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  • scratches

    I'm using a high gloss TGIC black and noticing small micro scratches in the finish product. These scratches develope after wiping lint or dust off coated parts. Even if there is nothing on it you can take a soft towel and this will still leave scratches. Manufacture recommended cure cycle is 10 min. @ 400 degrees. I don't start the 10 min. cure cycle until the part reaches 400 degrees. Iv'e even doubled the cure time to 20 minutes and still get the same result. Solvent rub test has shown coating to be fully cured. I have heard that high gloss blacks are prone to these scratches. Is this true? With these being motorcycle parts, is there a diffirent type of powder that should be used? In some cases the powder must put up with high engine temps. Any comments welcome.

  • #2
    Re: scratches

    first off welcome to the forum.
    from my experience black is prone to show scratches. also in addition to the solvent test you may want to do a scratch test with a fingernail in a inconspicuous place. if it scratches (indents) the powder, it is under cured. it should be able to withstand most temp ranges that will come in to play on most motorcycles, except exhaust temp. that requires high temp or ceramic coating. i have not yet, but others i know, have had good luck with standard powder, doing cylinders and heads as well as cases on cycle engines. lastly not to dispute the manufacture but all the powder i have used is at least 20 minutes cure cycle.
    when in doubt polish it out/ why replace it when you can refinish it
    G2 Polishing and Powdercoating

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    • #3
      Re: scratches

      Thanks for the comments and the welcome Pickleboy.

      Manufactures data sheet calls for the 10 minutes @ 400F. Sprayed a few test panels today for DSC testing from powder manufacturer. Can't scratch the coating with a fingernail any more than with a towel. What about a clear coat over the black? Any potential delamination or clear discoloring issues to consider?

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      • #4
        Re: scratches

        Can someone give me more detail about the solvent test?

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        • #5
          Re: scratches

          Originally posted by SheCoats
          I'm using a high gloss TGIC black and noticing small micro scratches in the finish product.
          Ya man I though I was the only one that that happened to. I wiped these with a cotton rag and almost [email protected] myself It was't bad and not everywhere but they were there. I even showed them to the dude He said man that ain't [email protected] these look great how much I owe you. But it always bothered me. I feel better now thanks LOL
          Attached Files

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          • #6
            Re: scratches

            Originally posted by SheCoats
            Thanks for the comments and the welcome Pickleboy.

            Manufactures data sheet calls for the 10 minutes @ 400F. Sprayed a few test panels today for DSC testing from powder manufacturer. Can't scratch the coating with a fingernail any more than with a towel. What about a clear coat over the black? Any potential delamination or clear discoloring issues to consider?
            typically speaking if you have a full cure on the base coat then the clear should lay down nicely and cure with no problems. i generally hot shoot all my clears so as to see the gloss build as i go. i have not had a problem yet. as for discoloration that should not be an issue as long as the powder types are the same and the clear is not over cured. lastly when i do blacks i let them cure in the oven for the full cycle and then turn the oven off and crack the door and let them cool slowly. then when fully cooled i remove them and go straight to a coat of high grade wax. polish that up with a chamois or very old soft t shirt and no problems. some still have those micro scratches but that is a side effect of high gloss colors in general i feel.

            wamontgomery the solvent test is done after a full cure cycle to test the finish. on a full cooled part using a soft cloth and acetone or mek on the cloth rub the finished part in the same spot for about 30-50(opinions vary on this) strokes. if the powder is properly cured it will not color bleed on the cloth and will not fade. if it does it was not fully cured.
            hope this helps.
            when in doubt polish it out/ why replace it when you can refinish it
            G2 Polishing and Powdercoating

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            • #7
              Re: scratches

              As Pickleboy stated, I've heard of a number of different methods for solvent tests. For poly's I used a 10% MEK/90% Xylene mix for 50 double rubs. No effect on the coating. After that I tried MEK alone. Usually only use that on epoxies but it didn't cut through the TGIC. It did soften the surface but if it wasn't cured I would have expected it to go down to the part or at least make a mess.
              Think I will try Pickleboy's suggestion of waxing before any handling. I have waxed after the fact and it does help hide.
              Anyone tried a different type of gloss black powder that resisted scratching but was still had good weathering properties?

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              • #8
                Re: scratches

                Thanks for the info about the solvent test!

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