Paint Systems: A tempest in a Teapot

[ga_mtn_spider]

I like spraying bc/cc or basecoat clearcoat but let me explain if you paint your car with single stage and it is wrecked most likely the repair facility will refinish the repair with bc/cc. unless the color match is dead on they will prep for a blend into the next panel which will consist of scuff or sand then papering it off until the new or repaired panel is sufficiently base coated, once it is they paper is pulled off the blend panel allowing the base to be dusted into the blend panel, just enough to give the appearance of a perfect color match. Then the deal is sealed with clearcoat the entire panels with clear. If the repair shop refinished with single stage it can be blended but I don't consider it to be a repair to last as long as the rest of the paint. You overthin your last coat just where you are stopping the paint, I personally put hot reducer in the gun and flash a quick coat on the blend to melt it in. You can then bluff and it look great but many time it will develop a hazy streak over time. Back in the mid 80's PPG come out with Deltron and sent me to The Ford plant in Hapeville for a 2 day school. According to PPG the basecoat clearcoat set up came about to make it easier to apply metallic and pearl colors. I will tell any of you if you are thinking of painting anything with metallic in the paint and have no or limited experience go with bc/cc it makes it a lot more goof proof and if you have a problem you can correct it quickly in the basecoat. Single stage has the nasty habit of the metallic moving around in paints that sit and stay wet,that's what gives the cloudy or modeled appearance, the basecoat flashes so fast if you have a uniform pattern in your metallic it stays there.As for brand ask around in your area cause paint lines are just like hamburger joints everybody has a preference and sometimes a no name mom and pops cafe is best. I use a paint made down the road in Canton Ga. They don't sponsor a Nascar team so it is affordable and gives excellent results. In fact it is the same paint Year One puts on all their cars including the Chip Foose 69 Camaros they are building from scratch

[horsewidower]

Does anyone have experience with the water based paints that serve as a base coat for a bc/cc paint job?

[canadian_fly]

Would like to add another request for more informative information, and I hope I'm not jumping the tracks to much for this.

There seems to be a number of variables to painting. Temperature, moisture (humidity), solvent ratios, weakest link (1K vs 2K), this only to name a few. I was wondering if there was a simplified understanding of the causes of all the mistakes that are made? Orange Peel is caused by.... Fish eye is.... The clearcoat peel problem.... Runs.. etc?? I have the basic beginners understanding but with so many variables and some many those variables affecting each other, what is the best way to watch out for the common errors. There must be a "sweet spot" for all these variables and following the manufactures guidelines would help that, but what happens if the temperature changes, and how much of a change would greatly effect the painting process? A rise/drop of a couple degrees would effect the results by how much? a lot, not much? Can I offset that change with a fluctuation of Humidity. Eg. Hot day and low humidity? what does a hot day do to the dry time besides speeding it up. Do I change my ratios and by how much?

Not looking for the definite answer of this but if I can keep as many of the worst variables consistent then, I'm guessing, that I would have a better chance. Maybe....

Thank-you all in advance.

Ps. Will be requesting the "Spray Painting 101" 2hr DVD from Stuarts Autobody Store to learn more

[gigem75]

just wanted to say thanks for the info, that and the links realy helped with my first attempt at a base clear finish.

[Biba69]

This is my first entire painting of a car in 2 stage. I've painted numerous 2-stage wheels. My major concern, at the moment, is issues (aka bugs) in the clear coat. On the enclosed photo of an area on the front of the hood, the issue on the left is a major divot caused by partially removing a bug on the second of three coats of clear. The one on the right is an embedded bug on the final coat but goes down pretty deep (I did a bit of scratching after taking the photo).

The color is the Alfa medium silver metallic. For now the clear has been color sanded with 1000. I've spotted in (after drying) small divots in single stage paint and it works fine. I assume I can do the same with clear? Any other suggestions - short of repainting - especially if it is a sure fire way to get rid of embedded bugs?

Though it is pretty faint, I have an area on the front cowling which bothers me. If I respray the panel, I'm concerned that where I join the fenders (I cannot blend to save my life) the paint thickness will be at different levels.

Except for bugs in the clear and the tedium of spraying six coats, I really like 2-stage. I was amazed that after final polishing scratches were simply not a problem.

One more question: To get a deeper shine, do any of you spray three additional clear coats after sanding down the original three? Is it worth it?

Biba

[AlexGS]

With the paint system I use (DeBeer), it is unnecessary to have more than two coats of clear, which makes it particularly good where there's a great chance of contamination.

I apply the basecoat in several thin coats, making sure the metallic pattern is consistent. Then I clean it with a tack cloth, and spray a medium-to-thin coat of clear. A thin first coat is a bit less likely to give fish-eye problems. Wait 15 minutes - the clear is usually touch-dry enough to use a tack cloth again by that point - and finally apply one, heavy, even coat to ensure the orange peel flows out. I stand by with the tweezers for a while, then I close the garage door and run away...

The second heavy coat does give a great risk of runs and fish-eyes (craters caused by silicones or other contamination, which are never a problem for the primers or basecoat and only a problem for the clear...), but at least you avoid the need for two or more layers of dust and bugs, and can get less orange peel overall.

-Alex

[AlexGS]

Quote:

Originally Posted by Roadtrip Great writeup! A lot of 80s-90s model cars seem to suffer from spotty clearcoat breakdown. Can they be repaired somewhat satisfactorily at home, or is that futile? What causes clearcoat problems?

[Cintos]

Greetings:

My Duetto is in the process of being repainted, as discussed in another thread here in the restoration forum.

I would like to discuss a topic more relevant to this sticky thread, so I am posting here. The thread is quite detailed, but does not cover the issue of finish painting over the various types of primer coats.

My process flow was to first get the car media blasted, then primed in epoxy, then have any relevant panel restoration done, then get the finish paint applied.

I am now faced with an unfortunate reality: the paint can't go over the previously-applied primer due to the time lag - it needs to be fully scuff sanded to allow adhesion. Even then, the finish coat will be making a mechanical bond with the primer, rather than a chemical one. On the outer body surfaces, sanding seems straight forward, but for all the other surfaces - inside the wheel wells and engine bay, it seems it would be almost impractical to scuff-sand with a high degree of success in corners, nooks and crannies.

One thought I have been having, and discussing with the shop, is to simply do another media blast and get back to metal, then do wet-on-wet primer/final. Not surprisingly, the cost of a reblast may actually be less than the $$$ for all the sanding man-hours and material.

Am I being obsessive here? Any recommendations?

- Michael

[aralfa8589]

Michael-
You're talking about the high build primer (possibly polyester) used after the bodywork rather than the epoxy primer, correct? Or both?
Either way, the color coat bond is primarily mechanical. You'll be able to scuff nooks and crannies with a 3M Scotchbrite or similar. I'd go over the rest of the car lightly with 600 wet on a DA. A good wash and it's ready to go.

[Cintos]

Greetings:

Thanks for the advice. 95% of the primer we are speaking of is the epoxy laid on right after the media blast back in May. There is little body work, thankfully.

After several discussions, I am planning on staying with the "mechanical" approach to moving forward, rather than re-blast and wet-on-wet. I am told that wet-on-wet primer/finish over bare metal would be a superior approach, but if anything but very minor filling is necessary, the process falls apart.



- Michael