Respray question

[tandy ass]

Forg, what I've learned in my limited experience of spraying my car and a few others is the acrylic based paints can also be referred to as 'single pack' or in other words only one chemical solution. These paints go hard by evaporation of the thinners and other evaporative compounds inside the base coat.

2 pack goes hard by means of curing of two seperate chemical compounds, the 'hardener' and the basecoat/thinners. The hardener is the one thats really bad for you, containing the free icocyanites.

2 pack can only be left in the gun for up to an hour in mixed form or it will start to solidify. Acrylic can be left mixed in the gun for months and all it will require is a restir when ready to paint again.

Some paints are simple basecoats that dont require a clear, example some whites and blacks. The colors I've painted always require a clear such as reds. They are called COB paints (Clear Over Base). The red I'm painting my car looked bloody awful off the gun but as soon as the clear was applied then it looked a million dollars. The clear needs to be applied within a limited timeframe of the basecoat color application so it will chemically link itself with the basecoat to form a very glossy and solid finish.

There are people in here with far more knowledge than me so please correct me if i'm mistaken

[mopar lover]

Bozz is absolutely correct, 2pak is called that due to the 2 components required. Although the with the COB system the Base is very much similar to acrylic (BUT IS NOT THE SAME). Also laying on heaps on paint is BULLSHIT! Too much paint thickness makes it more prone to chips and cracking.

Also 2pak is better due its tougher surface strength derived from a chemical reaction not solvent evaporation like enamal and acrylic. But 2 pac really needs some form of downdraught booth, everything sticks to it really easy, worse than enamel. I know this from experience! Also ovens do not harded or improve the strength of the paint this is a fallacy, it only reduces drying time, which is money in a panel shop. Because of time 99% of all paint repairs in my opinion are average at best. Those sanding marks I bet are 'sink back', insufficiently dried primer (which was smooth) after a repair, which is then top coated.

As for respraying a new car, look at the new BA Falcon a lot have been seen with "spray strokes" on them even though they are mechanically painted! Especially noticable are the metallics in the sun.

2pak can also be blended very easily and successfully, acrylic is the same also. The blend is "flicked" through. It will be very "peely" which is blended by putting reducer into the gun and gently spraying to smooth the peel.

Also in panel shops they always try to imitate the factory peel, imagine a glass smooth repair against factory peel paint. They use the buffers to smooth and blend the repair, the wax just acts as a shield. The best waxes are just pure carnuba wax, applied finally after the paint has been buffed.

[GTI124]

Would a photo help of what the problem is with my bonnet? I have no doubt it needs a respray.

Thanks for all the information, it's very useful to know the process so that the wool isn't pulled over your eyes over regarding the work. Hence why I was wanting to know if it was normal for a large amount of work to be done on the panel after the clear coat. If it's just to get the same amount of peel...and Pugs tend to have a decent amount of orange peel, then that sounds fair enough...I'd prefer it to be mirrored and to get the other panels to look the same though...

[mopar lover]

If it looks like they just sanded the panel then layed on top coat, then thats sink back (unless they work stoned). A well prepared, CLEAN surface can be just top coated over if you wish. But since you say it chips easily, sand it back, re-primer, sand, the top coat. Leave at least 24hrs between primer and sanding. Longer if the weather does not exceed 25 degrees C.

Don't be suprised to find that they just slapped primer over the original paint with minimal sanding (normally causing weak substrate strength, hence easily chipped.

You can post up a photo of the panel but if it is metallic it can sometimes be hard to see properly.

I have never ever seen a painter actually paint with zero peel. The best I have ever seen is a slight ripple effect, as far as I am concerned its impossible. Also to its easier to smooth out peel then trying to remove runs.

[tandy ass]

mopar lover, how do you get less peel with 2 pack paints?

I found I get a fair bit less peel on a horizontal surface compared to a vertical surface, is it because a bit too much paint is applied and it starts flowing downhill and stopping as it cures?

What state are you in?Cheers

[mopar lover]

I am in QLD.

I am not a professional spray painter, I have taught myself as well as getting advice and tips from professional spray painters I know.

Peel is not bad as long as the paint thickness is good, i.e enough to allow a 2000 rub and buff. Aiming for near zero peel can be dicy even for professional painters due to runs ,I know a professional painter who cannot ever spray without runs and/or 'standing up' the metallic.

Removing a run is very hard because if not done carefully you'll rub through in the surrounding area and normally there is still an impression.

Peel in general is controlled by how much reducer used, air pressure and your own spraying action. Thats why the reducer percentages are in a range, to allow for different spraying techniques. Its best to practice on a clean scrap fender first to find what suits you. The more reducer remember the less peel at a greater risk of runs, try about 10% as a start then go up untill it gets too hard to control (runs) then back off a bit, I don't recomend over 25%.

Like it is nice to sit back and think shit I sprayed it perfect off the gun first time. But as long as you follow all the basic rules, lay on enough paint, the rub and buff WILL produce the results you are after.

[GTI124]

Thanks Mopar, very helpful info.

The panel would've been a brand new panel as it would've been an insurance repair from the previous owner. So to me it was just shoddy prep work and shoddy painting...all round shoddiness :D

I'll try and take a pic this weekend and post it here so you can see it. Everytime I wash the car I find a new chip, just doesn't seem normal that paint should chip this much...

What does a painter do if they get a run? Do they sand it all back and do it again? What's "normal" practise for getting rid of a run? Can you get rid of a run once the paint and clear coat has dried?

[mopar lover]

One guy I know blows it with compressed air while still wet to smooth it out. I never saw it but I would think you risk turning a small run into a giant sag. Which is harder to fix due to larger area.

Generally most panel shops use small hard blocks backing 1500 and wet rub it out then buff like normal.. The hard bit is not taking out too much paint from the surrounding area (breaking thru). There is also a titanium block that can be purchased to remove the bulk of the run before blocking it back. Its about 1.75"X1"X.25" and it costs about $90-100.

Just letting you know, the main reason a car gets detailed after the paint job is to fix these stuff ups a lot of the time. If you saw the repair on your car straight after the top coat you would tell them to do it again. Thats the reason a lot of the panel shops don't allow customers in the workshop. I have seen this with my own eyes in probably one of the largest panel shops in QLD.

In COB (clear over base) systems it is generally harder to get runs in the base. Your only after even, consistent coverage (not shinny) and it sprays on like acrylic (drys quick). For example you can touch the base in about 20min and clear it in approximately an hour. With the clear its not so bad, you can easily add more clear. Although if you break through the clear you need to blend/respray.

[GTI124]

Just to clarify, when do you get rid of the dribble, before or after the clear coat? If after the clear coat, can you get rid of a dribble 12 months after it was painted?

[Captiva Fan]

You have to get rid of the dribble after the coat that dribbled, and before the next ... although I suppose if you put two coats on & the run occured in the first, you might still get it out. It's basically a matter of sanding down the raised paint of the run, without sanding down the paint around it, and making sure that sanding is finished-off with the same texture as the paint around it. Obviously, if the run is in a colour coat that's buried under a clear coat, you probably can't do mcuh with it.

[GTI124]

thanks Forg, that confirms that I need a respray on my fender...someone keyed that fender as well, why couldn't they keep keying around onto my bonnet???

[RXTION Ben]

good reading there guys..

I am going through something similar at the moment, while i dont want to hi-jack the thread, i have a question.

Im getting my car back to bare metal.. the whole car - (See avatar) im doing the stripping myself using paint stripper, wat do u reccomend i do to prepare the metal?? i am currently using a orbital sander with 240grit paper to "ruff it up" then spraying with a 1pack etch primer to protect the metal, ready to goto the spray shop for dent removal and the final spray in 2pak, im using the 1 pack etch primer as the spray shop will need to take it off themselves anyway to fix the dents etc.

am i preparing it the right way? any reccomendations?

cheers guys

Ben

[tandy ass]

AU Crew, if you're stripping the car then spraying the single pack etch primer on, why do this when the spray shop will have to do the same thing again? Just take it straight to them and get them to do the whole nine yards.

[GTI124]

agreed

[mopar lover]

Sorry about the slow reply.

Forg is pretty much right about the run removal. Although with the COB systems it is harder to get runs in the base. Really you do not want runs in the base, especially metallics which can be hard to blend in evenly/discretly. You must remember the gloss is in the clear not base.

As for priming the car you should prime bare metal ASAP. It can surface rust as quickly as 1 hour if the environmental conditions are right! The metal should be treated immedialy with a metal conditioner, its only phospheric acid I think. It is important to follow the directions.

Theres nothing wrong with priming the car before giving it to the body shop. Imagine if it took days before they actually started work on it. Everytime the bare metal gets touched/ fondled by someone's hands it will surface rust easily in 1/2 a day. There's no way the car could be taken to the panel shop without being touched as far I know.

Also you should generally try not to leave a car in primer for more than 2 weeks. Primer slowly leeches moisture out of the air, bog is worse. There is an epoxy primer that you can use if you need more time, it won't absorb moisture at the cost generally of tougher film strength. Meaning its tougher to sand, work with and it cost a little more. The black primer paint jobs of the 60's-70's are normally this paint.