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Old 10-06-2003, 12:06 PM
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Why Rock Chips?

Yea, I know, don't tail-gate.

Really, a couple of years ago I painted my truck using PPG's materials. I used DBU base coat and applied DCU2042 clear coat. The DCU calls for 4 parts DCU: 1 part DCX61 (hardener) and reduced with 1 part DT reducer.

I applied the materials as directed using an HVLP gun in my garage. I was really pleased with the job and it color sanded and buffed out really well.

Two years later, I am getting rock chips that seem too prevalent for the careful use it gets. I admit that I have driven it fast in traffic a couple of times, but basically, compared to some paint jobs I have had done professionally, the paint seems more to likely to chip than say the Sikkens job done on a sports car recently.

Am I using the wrong top coat or should I not be using the hardener? What is the trick to reducing rock chips?

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Old 10-06-2003, 12:36 PM
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Usually rock chips are due to thick paint. The thicker the more prone to chip. Are they big chips, or little flecks? If they are big, definately paint thickness. But, I am not expert.

Chris
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Old 10-06-2003, 12:58 PM
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They are not large, typically pin head to twice that size.
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Old 10-06-2003, 02:18 PM
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I don't use PPG as much, but have noticed more chips on cars that had too much hardener- this doesn't seem to be your case as you went by specs, buy overly hard paint will chip easier also. The film thickness response is a good cause, too.
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Old 10-06-2003, 10:02 PM
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why rock chips

Hey F1 ,
Sounds like you are experiencing NORMAL wear & tear .Even if you are extremely careful, there is no way to stop rock chips ,speed isn't usually a factor . All you need is someone in front of you with a rock in their tires ,or even sand on the road .
Just look at the sand pits in your windshield if you don't believe, and think how hard IT is . Judging from the size you describe ,I'd say it was coarse sand . Anyway, my guess is that paint thickness is probably the culprit here ,some times we all get a little carried away with paint application . So , don't get discouraged , just drive your 'baby' and enjoy it . After all ain't that the name of the game? Rick
P.S. When you mix paint ,keep in mind that when they say so many parts to so many parts---they mean VOLUME ,NOT WEIGHT, many people make that mistake .
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Old 10-07-2003, 04:52 AM
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3M makes a thick clear self adhesive film that can be placed on areas that are prone to being chipped, like the front edge of your hood. The stuff is designed to be permanent, but can be removed. It is for people who detest bug shields.

Vince
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Old 10-07-2003, 09:01 AM
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If you drive behind other vehicles paint chips are part of the deal. Cars with rubber noses tend to chip less because they allow the paint to flex a little more. My 89 Mustang has every square inch of the hood peppered from rocks and sand and who knows what else bouncing off of it on my daily commute on 1-95, about 50 miles total each day just on the interstate. The rubber bumper on that car has faired out much better though. The windshield looks like it has been sandblasted when viewed through the morning sun. My 78 Camaro with a flex additive-lacquer paint on the rubber nose has almost no chips and that paint job is 17 yrs old, go figure. Painted sheet metal on the front of a vehicle never seems to fair out that well.

Even slow driving around town will find chips from stuff thrown up by other cars not just dump trucks! If it really bothers you try using a front end bras on longer trips but don't use it all the time because it will leave marks on the car.

Scratches and chips are a part of life no matter what your paint thickness or type of paint is.
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Old 10-07-2003, 09:27 AM
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Yep, as bad as it sucks, rock chips are going to happen. Kindof like door dings. If you drive it long enough some ********* is going to ding it.....if you dont first. It is so painful to see thought isn't it. Just like a punch in the gut when you chip that new paint. My S-10 already has a few little nicks I have had to patch up just from working on it, and it has never seen pavement. My 57 is peppered all over the front and around the wheel wells.

Chris
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Old 10-07-2003, 09:39 AM
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Like the time I graciously offered to give a jump on a dead battery for a secretary in our office. Pulled up close enough to her car to fit the jumper cables and she opened her door so hard into my Willys hood that it exposed the fiberglass strands!

Incidentally, did you know that glass is technically a liquid? It is one of the few solids that has random molecule distribution, no crystalline structure.
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Old 10-07-2003, 09:43 AM
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Well, I was sort of hoping that a professional painter type would come on the board and tell me to use a flex agent or to delete the hardener on the paint applied to the front of the car or some chemical/ mechanical solution.

So far, I have only come up with the idea of applying a set of flames to cover up the chips to date.

Painters, where are you when I need you?
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Old 10-07-2003, 10:55 AM
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Adding flex agent is only a temporary fix to keep paint flexible while plastic parts are being torqued around during installation from what I have been told. Basically flex agent only remains flexible for a short period of time and eventually the paint reaches its original hardness.

As for removing hardner, that would be a no no as well. Hardner is a chemical activator that cures the paint. If you leave it out you will have a very big mess.

Chris
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Old 10-07-2003, 12:33 PM
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Most people who are really concerned about this problem run a bra. I've seen a few rods at rod runs that have tiny little bugs (pinhead up to 2-3 pinhead sized flies, bees, grasshoppers, etc.) painted on the dings. One of those was a prize winner at a recent NSRA Street Rod Western Nationals.
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Old 10-07-2003, 06:12 PM
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OK, I'll just take it out and smash a few bugs and clear coat it. I love winning the big trophys!
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Old 10-07-2003, 09:14 PM
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why rock chips

Hey F1 ,
I AM a professional bodyman/painter and have been for 30+ years. The answer that Turbo gave you is right on the head .There is no way to leave out hardener in any type of urethane paint & still get it to cure. Flex additives only slow the total cure time .And ,unfortunately, clear protective film is designed for small areas ,and is a REAL pain to put on correctly,unless you are a pro . I LOVE the bug decopage idea ,I have done that more than a couple of times ,but usually it is accidental ,& gives me fits!!!
Keep on truckin' , Rick
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Old 10-08-2003, 09:17 AM
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F1 Owner (Rick): thanks for the feedback. From your experience, are there any paint systems or brands that do a better job of resisting abraision?
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