Am I not curing enough?

[Guest]

Getting away from fancy two tones and big items and going back to basics for a minutes.

I've done a few parts in mirror colors that seem to have either never gained full gloss or lost some gloss from curing. The other issue is that sometimes parts are easily scratched, not something that should be happening with powder coating. If I just run a rag across the part a few hours or even days later just to clean it up, I will get some swirl marks and light surface scratches. I suspect I'm not following the correct curing schedule.

I've heating the oven up to 400F, sticking the part in and checking every couple of minutes to check part temperature depending on size. Most small brackets seem to reach 400F in about 5 minutes, valve covers in about 10 minutes. I then start the timer and cure for 10 minutes or whatever the powder calls for. After 10 minutes I turn the oven off and crack the door while the part sits in the rack. After about 5-10-15 minutes I pull it out.

Am I doing something wrong? The mirrors look great until any sort of intense light like a flash light, headlight, or just really bright sun hits it. Then you can see the small scratches and dull looking almost gray spotted finish.

Any suggestions? Thanks!

[Guest]

Re: Am I not curing enough?

This is really frustrating... I went ahead and stuck the part back in the oven for an additional 5 minutes and now it has super tiny almost invisible pin holes in it. Surface is still not any stronger, scratches very easily and dulls by just wiping it off with a micro fiber towel. Is this related to curing? Can it be too much powder or not enough powder? I need to find a way to read thickness, I'm still not sure how much powder is the right amount so I always either put down way too much powder or a coat that's too thin to even cover the surface...

[Guest]

Re: Am I not curing enough?

I have noticed this wipe mark issue on things I do. Mostly black, course thats mostly what I do right now. I know I'm curing right. I check my part temp every five minutes. I use a timer. And cure for the proper amount of time again using a timer after the part has reach temp. Checking temp with a IR gun. I don't have a orange peel issue so I'm guessing theres not a coating amount issue.

Harley

[Guest]

Re: Am I not curing enough?

I have noticed this wipe mark issue on things I do. Mostly black, course thats mostly what I do right now. I know I'm curing right. I check my part temp every five minutes. I use a timer. And cure for the proper amount of time again using a timer after the part has reach temp. Checking temp with a IR gun. I don't have a orange peel issue so I'm guessing theres not a coating amount issue.

Harley

I'm only having this problem with Mirror Black and Mirror Red. Everything else seems fine, especially colors with low gloss.

I do the same thing, check the part every few minutes. Usually I will start the timer as soon as I see a reading of 385+, then check again in 5 minutes to make sure it didn't go over... they usually stay around 395-405.

[Guest]

Re: Am I not curing enough?

Do those pinholes look like tiny little specs of silver? As the powder cures air and gases are released. If you're heating the part up to cure temp to quick the powder is not in the flow stage long enough for those little pinholes to repair themselves. This typically happens with higher film builds. You could try a litle less powder and cure at a lower temp,longer time.

That's exactly what they look like. They look like silver dust I could just wipe off, but I can't. This brings up the next question, is it better to do multiple light coats or one heavy coat?

[Guest]

Re: Am I not curing enough?

Juan]

I have noticed this wipe mark issue on things I do. Mostly black, course thats mostly what I do right now. I know I'm curing right. I check my part temp every five minutes. I use a timer. And cure for the proper amount of time again using a timer after the part has reach temp. Checking temp with a IR gun. I don't have a orange peel issue so I'm guessing theres not a coating amount issue.

Harley

I'm only having this problem with Mirror Black and Mirror Red. Everything else seems fine, especially colors with low gloss.

I do the same thing, check the part every few minutes. Usually I will start the timer as soon as I see a reading of 385+, then check again in 5 minutes to make sure it didn't go over... they usually stay around 395-405.

It's weird for me cause I check my parts temp and their 400 plus everytime that I set the timer. I haven't done mirrors yet hoping to do Mirror black this weekend. I pull my parts to cool for most some I have propped the door open.
Juan sorry about honing in on your thread but since I have the same issue on some parts I have done I thought I'd jump in. My bad if I'm being rude. I did some more glosss black pieces yesterday and I'm going to check them tonight for the scratches. I monitored my parts closer that time.

Harley

[Guest]

Re: Am I not curing enough?

Okay I checked my stuff I did and as much as it pained me I found a spot I think will be inconspicous and wiped like crazy. And no scratches. Damm it that makes harleydad right again. Actually I will give some credit to the new oven and the new PID and contractor in the small oven. And maybe a bit to monitoring closer and using the timer to my advantage. I cross my fingers it stays that way and it seems I'm getting better at this. I also did the MEK test. I soak a rag in MEK and wiped several times across the black piece and no black on the rag. Probably to much MEK but I wasn't sure how much so I just poured. Then I have read from swipe it to rub it so I went for it.

Harley

[Guest]

Re: Am I not curing enough?

"I've heating the oven up to 400F, sticking the part in"

You might want to try putting the part in the oven first then bring it up to temp. I find I get better gloss this way.
Like HD said you could be bringing it up to temp to quick. Not giving it enough time to flow properly.

[Guest]

Re: Am I not curing enough?

Juan have you tried anything to see if your problem is gone?

Harley