Tank/sidecover prep for paint question

[RastaraL39]

Hey all. Quick question. Have an 81 GS850L with factory paint on tank and sidecovers. I have rattlecan duplicolor black metallic that I want to use for base and then use a urethane 2 part from a rattle can to finish clear. My question is i remember reading somewhere that it was essential to strip all the old paint off as the first step. Is this the right/only way or can i just sand and prime over the old factory paint? Any thoughts/recommendations?

[veg]

you heard correct, its always best to strip the old paint if you are doing a re-spray. Different types of paint don't always agree with each other and its possible that the solvents in a lacquer system could attack the old factory paint.

I'm also not sure how 2k clear will sit over that dupliclor lacquer either, ive never used anything from duplicolor before but the general rule is acrylic lacquer can go over 2k, but not the other way around. It will be ok for a year or so, but the 2k may crack as the acrylic is softer than the 2k. There are produdcts that create a "barrier" between old acrylic and a new 2k system (which i have no experience with) but in your case thats useless as you want to use the two types in the one finish. All of the projects i have had over the years have been stripped completely of the old factory (or P.O's) paint job and shot with 2k from the metal/plastic up. If you do decide to strip the old paint, make sure you use an etch primer first for any metal, and a plastic adhesion primer for any plastic bits.

[RastaraL39]

Thanks. I will go the stripper route and build up from there, that way there are no chances taken. Appreciate the good info.

[SVSooke]

DO NOT use paint stripper on plastic.That is a disaster waiting to happem.Sorry but you have to SAND off the old paint.Stripper will work on the tank though.

[keman]

I used 2K Over Duplicolor laquer on mine. Turned out well. I did not strip my parts, but did use an etching primer on everything.

you can check my photo album to see some of my Pics.

Here's a small one

http://www.thegsresources.com/_forum/picture.php?pictureid=9105&albumid=1705&dl=1318756939&thumb=1

[terrylee]

I used 2k clear over the top of Rustoleum and not problems for over a year. terrylee

[nvr2old]

Agree with NOT using stripper on plastic parts. It'll ruin them. If there's no damage to the original paint, it makes a great base for new paint. Just sand it smooth and repaint. Also (with all due respect to an earlier post)..lacquer cannot be sprayed over urethane..the other way around, sure. Lacquer is one of the hardest most brittle paints known to man..that's why it cracks and checks over time. It's not nearly as flexible as urethanes. To be on the totally safe side you could sand all the original paint off, hit it with a few coats of primer and repaint. Up to you.

[mrbill5491]

I'm looking into using Duponts Imron series paint.

[RastaraL39]

Thanks everyone. I will get going on it this weekend. Appreciate the advice.

[veg]

Agree with NOT using stripper on plastic parts. It'll ruin them. If there's no damage to the original paint, it makes a great base for new paint. Just sand it smooth and repaint. Also (with all due respect to an earlier post)..lacquer cannot be sprayed over urethane..the other way around, sure. Lacquer is one of the hardest most brittle paints known to man..that's why it cracks and checks over time. It's not nearly as flexible as urethanes. To be on the totally safe side you could sand all the original paint off, hit it with a few coats of primer and repaint. Up to you.

I find it surprising to hear someone say lacquer (we are talking acrylic lacquer aren't we?) Is hard and brittle. I was always taught during my apprenticeship as an automotive refinisher that acrylic lacquer is too soft to spray over the top of. Acrylic is so soft, in fact, it never stops shrinking and expanding due to changes in temperature and it is this movement that will cause the paint to "crack" and its also this movement that might ruin a 2k job over the top. The way my boss explained it was to think of an m&m left in a hot car, the hard shell might still be intact, but touch it and the soft chocolate underneath can no longer support the shell and the shell cracks. That's my 2c anyway.

[nvr2old]

Urethane is indeed a very flexible product. It's basically like spraying liquid plastic and is closest to the M&M metaphor you mentioned. Lacquer (acrylic even) is the product that was used almost exclusively for decades in the auto industry, through the 70's anyway. It needed to be polished to bring the shine up before the advent of acrylic enamel, which then paved the way for products like Imron and then the modern catalyzed products that are used today..all products that if sprayed cleanly didn't really require sanding and polishing..plus it always remains a little "cushiony", resisting rock chips better. Lacquer, when it's dry, is rock hard, but brittle. It rock chips easily. If it's applied too thick, in time you can flake it back like shale. Acrylic lacquer is hardly even in use these days outside of spray cans. It's seriously expensive, and a lot of places have outlawed it's use because of the ingredients used to make it. There will come a day when all petroleum-based products might be outlawed. Water base is the future.

[veg]

Hmmm, perhaps I'm thinking too much about industrial 2k (iso, needs an oven to cure) and less about commercially available 2k, which obviously doesn't need an oven to cure, but I have never used a urethane system that hasn't needed an oven to cure so I'll stop talking now.

[RastaraL39]

primed with rustoleum after stripping to bare metal. 3 coats of duplicolor metalflake black. Followed with spraymax 2K 3 coats, let dry 3 days then wetsanded with 1500 then 2000, then used Meguiars M105 with DA polisher followed with M205 [used foam pads on DA]. Came out with nice deep glossy shine.

[mrbill5491]

Going with the Dupont Chroma paint, Imron is too hard of a paint and cracks on plastic parts. Now I just gotta figure what color of orange to go with...