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problems with spyder webing

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  • problems with spyder webing

    hey i just now found out about caswell plating company. i have been using eastwood co. about a year. i cant get any help from them about powder coating. i think if a company is going to sell a product they need to know a little about it.i will be getting my suppies from coswell from now on. i like the forum page. maybe someone can help me with a problem i am having. i coated some fenders, with a base coat of almost chrome. then topcoated with anidize red. then a 80% clear coat. they looked real good when i took out of the oven. but about a week later i went into the shop and the fenders had spyder webbed on one side. you can see them but it is under the clear. o, i forgot i put an prizm additive in it to at 40 to 1 ratio. i preheated the oven to 425 deg. put the fenders in. then when it flowed out i cooled to 375 deg. for 15 mins. the clear i cured at 350 deg. for 15 mins. the only think i can figure is that the tops of the fenders was to close to the heating element. it was about 2 inchs away. i have had this problem before on some racing kart engine covers. please help me find out what i did wrong i cant afford to redo all these parts.

  • #2
    First off, welcome to the forum. Second, got any pictures of this spider webbing by any chance? From experience i can think of 2 things that may be happening. One, you put the chrome basecoat on too thick. When this happens, the surface of the chrome breaks and leaves a spider web look to it, especially on corners or on rounded edges. Another thing i can think or is under cure. If the powder is not fully cured, it is very brittle and if hit or banged could cause it to crack, sort of like a piece of glass would upon impact. I've had this problem when i first started with clear coats. If i did not cure the clear long enough, and went to screw the PCV valve into the valve cover, the clear would crack around that area. Also, with the translucent colors you really dont need to use a clear coat. The translucent color acts sort of as a clear coat. You may be putting so much coating on and not giving everything enough time to become fully cured leaving it brittle and thus cracking. Like i said post some pics up if you could and we'd all be willing to help you out. Good luck!

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    • #3
      I have had this same proplem before. I looked real good when I had first pulled it out, but than about a day or so later I saw these real fine cracks or spyder webing as you reffer to it. I just put it into the oven and cured it a little longer. Apperantly it wasn't completely cured, even though I had followed the time period for the curing.

      Here is a quote from Non-stick "ALL thermoset plastics (what you guys use at the moment) has a 100% overbake resistance built into the powder. This helps you in two ways. 1) if you are forgetful like me and let it set into the oven for 40 minutes at 330F, no need to worry. Just take it out like you normally would and nothing bad happened. Or 2) If there is a cold spot in the oven or something just hasn't flowed out enough, leave it in for longer. The parts that have melted and flowed already will not be harmed during the cure cycle on bit."

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      • #4
        Yep, if its brittle powder thats cracked, like the clear coat in my instance, just throw it in there and it should heal itself.

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        • #5
          Good work, gentlemen. I couldn't have said it any better myself. Classic case of undercure and quite possibly a thickness isssue but I wouldn't worry about that too much. What's happeneing here is that your powder hasn't "cross-linked" like it should. Therefore.... leaving you with two seperate coatings independantly of one another. When this happens, any minor flex will seperate the two and create a "spider web crack". Tiny at first and then eventually it will striate all over and chip off. Heat the part back up to at least give the effort to cure it and cross-link the coats into one another (crosslink just means that one powder will "meld" with another in a small way, flowing into the available pores,etc leaving one solid coating as opposed to two.). Don't be afraid to leave multiple coat processes in the oven a little longer to really give it time to cure out. Keep your temperatures on the lower side of the spectrum, but only the one setting is really necessary. say.... 375 for 20 minutes on a first coat, 375 for 20 minutes on a second, etc. If doing 3 coats ... lower is the key. After all... you'll be "re-curing" that same base coat 3 times in all, so that that into effect. Put it back in the oven.... cure it out and tell us what happened. Oh and by the way...... welcome to the family. As you can plainly see, each one of us is knowledgeable (even the newb's) and more than helpful. I hope you enjoy your time with us..... Russ

          p.s. - thanks again guys

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          • #6
            thanks

            thanks for the help i will put them back in the oven today and try it. the reason i put the clear on over the anidize red is when i put the prizm additive in it was rough. i used the clear to smooth it out. it looked real good for about a week then cracked. thanks again.

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            • #7
              i put the fenders back in this weekend. and heated back up to temp,and held for 30 mins. all the cracks disapered. thanks again.

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              • #8
                The true litmus test is if they return. The cracks dissapearing meant that it wasn't cured long enough (cured powder will not melt). Keep your eye on it for us and while you're at it.... how about some pics? The colour combination that you used sounds like it's got some nice hue's. (sorry.... I'm a huge picture hound,lol). I know I speak on behalf of the "gang" when I say I can't wait to see your results.... Russ

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