. A random orbit is okay, but I have DA and not a random orbit so I use the DA. For this, you want to start off with 60-80 grit and work your way up to 180 grit. Then, block sand it with 220, then primer. Then sand with 400 then 600 to prepare for paint. Most quality DA's are adjustable so you can control the speed of material removal. My IR 'handle-style' DA will strip to bare metal at full blast and 80 grit in under 10 seconds. My hand held Hutchins will do a similar job in about a 30.
If you're in a tight spot, the de-rusting wheels are around 24 grit, and do a fine job if you're cleaning up a seam you wish to weld a panel upon.
Now, this is a little known fact, but there are 2 different kinds of sandpaper. There's "American" and "European" standard paper. This is extremely important! American sandpaper, primarily made by American companies (Norton, 3M) has a number only (80, 180, 220 et al). European paper, specifically Mirka (Finland) has a "P" designation before the number. This "P" actually means that the paper is about 1 grade less than American paper. By grade I mean that if you had 80, P-80 would be roughly 60 grit. I didn't know this till a PPG rep told me about it. Sandpaper is sandpaper, and the better brands are going to be comparable in quality. Auto sandpaper should be wet/dry if purchased in sheets. Self-adhesive paper (purchased for round DA's etc) isn't always wet/dry.
The auto body industry uses orbital air sanders extensively, and they should know. Good advice might come from someone that does this for a living locally.
It sounds like you have not enough compressor to do the job. The speed that you sand depends on the roughness of the material, too. If you have a rough grit, you'll sand faster, but will have to use finer grit later to smooth out the results of harsher grits.
Most all compressors are rated at 125PSI or higher. The 20 gallon tank indicates it is probably about a 2-3 horsepower unit. The issue with air tools is that they need a certain amount of air (CFM) at the specified pressure. For instance, 9 CFM at 125psi. My previous compressor was a 5HP 30 gallon Sanborn unit that I got at Sam's Club. It would do fine on a DA or RA or even jitterbug sander for a few minutes but eventually the pressure would drop, the sander slow down, and I'd have to stop and wait for the compressor to catch up. It's a pain and the compressor ran nearly continually when I was working on the car. Somewhere on your compressor should be a tag stating the HP, cfm etc. If not, and you can find the HP, you can compare it to others of the same HP. Yours will be about the same as others. Ie, all 5 horsepower compressors have about the same capacity.
If the tools you want to use require more air than your compressor can sustain, you are in for an exercise in frustration and a larger compressor might be in order.
I finally gave up and invested in a 6 1/2 HP two stage unit which will run any single tool I have (including a 8" air grinder/polisher) all day long at 125PSI and not run continually. When I try and run two tools at once it will slowly run down but that hasn't been a problem.
Most of the cars I work on already have 2-3 coats of paint. I personally use 36 grit discs on a DA, and gently sand down just until I see scratches to bare metal. It doesn't take long, as 36 grit media is just a little smaller than county road gravel :)
This usually leaves a coat of primer, with some scratches to the bare metal. This knocks the paint off in a hurry. Then I go back with 80 grit and take it down to the almost bare metal, again without really leaning on the sander, just letting the machine and the paper do the work. You can then finish up with a lighter grade (180? 220?) and begin building up. The DA (dual action) moves slow enough not to generate sufficient heat to warp panels on the '60's car (although I wouldn't do it on an '02!). A spinning disc moves the paper at a high speed at the edges... the larger the disc, the higher the speed and the greater likelyhood of making a gouge, hole, or warping the panel.
If you don't have sufficient air pressure to run your DA constantly, you might want to rent a bigger unit for a day... it'll save you days over having to wait for your compressor to catch up!
I would highly recommend http://www.autobodystore.com/. The professionals and hobbyists at this site will answer questions about most anything related to autobody repair.
Question from Johann (1965):
Had my '65 LeBaron at the hobby shop on base for a check-up today. And I took off the "chrysler badge" that sits just behind the front wheel on the passenger side.
It's about the size of a quarter and was painted over by the previous owner in a disgraceful attempt at a paint job. Having only seen one other 65 LeBaron (mine) Id like to know if there is anything under the body paint besides the gold (it's visible on the back side of the badge).
If not, I can use a solvent to remove the body paint and the gold filed metal will remain, correct?
And is there only one badge location for a 65 LeBaron? I couldn't find a hole or at least a patch covering one on the drivers side.
You should be okay just to remove the paint, stay away from abrasives though. As far as the Pentastar "badge", you're only going to find the one...it's a "signature" if I recollect correctly. Our '64 is the same way; I went on a quest to find the "missing" one for the left side until someone educated me.
The Pentastar appeared only on the passenger side of the vehicle in North America, and was used on all Mopar cars, from Valiant to Imperial starting in mid-1963. The medallion is not gold filled by the way, just aluminum with a gold-colored coating.
There were two versions of the 'star', one aluminum and one plastic. From 1963 to 1965 the metal version was used which was part number 2445 182. The plastic version appeared in 1966, and was part number 2785 540, and both versions were used in production in 1966. Not sure about after 1966, though.
Being a metal one, you could try to clean the paint off.
Question from Bob:
One of the restorers I spoke to recommended stripping the body with sodium bicarbonate particles: 'soda blasting'.
Has anyone on the list had any experience with it? I seems very attractive: it is very thorough, it does not damage or alter the metal surface, it washes away, and it apparently leaves a coating that discourages rust.
It seems to be ideal: any downsides?
I've seen articles about this in some of my Street Rod magazines. Doesn't harm chrome, stainless or even glass but somehow removes paint. It takes a HUGE compressor, one of those things built from a V8 engine that they use to run jackhammers.
I read the same thing in a magazine on auto painting. It stated that no matter how careful a job is done, it will never be as good as the factory paint job. It states to remove only where rust or damage needs to be repaired & leave as much of the original as possible.
From Wayne D:
YES, stay as far away from that stuff as possible. A friend nearly RUINED his car with it. First, it does not leave a rust proof coating on the car, quite the contrary, my friend was told to wash the car in vinegar to neutralize the baking soda, and immediately a fine coat of rust appeared. Second, the stuff got into all the nooks and crannies imaginable including under the dash, etc. When he took the car to a first rate professional, the car had to be restripped to be painted correctly. My question to anyone considering stripping is "why?" Unless the paint is badly damaged it can be sanded, either by hand or with a machine, and under that paint job are all sorts of primers and rust proofing, why remove it?
From Wayne J:
I had the paint removed from my 1966 Convertible with this (soda blasting) method, and I have been very pleased with the results.
Why strip off old paint?
One of the most important components in a good paint job is proper surface preparation. My car had been previously painted with a cheapy paint job. This 2nd paint job had adhesion problems. The only way to get a satisfactory paint job was to totally take it down to bare metal. In my opinion, if a car already has had one repaint, the car will need to be stripped by some method, before it is repainted again. Without stripping, the paint will probably crack, no matter how nice it looks initially.
The soda blasting was done by my body shop - who then did the rest of the body work and then did the paint work. Soda blasting - in my opinion - is the least destructive method of removing paint. Sand blasting can warp metal, if one isn't careful.
The soda blasting took the paint off - but left the factory filler in place.
The baking soda does get in every nook and cranny - but so does plastic media blasting. Since this was a total repaint - as well as rust repair - I had completely removed the interior - so this was somewhat less of a problem.
When I get my 71 repainted, I will use the same shop, and also have it soda blasted.
I just want to chime in here and agree with Wayne's assessment. When I went to body work school many moons ago, my instructors said never remove the original factory primer unless you absolutely have to. Why expose metal to the air, that hasn't been exposed since before leaving the factory? Unless I was restoring a shell that already was coated with surface rust, I wouldn't strip it, except in small areas. Also, if you have a vehicle with several extremely thick coats of paint, you'd be surprised how much you can remove with a razor blade scraper! Just don't dig the corners into the panels, creating long scratches to sand out. I expect to use a scraper to remove the highway department yellow on my roadrunner, as well as the thick, but still shiny, park department green on my 68 Imp coupe, then save the sanding for finish work. While it works for some, I've seen more cars messed up by improper stripping, then I have seen stripped cars that the paint job lasted for any length of time.
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