So if you are spraying a single pack or 2 pack acrylic clear and its not adhering properly, that is you can get under a corner and peel sections away, is that more to do with grit choice between coats or the nature of clear coats.

If I for example paint some 2k black onto some 2k black a week apart, I cannot peel it, you have to sand to remove, but doing the exact same process with a clear coat, i can peel sections of the clear away.

Why can clear coats be peeled, i am also picturing old cars where the clear coat has started to lift and peel away

Steve

Are you spraying the clear over fresh paint?

The only times I have seen clear peel is:
1. If it has been sprayed over deteriorating base coat. That is base that had peeling clear removed and then fresh clear sprayed over the old base coat. The clear provides UV protection for the base. If the clear has failed the base is shot and needs to come off.
Example:

2. The clear is incompatible with the color coat.

Others may have more examples and reasons.

I,m not sure what you mean by 2K it gets used incorrectly a lot. so are we talking base clear, if so the base and clear are two different animals. the base is a lacquer type material and can adhere to its self providing all the stars line up. the clear is a urethane material and needs to be put over the base within a certain time window, to long and you'll get the pealing.
now if your talking S/S that's a urethane color with an activator. there should be no problems as long as the color coat has been sanded. there is also a window of time that you can apply the clear directly to the color. sometimes you'll run into a situation were there might be an activator problem. the color will have an activator and the clear will have a different activator. it should still work as long as its sanded. if you could please be a little more specific with your materials and how you used them.
Jay D.

'68 Coronet R/T wrote:If it has been sprayed over deteriorating base coat. That is base that had peeling clear removed and then fresh clear sprayed over the old base coat. The clear provides UV protection for the base. If the clear has failed the base is shot and needs to come off.

In my car reference that is exactly what i was referring too, so that has to have the base coat removed as well.

Steve

badsix wrote:if you could please be a little more specific with your materials and how you used them.
Jay D.

Hey Jay,

So I am painting my camaro slowly at home in 2k acrylic urethane?, its an off the gun solid colour full gloss made by a company called valspar. No base coat needed no clear coat needed.

They also make make base coats which are an acrylic and they have clear in 1k or 2k.

This same paint is what i use for spraying guitars at work, the guitars are where i have seen the issue occur.

If i have a 2k solid full gloss painted surface by me, and then decide to put a 1k acrylic over the top after keying in with marroon scuff pads, i find if damage occurs at a corner - like being bumped when its dry, i can actually peel small sections of paint almost like lifting a latex.

The same occurs if I use a base coat and follow up with marron scuff pad and put a 1k clear coat. Bump a corner when its dry which breaks the edge, allows you to peel back some of the clear.

In either situation, clearing over a 2k or 1k surface when dry and scuff keying followed up with a 1k acrylic, i find the 1k acrylic kind of struggles to adhere

Hope that was not too much info

Steve



Example,

could be something with the unactivated clear. also I don't believe you get good scratch with a scratch pad unless your really rubbing it. in your case it might be better to use 600 or 800 paper.
Jay D.

Steve, even I have been a bit confused with your terminology.

Just so we're all on the same page:
1K clear: A single component acrylic lacquer clear usually just called acrylic here, 1K or lacquer clear over there.
2K acrylic urethane: A solid colour, two component finish, usually referred to here as just 2K (after the PPG designation of the product that they had to complement their Cobra line. Younger painters who may not have used the Cobra/2K system will sometimes call it direct gloss. In North America, single stage, 2K single stage or direct gloss. Even though most brands are based on an acrylic formulation it's not usually called that to save confusion with single component acrylic lacquer which is also a direct gloss finish.
2K acrylic urethane clear: Two component clears come in a whole range of different formulations, some urethane, some polyurethane, some acrylic urethane and some acrylic. And then there are the hybrids that are mixtures of the different basic types. Confused? Well, join the gang. Unless discussing specific properties of one against another, just 2K clear, two pack clear or two component clear, the essential similarity being that they need a hardener, which is usually, but not always, contains isocyanate.

Now, your problem with adhesion.

1K acrylic clear needs to be put on over a basecoat within a window of time. Depending on the basecoat that can be from 15 minutes to a few hours but certainly not after it has fully dried. If it has fully dried then the basecoat needs to be scuffed and another coat applied before applying the clear, this time within the 'window' of time.

Basecoat should never be scuffed or sanded before applying clear (regardless of clear type) without reapplication of another coat of base - the scratches will be visible and if metallic or pearl then the flakes may be exposed, changing the look. Generally I would avoid a situation where the base is allowed to dry for too long before clear application because it really isn't intended to be sanded and tends to tear, plus it's very thin and may not cover scratching well.

Acrylic clear can be applied over any OEM type finish (say, if doing a blend) but the substrate should be sanded with P1200 wet first until all shiny spots are removed. Just scuffing with Scotchbrite isn't enough and red Scotchbrite will leave scratches that may be visible through the clear. Grey Scotchbrite with a scuffing paste may be an alternative but I don't trust it enough because it has to be done really well.

1K acrylic clear isn't always as bump resistant as a 2K clear (depends on brand and type) so, if you're doing guitars that tend to be used as smashing implements then a two component clear is probably a better choice.

Edit: Jay's already on it with the preparation.

Thanks, my apologies for incorrect lingo.

The joys of amateurs who offer painting services without really being a painter and truly understanding the ins and outs, my old man (79) shakes hos head at my questions, he was a painter by trade for 30 something years, but has alzheimers and forgets a lot of stuff now.

I always allow my base coat or 2k acrylic urethane to fully cure and then flat sand smooth and follow up with a scuff sand before clear coating, i have never reapplied another base coat before clear coating, this might be the option for me.

The reason i allow my base coats or 2k acrylic urethane coats to fully cure before scuffing and clear coating is I have never managed to get a dust free clean coat to start with, i always get something in my paint even though i have a paint booth, wear a suit, clean the floors and walls before spraying and so forth.

Guitars, people want a flat mirror finish, so no orange peel no imperfections etc, so I spend a lot of time sanding between coats or layers to get that flat mirror finish, with of course lots of buffing at the end

I dont seem to have bonding issues to much with 2k acrylic urethane clear, the bonding and peeling issues seem to be more prevelant in the 1k acrylic clear coats going over a 2k acrylic urethane, i think now i might just drop the colour coats (2k acrylic urethane) and just stick with base coats, allow to dry, final sand smooth and then flash a wet coat on again before clear coating in 1k acrylic clear or 2k acrylic urethane clear

Steve

Okay, so I'm just askin'......why do you put a final 1k clear over a 2k coating? A 1k lacquer product is pretty hot stuff (chemically). Depending on just which one you are using it probably just isn't bonding enough.....

I GIVE, this is to hard to understand must be an age thing here's my understanding please correct me if i'm wrong. 1k is anything that doesn't require an activator or catalyst, lacquer, synthetic enamels, 2k requires an activator or catalyst, urethanes.
for your guitars why don't you use lacquer products all the way through they are very user friendly and your final coat can easily be buffed to perfection.
Jay D.