Trouble with a hood scoop

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  • March 16, 2009 at 7:24 am #13384

    First of all, I don’t have any pics or vids, I know that’s a disappointment since it’s a show me kind of subject.

    I was given a hoodscoop to paint (twice). It’s a simple job, just UA (black)from Ford and was brand new. I had to do it twice b/c the first time the place we painted it for (NOT US) decided to install using only 2-sided tape lol. Hey great for us, 2 jobs instead of 1 is always better.

    So, first time I painted it I DA’d it with 320 then wetsanded with 400p. Then the boss had some Pla-stick from Dupont left over and I sprayed a couple of coats, then base/clear. I used the R-M base (403 black I think) then the Limco 4500 clear. It looked great except for what seemed to be a lot of trash. Except I don’t think it was trash b/c it was perfectly round bumps sporadically on the scoop. They came up as soon as I made the first pass of clear. And it wasn’t there on the base.

    Now, the 2nd time. I DA’d with 320 and wetsanded with 400. Then I put 2 coats of EP569 with the polyuroxy added 3:2:1. Layed down perfect. Then based with the 403 again, still perfectly flat and smooth. Then Limco 4500 clear and after one pass I see a couple of little bumps again. They look about like the bumps on a basketball, perfectly round.

    I thought it may be seeds from the clear’s hardner, but the second time the hardner had only been open a day and it has not happened to any other thing I’ve cleared, plastic or metal, except the scoop. I had just cleared a couple of motorcycle side panels right before that were not painted stock, but were sanded, epoxied with HOK then based with HOK black and cleared with the 4500 and no problems at all.

    All flash times were adhered to and hardner/reducer apropriate temps. Everything was tacked off prior to base coats and the base coat looked great before the clear.

    Any suggestions?

    OH BTW, hi guys. I’m sportbikepainter from autobody101.com. And that’s an ’04 Ferrari 575M I’m working on in the avatar.

    Anonymous
    March 16, 2009 at 5:27 pm #13389

    Don’t know if I have much help on this one, just wanted to say Its nice to see you here. The only thing that comes to mind when I see polyuroxy in the same paragraph with bumps is accidentally using DH42 with it. It sounds like your problem is specific to the clear, but I’ll share my polyuroxy disaster just in case something sounds similar. The tech sheet say’s right on it do not use dh42, only 46. Anyhow force of habbit I just picked up the 42 and used it, the polyuroxy turned all lumpy and sprayed with small bits out of it. Found out later it was because it reacted with the accelerator in the 42.

    March 16, 2009 at 7:54 pm #13392

    What were your flash times? What was temp? It just sounds like solvent pop.

    And i’m curious about this polyuroxy?! How much is it? What exactly is it?

    March 16, 2009 at 7:56 pm #13393

    Lets see some pics of that Ferrari! What you doin to it??

    March 16, 2009 at 8:56 pm #13395

    Flash times were 5-10 min with the base and whatever the can says for the primer. I have a kitchen timer I use. It was not solvent pop I’m sure.

    Hey Jimmo, glad you told me about the dh b/c I almost used the 42. If I had used the polyuroxy both times I might feel like it may be the culprit.

    The Ferrari just had a nice scratch on the quarter panel. The Polyuroxy is an extra ingrediant that’s added to R-M epoxy primer. I can’t really tell you what it does or I’d have to kill you…lol j/k I don’t know what it does. You can mix the epoxy with or without it though.

    March 16, 2009 at 8:59 pm #13396

    How long did you let the base flash before clearing?
    And what were the temps?

    Anonymous
    March 16, 2009 at 10:04 pm #13397

    Han, the Polyuroxy is an additive (BASF patented) that you add to your epoxy that makes it behave more like a urethane. Its sands easier and flashes/drys quicker. I’m sure it takes away something from being a true epoxy, but they still rate it much better then a 2k urethane.

    March 16, 2009 at 10:41 pm #13399

    Very interesting. How much is it? How much do you add? What is the build like?

    Anonymous
    March 16, 2009 at 11:02 pm #13400

    I don’t know if you can use the stuff in other products aside from basf. I think it was around $70-80 for a quart and it gets mix something like 3:2:1 epoxy primer:polyuroxy activator:urethane hardener

    The build is alright, not quite that of a descent urethane. I didn’t find it to sand as well either. I think the best use for it is as a wet on wet sealer. It gives a 25 minute flash and you have a very high quality sealer (direct to metal like an epoxy too). I wasn’t overly impressed using it as a primer surfacer.

    March 17, 2009 at 2:19 am #13407

    It does sound very interesting. Maybe, someday, they’ll get it right and urethane primers will be as useful as lacquer primer…

    March 17, 2009 at 3:22 am #13411

    Yeah it sands like crap as a surfacer.. I use it all the time as a sealer.. Works good, just have to make sure you let if flash for 20-30 mins..

    March 17, 2009 at 5:33 am #13413

    i would be interested to find out just how old the dupont plas-stix is….if it is not properly shook up each time it is used it will leave the tiny grit looking bumps on the surface ,this will actually etch themselves into the surface of the plastic .i have run into this before …also your plastic cleaner may have been to hot for the type of plastic you were dealing with …some plastics are a real pain..also it is never wise to start mixing different products together..since they all have different chemical properties .. designed to work with there own systems .. :blink: :blink: :blink: :blink: 🙁 🙁

    March 17, 2009 at 8:28 am #13420

    [b]lowder wrote:[/b]
    [quote]i would be interested to find out just how old the dupont plas-stix is….if it is not properly shook up each time it is used it will leave the tiny grit looking bumps on the surface ,this will actually etch themselves into the surface of the plastic .i have run into this before …also your plastic cleaner may have been to hot for the type of plastic you were dealing with …some plastics are a real pain..also it is never wise to start mixing different products together..since they all have different chemical properties .. designed to work with there own systems .. :blink: :blink: :blink: :blink: 🙁 :([/quote]

    Well, the pla-stic is kinda a moot point considering it was in the trash can the second time I painted the scoop. It’s either the plastic itself, the prep procedure or the base/clear because those are the things that stayed a constant both times. I’d really also rule out flash times and actual painting procedure. I paint 2-4 cars a day and have yet to have an issue with anything else. Not that I’m immune from mistakes, it’s just that the procedure was the same on the scoop as on everything else.

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