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  #16 (permalink)  
Old 04-27-2012, 06:35 PM
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Brian Martin,Freelance adviser
 
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Quote:
Originally Posted by Localboy808
Hey Brian, first off I always enjoy reading posts from guys like yourself that I can tell know what they are talking about! You bring up great points. But you got me thinking that the quality of his clear may be a factor. My first paint job came out great. But I'm wondering how I didn't get a dull finish myself. I was using a Matrix brand Euroclear with medium reducer. Well by the time it was time to shoot my clear the weather went bad! Temps dropped to 49deg and it was raining outside! I set up 3 halogen work lights in my garage to try and generate some heat. I didn't want to hold off because of the recoat time coming up. So I went for it. I did wait 45 mins between the two coats of clear. And it was not tacky by the time the second coat went on. I was going to go for a third coat because I did plan on color sanding. But it looked so good after the second I didn't want to chance a third and mess up! . Plus the can said two wet coats. In the end it was enough to color sand and looks great.

From what you are saying I'm suprised my clear did not dull. May e I waited long enough and the heat from the lights helped? Maybe my clear was of better quality than the Nason?
Look back at the ways you can trap solvent. The only ones that you had for sure were 4 and 5. And even then we don't know because the metal temp may have been up before that cold snap and it held out.

But what if you had those numbers 4 and 5 but handled all the others perfectly? What if we bombed on clear real heavy as in number 1 and 2 but then let it flash a super long time as in number 3, you "could" get away with it. How about the fact that you applied only two coats, that is a BIG one. That right there may have saved you big time.

To tell you the truth you did a fine job at handling all the circumstances and that with a little luck it all worked out well.

Honestly, three coats of these high solids clears is really pushing it. And if applied correctly so it doesn't have to be cut flat you really aren't removing much material even if you do cut and buff it, 2 coats should be plenty on the average repaint.

You want a kick but cut flat perfect finish then three is fine.

I have seen clears applied so heavy you could put your finger nail into it days later! And we are talking spraying it in 100 degree weather! I am not kidding you, went to a tech call on a guy who shot a Mustang black bc/cc and the clear looked like he put a pint of white toner in it, it was that milky looking. The clear was so soft I could press my nail right into it. I had him sand it with 600 and then put it out in the sun (100 degree minimum) for a week or so and it hardened up. He sanded it again to be sure and re-based and cleared after some instruction and it turned out fine.

Proper application can help overcome a multitude of other issues.

Brian

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  #17 (permalink)  
Old 04-27-2012, 06:35 PM
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Quote:
Originally Posted by MARTINSR
And here comes another opinion.

Guys, think about this, the clear going dull (die back) is caused by too much solvent being trapped. The top kicks and the trapped solvents escape by breaking thru the top layer and killing it's shine. Just how in the world are you going help end this by painting it so wet it is about to run?

THAT is exactly how you get die back, by piling on too much product too fast trapping solvents. Spraying it on so wet as to almost run is doing just that, it's piling on too much.

If you are getting die back you need to cut back on the amount of solvents trapped in the film. How do you do that?

1. Atomize the clear properly so when it comes out of the gun it hits the panel and the majority of solvent is flashing off.

2. Use a faster pass with less overlap.

3. Leave it longer to flash off between coats.

4. Shoot it in warmer temp shop and METAL TEMP (an ice cold car sprayed in a warm room/booth is no better than a cold room/booth) so the solvents flash properly.

5. Chose the proper reducer and hardener for the metal and booth temp.

6. Apply fewer coats.

One of these could cause an unwanted trapped solvent problem but it is often a combination of a number of them.

Brian
I've used Matrix for years and there is nothing wrong with reducing it (must use the proper reducer for the temp). Just because you are on the verge of running does not mean you are applying to thick of a coat. Especially if you reduce it 10%. You are supposed to overlap 50% otherwise you can run across problems with orange peel especially in warmer temperatures. The only time you have less overlap is if your painting Kandy colors!!! If you wait too long you can run across adhesion issues. Also, you should never paint if the metal and booth is less than 65 degrees. Brian is right about many things he stated but I've painted many cars using different paint systems including Matrix with this technique (with the exception of reducer, I have not always added it) and never had a problem. I might add that the shop I worked at that used Matrix wanted THREE coats of clear. I admit it is unnecessary unless you play on doing a lot of wet sanding. The point is we did not have a dullness issue.

when we ever had a dullness issue, the clearcoat or hardener was at fault, not the technique.
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Old 04-27-2012, 06:50 PM
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Brian Martin,Freelance adviser
 
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Quote:
Originally Posted by caryw1980
I've used Matrix for years and there is nothing wrong with reducing it (must use the proper reducer for the temp). Just because you are on the verge of running does not mean you are applying to thick of a coat. Especially if you reduce it 10%. You are supposed to overlap 50% otherwise you can run across problems with orange peel especially in warmer temperatures. The only time you have less overlap is if your painting Kandy colors!!! If you wait too long you can run across adhesion issues. Also, you should never paint if the metal and booth is less than 65 degrees. Brian is right about many things he stated but I've painted many cars using different paint systems including Matrix with this technique (with the exception of reducer, I have not always added it) and never had a problem. I might add that the shop I worked at that used Matrix wanted THREE coats of clear. I admit it is unnecessary unless you play on doing a lot of wet sanding. The point is we did not have a dullness issue.

when we ever had a dullness issue, the clearcoat or hardener was at fault, not the technique.

I said nothing that disagrees with what you have said. What I am saying is IF you were to apply it that wet (near run) you had BETTER have all the other reasons for trapped solvent under control!

1. Atomize the clear properly so when it comes out of the gun it hits the panel and the majority of solvent is flashing off.

2. Use a faster pass with less overlap.

3. Leave it longer to flash off between coats.

4. Shoot it in warmer temp shop and METAL TEMP (an ice cold car sprayed in a warm room/booth is no better than a cold room/booth) so the solvents flash properly.

5. Chose the proper reducer and hardener for the metal and booth temp.

6. Apply fewer coats.


And if you do all the things proper with proper atomization you more than likely don't need to over reduce it.

It's like I aways say FOLLOW THE TECH SHEETS. If we were to follow the tech sheets to the tee, it is going to work. If one has to deviate from the tech sheets for a particular "only in my shop" kinda problem, sure, not a problem. But you can't deviate from the whole tech sheet, it simply isn't that forgiving.

It's like many things in life, you can go and hang out on the edge of the line on something and it will work fine, but you can't hang out on the edge on EVERY line. You know what I mean?

Believe me, we are on the same page. If I have communicated it wrong, that's on me. But we are on the same page.

Brian
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Old 04-27-2012, 07:25 PM
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Brian Martin,Freelance adviser
 
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Quote:
Originally Posted by Localboy808
But you got me thinking that the quality of his clear may be a factor.
I didn't mean to skirt this issue, of course it could be that the clear he is using is part of the problem.

I say "part" of the problem because it doesn't do this on every single job it is used on. If it did they wouldn't sell a bit of it. It works somewhere for someone.

Often it's more about "the planets being aligned" where there are more than one seemingly little issue is aligned with other seemingly little issues and combined you get crap.

Brian
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Old 04-27-2012, 08:12 PM
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I've heard a lot of good things about Matrix never anything bad ,I've never used it myself .
when it comes to newbies theres always the luck factor, some guys can do everything wrong(like me) and still get a good job. I've always been lucky when it comes to paint...One time I ran out of clear hardner (not to long ago actually)on my last coat and substituted about half of it with a primer hardener without any problems at all ,I totally expected it to do something crazy but it didnt ... it was sunday night and the car had to go monday at noon so if it wasnt ready there was going to be a good reason that I could blame on the painter (me, but they dont know that) not something lame like, sorry I ran out of hardner you'll have to rent that car another day...a little prayer to the paint Gods when I do something I know is stupid cant hurt either and I do it...But I still do some major screw ups like mixing 1:1 sealer at 4:1 y,ou want to see a clear get dull try that sometime or put to much base on way to thick and without realizing it and rush the clear because you want to get home ,it looks great when you leave but when you come back the next day and no shine at all...Theres a lot of ways clear will dull out even the temp change at night can do it..
Who knows what the actual cause was ,all we can do is make an educated guess..pay your dues when this stuff happens and do it over being double sure you follow all the directions to the tee.You can only get better..
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