scratches

[coleman5]

im geting scratches from handaling parts after i powder coat them like if i wipe lint off or rub my finger acrost the surface.
am i not curing longenuf or do's the powder have to set for so many hours ?
i powder then in the oven at 400 i dont start the timer until the powder starts to melt and t6hen cure for 30 min.
its perl black i have the problem with
or is it i notise it more with black ?

[pickleboy]

Re: scratches

it will be more noticeable on dark colors. most likely from your process description it is an undercure problem. when you powder and put it in the oven most powders will flow around 300-350 degrees. even at 30 minutes it is most likely is not reaching the required 400 degrees for 20 minutes that is needed for full cure. the best thing to do is get a laser thermometr to check the part temp. when the part hits the cure temp then and only then do you start the clock for cure time. hope this helps bro.

[mtnbiker]

Re: scratches

I have found scratches from under cure. But at 30 min after flow out.. doesnt sound like it.

Most powders dont require 30 min after flow out. That seems awfully long.

Most are in the 10-20 min range. I RARELY have a part in the oven for more than 30 min TOTAL.

[BigDog]

Re: scratches

it will be more noticeable on dark colors. most likely from your process description it is an undercure problem. when you powder and put it in the oven most powders will flow around 300-350 degrees. even at 30 minutes it is most likely is not reaching the required 400 degrees for 20 minutes that is needed for full cure. the best thing to do is get a laser thermometr to check the part temp. when the part hits the cure temp then and only then do you start the clock for cure time. hope this helps bro.

I had the same problems and i got the laser witch worked great, thank you for the post even know i didn't ask i found it to be very useful.

[hvac36]

Re: scratches

I agree with pickleboy, get the Lazer therm. Look at this way if you heat at small part say a door handle that will get to 400 with in mins, but lets say your doing an engine block ( old cast iron block) that will take upwards of 45 mins to an hour to hit temp.. So just because the powder is melting does not mean its up to temp.. The Powder on teh block will start to melt after 20 mins in teh oven but the block is a long way from 400 degrees..
Also instead of using teh max temp to get the part in and out of teh oven the fastest, lower the temp and use a longer cure time, this seems to help with those dark colors.
If a color requires say 400 for 15 mins, do 375 for 25 mins.. Will also do a more even of a flow out of the powder..

Jim S...