Removing paint

Finally I can look and see about re-painting the GPz. Question: what's the best way to remove the old paint? The PO painted it some kind of green but the paint still feels soft. The metal parts can be blasted but what about the sidecovers, fairing and rear cowl? I was told soda blasting would strip the old paint without harming the plastic. True?

Brake fluid will strip paint and not damage the plastic, but I believe there is plastic paint stripper out that works good too.

Be careful with blasting and stripping too. Never take sheet metal to a sandblaster... You will have much less warping and "good metal" removal with a plastic or organic media. The products that are sold for stripping plastic can damage as well, if not done with care. I've had some luck with that bull dog bumper stripper in the past, but it can swell the plastic if not removed asap. I've also had rubber/plastic bumpers blasted by a specialty media blasting shop, and I was still not happy with the "fuzzies" that it lewere behind.

I would do a solvent test on the paint, and if it doesn't lift, knock it down and use a waterborne primer as a barrier coat, being careful not to burn through before color. I rarely strip parts down to bare substrate, unless I'm dealing with a major paint failure(checking, bad prior restoration that is peeling to metal, etc.). An old single stage enamel job may feel kind of soft, but may ot have any recoat lifting problems...

Just my .02... Good luck!

Matt.

Matt, Thanks for your response.
I'm no expert but it seems to me the paint the PO used was defective. The seat sticks to it and it just feels soft. Maybe not enough hardener? It also faded horribly. I think if I tried to sand it it would merely clog the paper. My painter suggested wet sanding it but I don't know what that would do to the plastic underneath. I have paint sticking to my seat so I think it needs to come completely off.

Advice?

If the vinyl just sticks to the paint on the tank without marking it, that screams enamel in my book, and isn't a huge issue.

if it is soft enough to transfer to your seat, do a solvent test to see what you are dealing with. place a lacquer thinner soaked rag on a spot for a minute or so, and if the paint will wipe off, then you are dealing with an under hardened product that may lift on recoat. you may be able to wipe it all off with a solvent if it's too bad, like if it has no hardener in it at all. I've had to do that when one of my preppers edged in a hood and forgot the clear hardner. it took a long time to do, to say the least. :blink:

If thinner doesn't have an effect on it, and if you can't bury your finger nail in it, then you may just want to wet sand it with p320 to avoid clogging a $40 roll of DA paper, prime it with a barrier coat, and rock and roll.

I am not trying to sway you one way or the other. Mainlybecause I havent seen what you are dealing with in person. If you do chemical strip the plastic parts, just follow the product directions, and don't over expose the plastic... it WILL swell and deform if you aren't careful.

Blasting seems a bit extreme to me, but if you decide to do it, take it to a shop that does plastic, walnut, corn cob, and baking soda blasting. If you trust them, let them choose wich one is right for your application.

Matt.

Matt,
Again, thanks for your response. I tried the laquer thinner test and while the paint does not wipe off it does discolor and scratch. I took a couple of pictures so you can get a better idea of what I am dealing with.
This is the tank. You can see where the front of the seat has been sticking to it.

Here is the rear cowl where the seat sticks:


The paint is awful... It was done by the PO so I have no idea what it is. Could be rattle can for all I know. It sure fades fast in the sun.
What do you think?

Have you tried Aircraft Remover (WalMart carries it). Worked great for me. Didn't try it on the plastic parts however. Not sure what the compatibility is with plastic.

As to removing paint from the plastic parts, there are probably better methods with specialized paint remover products; however, some folks report good success by using brake fluid (soaking the part in brake fluid), DOT3 or DOT4 (not DOT5 silicone) as the paint remover.

Perhaps using a plastic bag.

Hopefully, someone who's actually used the brake fluid method will post about their experience with it.

My experience is limited to being real quick about removing spilled brake fluid from painted parts. :pinch:

Good Fortune!

Hmmm. Looks like enamel. It wouldnt take much time with stripper to remove that by the looks of it. Rough it up with 80 grit paper by hand to open it, lay on some stripper, and watch it lift.

The dedicated "bumper stripper" products should work fine for the plastics, just as long as you get it off quickly after it lifts the paint up. Use aircraft remover on the tank first, so you know what to expect.

After the nasty paint is gone, prep it for primer, etch prime the tank metal, use adheasion promoter on the plastic, prime it, sand it, and have a fresh base for your new paint.

Matt.

Thanks everyone. I am going to look for some bumper paint remover. I'll let you know the results
Jim

good luck ! Just remember to follow the directions... if you are unsure of something, this is what my auto body instructor in high school would say:

ask before do, so yourself you don't screw.

Matt.

brake fluid works great. used it on my side pannels and tail section. took about 24 hrs to do the job.