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clear powder over patina...

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Cracker Red
Posts: 152
Joined: Sat May 03, 2014 3:24 pm

clear powder over patina...

Postby Cracker Red » Wed Nov 23, 2016 2:56 pm

I want to start powdercoating clear over my steel pieces. Every time I send one to the powdercoater it drastically changes color from deep bronze to a greenish yellow.

I spoke with Bill yesterday who told me it was cooking for too long. Followed prismatic powders directions to a "T" for clear today (400deg PMT for 10 mins) and it was again yellow green coming out of the oven.


I'm worried to use spray clear on outdoor steel pieces....Ive not had luck getting the rust protection that powdercoating offers....always seems to spider rust from the edges in 4-5 months. I can't sell items to customers I know will rust on them....can someone point me to what I'm doing wrong?

comeoutswingin
Elite Contributing Member
Elite Contributing Member
Posts: 122
Joined: Fri Oct 16, 2009 10:34 pm

Re: clear powder over patina...

Postby comeoutswingin » Wed Nov 23, 2016 2:58 pm

Its cooking too hot. I discovered this issue when I was still doing the patina stuff.. I cured at 250 degrees.. which is under curing, but for these, durability doesn't need to be the same as say a bumper..
5x10 LDR

Cracker Red
Posts: 152
Joined: Sat May 03, 2014 3:24 pm

Re: clear powder over patina...

Postby Cracker Red » Wed Nov 23, 2016 9:48 pm

I'll give it a try. I have a duel use booth (powder and clear/dye) but never have luck with clear coating steel pieces....all end up rusting along the edges no matter what I do. Being that I'm in FL I battle the climate 10 months a year.


How long did you cook it for?

blackandtan
Posts: 199
Joined: Thu Jul 18, 2013 3:05 pm

Re: clear powder over patina...

Postby blackandtan » Wed Nov 23, 2016 11:15 pm

I guess I'm not the only one in Florida fighting this issue with rust. I was wandering if using clear powder would help with that.

Cracker Red wrote:I'll give it a try. I have a duel use booth (powder and clear/dye) but never have luck with clear coating steel pieces....all end up rusting along the edges no matter what I do. Being that I'm in FL I battle the climate 10 months a year.


How long did you cook it for?

comeoutswingin
Elite Contributing Member
Elite Contributing Member
Posts: 122
Joined: Fri Oct 16, 2009 10:34 pm

Re: clear powder over patina...

Postby comeoutswingin » Thu Nov 24, 2016 3:33 am

The edges are probably rusting from edge pull.. basically the powder doesn't adhere to the tiny sharp edges of the steel, as it cures it pulls away even more. I get it a lot on black powder.. best solution? sand the edges until they're smooth and dull. (lots of work and on artwork, pretty much impossible.)
5x10 LDR

Cracker Red
Posts: 152
Joined: Sat May 03, 2014 3:24 pm

Re: clear powder over patina...

Postby Cracker Red » Thu Nov 24, 2016 9:33 pm

It's not rusting with powder on the edges....only with clear coating. No problem with clear power, aside from the color change with patina...

GDS Metal Worx
Posts: 156
Joined: Tue Dec 18, 2012 9:33 am
Location: Lexington, KY
Contact:

Re: clear powder over patina...

Postby GDS Metal Worx » Fri Nov 25, 2016 8:04 am

Columbia coatings has a low temp cure clear. Try that out. I use super durable wet clear from columbia and have had no issues. I also cure at a lower temp, around 350, and bake it just a little longer.

motoguy
Posts: 931
Joined: Tue Aug 25, 2015 12:05 pm
Location: Central MO, USA

Re: clear powder over patina...

Postby motoguy » Sat Apr 29, 2017 3:42 am

I finally got my powder setup going, and powdered my first parts today. I ran into the same issue with a patina test piece. Went in looking normal, came out blown all to hell! Ugly gold/yellow/green looking thing.

I did some digging on Bill's site, and found a FAQ where he basically suggest minimizing heat exposure. Don't heat-soak the part. Don't run full cure time. Don't let the part cure in the oven. He suggests pulling the part as soon as the powder flows.

I made a 2nd piece, and tried his suggestions. I pre-heated the oven to 400 degrees. Coated the part, stuck it in the oven. I checked at 3 minutes, and it had flowed out nicely. Pulled the part, let it cool, and have the BEST looking clear coat on a patina part that I've ever had. I don't -think- there was any change in the patina, however I'm going to run a couple more at 2 minutes and 2:30 to see if there's a sweet spot.

BTW...my Sharpe Finex 1000 gun arrived just the other day. After today, I don't know why I would ever want to spray paint again!
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