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Yep, I need help with another powder defect!

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  • Yep, I need help with another powder defect!

    This PBTP Trans blue over CC black chrome.

    I've still been having a lot of trouble with my King Coat gun back ionizing on me, so I first tried to shoot the blue when the valve cover was about 150 degrees. I was still getting bad back ionization so I heated up more and shot it at about 225-250, and it still back ionized in several spots where I could see the powder star bursting before it melted and after it cured those spots where the star bursts were much darker. But these wrinkled spots are where there was not back ionization at all, you can't see any of those spots in the pictures.

    But back ionizing aside - it came out with those wierd wrinkles that I have never seen before. I don't have much experience with hot flocking, but I don't think I put it on too heavy because the color was pretty uniform and there were no sags or runs anywhere.

    I briefly mentioned to to Shelly when I talked to her on the phone the other day and she said it was probably caused by shooting the powder while the part was too hot and that 250 is way too hot to hot flock at.

    Don't mind all the dust lol, it's just been sitting around for several days.






  • #2
    Re: Yep, I need help with another powder defect!

    Please go through how you cure your powder EXACTLY. Lets start with just your base coat.

    Comment


    • #3
      Re: Yep, I need help with another powder defect!

      Oops, I meant to mention that above. But I shot the CC black chrome with the part cold and cured at 400 pmt for 20 mins. I then started to shoot the trans blue when the part was about 150* and had instant back ionization before I hardly got any powder on - So I put it back in the oven to heat it up more and then shot the trans blue close to 250*. I then cured at 375 for 20 mins.

      Comment


      • #4
        Re: Yep, I need help with another powder defect!

        Do you use IR guns or no?

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        • #5
          Re: Yep, I need help with another powder defect!

          Yep, I always go by the IR temp reading on the part.

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          • #6
            Re: Yep, I need help with another powder defect!

            Originally posted by caseywan
            Yep, I always go by the IR temp reading on the part.
            So the part was 400f by the IR gun and then you clicked the timer for 20 minutes>?

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            • #7
              Re: Yep, I need help with another powder defect!

              Yep.

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              • #8
                Re: Yep, I need help with another powder defect!

                What's your thoughts?

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                • #9
                  Re: Yep, I need help with another powder defect!

                  Originally posted by caseywan
                  What's your thoughts?
                  Why did you cure the base coat for 20 minutes? I am not familiar with that product.

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                  • #10
                    Re: Yep, I need help with another powder defect!

                    My thoughts are this.

                    Base coat possible under cure.

                    Base coat on too thick.

                    Why are you hot flocking?

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                    • #11
                      Re: Yep, I need help with another powder defect!

                      I know the base coat was fully cured - I cured it at 400 pmt for over 20 mins and it calls for 375 for 15 mins.

                      Base coat was not all that thick - I've used it quite a bit and it was not too heavy.

                      I am hot flocking because my King coat gun is still back ionizing horribly at times (stated that above a few times).

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                      • #12
                        Re: Yep, I need help with another powder defect!

                        Then I have no clue bud....

                        Back anodizing can also be cause from too much powder as well.

                        Anyone else have an idea? I am lost on this one.

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                        • #13
                          Re: Yep, I need help with another powder defect!

                          Weather/humidity is definitely a factor with the Back ionization. Here is how the problem can be virtually eliminated. turn the kv all the way down on the controller and increase the air/powder flow. Start spraying the part and slowly increase kv until you begin to get attraction on the part. Now spray the part in a quick motion across the part if you have some areas that still dont want to attract try pulsing the trigger and putting the powder onto that area a little at a time until it covers. Now you will waste more powder than normal when you are having this problem. This will mainly happen on second coats and its basically like you are doubling the kv that is charging the powder when the humidity is high.

                          We just worked through this yesterday and I was having the same problem with both my gema and the king coat gun. The back ionization was so bad that you could stop spraying powder stand back and watch the pin holes just appear. Made these adjustments and layed down three coats cold, and then base coat / topcoat on a test panel cold.

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                          • #14
                            Re: Yep, I need help with another powder defect!

                            The wrinkling in that part is either from incompatible powders or under cured basecoat.

                            Comment


                            • #15
                              Re: Yep, I need help with another powder defect!

                              Originally posted by Harleydad
                              I suspect the film build is too high due to hot flocking and that the part was too hot when you did it. I'm just curious, did you spray the part hanging and lay it flat to cure?
                              What kv were you spraying at when you applied the trans blue? It looks as if there's virtually no powder around the lettering.
                              You really need to figure out why you're having all these back ionization issues. Maybe JNZ could offer up a few tips on the gun. He seems to have his working nicely.

                              Joe, any thoughts?
                              That was my first thought that the film build was too high and it was sagging. But I shot the part hanging and flat and hung it to cure, and some of the wrinkled spots looked to be against gravity, so I didn't think that was it, but possible.

                              I was shooting the part at about 15-20KV - as low as I can get and still charge the cloud.

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