Help with cracks?

[Guest]

Ive done powder before but only did clear coat for metal art products. Now i moved to japan and getting bigger than i can handle and comming up with porblems. Im only having problems with cracking in candy colors, blue/green


The above pics are muffler cutters, (its what they call them here in japan) I call them Muffler tips. We just got published in a few magazines as well and we put our stuff in the Tokyo auto salon, (the Cima show) of japan. these will be going out to customers so i cant have them cracking. Im a rookie and I would apreciate any help! The mufler tips are not going to be a problem cracking once its one the customers car, I just cant have it cracked when it gets to them. I also need help on the powder lingo, Gass out, Flow out-I know what this is but how do i know if its properly cured once flow out happens?

[JW450R1]

Re: Help with cracks?

welcome to the forum risingson
is the candy fully cured????

[Guest]

Re: Help with cracks?

flow out is when the powder melts (around 200 to 250 degrees or so) and fianl cure is when the part metal temp reaches the cure temp. for how ever many min. it takes to cure. All powders have different cure schedules.

I wonder if your base coat, if you have a base coat, was fully cured. If there is no base coat, I wonder if your candy coat is completely cured?

Do you check the parts with an IR gun for part metal temp.?

[Guest]

Re: Help with cracks?

Are those pieces chrome to begin with? Could be a problem with it and it's not the candies your putting over them. If your not sure you could run one through a cure cycle with nothing on it to see if it cracks as it cools.

By gas out I taking you mean out gas. This is where you put a part in the oven and run it through a cycle generaly fifty degrees higher than cure temp. This is to bring to the surface any contamination that might be in the pours of the metal. Like oil, grease, etc. This is mostly a problem with cast peices because they're porous. Most everybody outgasses at 450 degrees.

[Guest]

Re: Help with cracks?

Forgot to say Welcome to the forum!

[Guest]

Re: Help with cracks?

Welcome to the family and what type of clear is that ? Acrylic will crack if is baked at too high of a temperature of layed down too thick...

[Guest]

Re: Help with cracks?

Welcome to the family and what type of clear is that ? Acrylic will crack if is baked at too high of a temperature of layed down too thick...

Thats what im thinking.

[wiseguyz]

Re: Help with cracks?

Welcome to the forum. I'm going to venture a guess and say that you are undercuring. Coating directly over chrome should not be a problem. It looks to me like most of these are solid colors or candies without clear, so more than likely a single coat. From the photos, it doesn't appear that the coating is too thick. Make sure of your oven temperature, and more importantly, make sure your part reaches the proper cure temperature before starting your timer. When in doubt, cure a few minutes longer. Most powders have built-in overbake stability which will give you a margin of error before overcure would become an issue.

Best of luck.

[Guest]

Re: Help with cracks?

Thanks all for the warm welcome! Im going to work on the piece again with (all) Your advise and i will post the outcome, please stay tooned!