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Powder Coat blisters! HELP PLEASE!

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bdeihl570
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Powder Coat blisters! HELP PLEASE!

Postby bdeihl570 » Thu Nov 05, 2015 11:59 am

Guys,

I'm fairly new still to all of this plasma cutting, and let me start off by saying that I have never powder coated anything in my life. I am asking about issues I'm having with the powder coating from the man that I get my powder coating done by. Has anyone ever had a problem with the already baked powder blistering up and flaking off, like maybe a week or two weeks after the piece was coated? I don't understand it. My last trip to the powder coater I took about 50 pieces. Depending on the piece, there were 6 colors he had to spray. about 6 pieces were a burgandy pearl color. About 12 pieces were plain gloss white. Some were black and silver vein. Some were Gold Pewter color. About 30 pieces had started to blister in just small areas (in between 1/2" and 1"). Here is our process. We use Hot Rolled Steel. We cut out whatever images we need and then those pieces go into a vinegar bath for about 12 hours to remove the mill scale. We pull them out one at a time and thoroughly rinse the pieces of. We immediately dry the piece with shop air which is very dry air. After drying, we may let the piece sit there on the table until we are ready to work on it or we may get started right away on it. We remove all sharp edges and buff both sides of the piece with a 3M paint removal pad, which removes any remaining mill scale and also leaves a slight profile in the surface of the piece. We then place it to the side to wait until we have enough pieces to take to the powder coater, which is usually only a day or two.
Now the coating blisters didn't all happen in the same location. Some areas blistered right at the edge of the piece, and some blistered right in the middle of the piece, no near an edge or a cut out. Can anyone explain what is going on? I am losing a lot of money in repairs and sales! Thank you in advance!

Brandon Deihl

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Re: Powder Coat blisters! HELP PLEASE!

Postby acourtjester » Thu Nov 05, 2015 12:49 pm

It sounds like contamination on the surface of the metal. Can you see any rust where if flakes off or is it clean?
It may happen because of how the metal is handle before powder is applied, like other costing the surface needs to be clean or it will not stick.
maybe he has water in his air supply and it is transferred to the metal as it is applied then it boils when cooked.
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bdeihl570
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Re: Powder Coat blisters! HELP PLEASE!

Postby bdeihl570 » Thu Nov 05, 2015 1:45 pm

acourtjester,

I am thinking the same thing. I appreciate the reply. I have to go talk to my powder coater today about all of this.

Brandon

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Re: Powder Coat blisters! HELP PLEASE!

Postby TMC » Thu Nov 05, 2015 3:25 pm

find out how they are prepping your pieces before they powder them. They should be at least sand blasting them and shooting the powder as soon as finished blasting. Also take note when you visit them to see if they use latex type gloves when handling pieces. If after prepping and they handle with bare hands the oils from fingers will also cause issues. If you take them any aluminum they should be out gassing the piece first.
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Re: Powder Coat blisters! HELP PLEASE!

Postby Shane Warnick » Thu Nov 05, 2015 3:34 pm

I was thinking contamination from fingers as well. I think you are getting oil onto the pieces somehow before they are coated. Several places it could be coming from, could be shop air on your end, shop air on his end (is he sand blasting them, if so they usually hit them with the air before going into the booth just to make sure there isn't any sand hanging on), could be contaminated air on his end coming out of the gun when he is spraying, or could be your fingerprints and he isn't prepping before coating, could be their fingerprints after they prep going into the booth, or..........

Bottom line, I think you are getting oil onto the pieces either off of fingers or aerosolized from some other source. His coating is failing, he should stand behind it and make it right, in my opinion.

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Re: Powder Coat blisters! HELP PLEASE!

Postby comeoutswingin » Thu Nov 05, 2015 4:46 pm

I fought issues with contamination when I first started. Sometimes I still get issues. One thing I stopped doing, no matter the material used is grinding and cleaning dross off before I degreased, rinsed, and degreased, and rinsed, and degreased and rinsed (getting the idea>). THEN clean the dross, wirewheel/grind, then rinse again and then powdercoat. That gives me pretty good luck.

same thing with sandblasting, before I blast I always wash and wash. Blasting seems to embed oil and junk that you couldn't even see to begin with.
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Re: Powder Coat blisters! HELP PLEASE!

Postby little blue choo » Thu Nov 05, 2015 8:03 pm

I have been having my powder coating done my Advanced powder coating in Cherryville NC for over 10 years and have never had a problem. I build trackless trains. I take the metal as it comes from my supplier, cut it, weld it and send it to the powder coated with all the oil that came on it. They pressure wash it, spray it and bake it and I have never had a problem. They have done all my frames and roof mounts for 10 years with no problems. I wonder why so many have had problems and I haven't and I do no cleaning of the metal at all. I am going to talk to my powder coater tomorrow and see what he thinks.

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Re: Powder Coat blisters! HELP PLEASE!

Postby Gamelord » Thu Nov 05, 2015 9:35 pm

My guess would be outgassing that is causing it. Could be from the Vinegar, could be from the 3m sanding, could be from residue mill scale.

All of this should be taken care of when your powdercoater does his prep work though....

The pieces need to be thoroughly cleaned, de-greased and sand blasted to remove any residue or contaminates. If not done properly you will have issues like what you are explaining. Even bare raw metal from a yard should have no issues after powdercoating if the powder shop does it right.

I would take your next batch to another shop just to see how it comes out. Even if it costs a little more, you will probably save more over the long run with returns and re-do's.
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Re: Powder Coat blisters! HELP PLEASE!

Postby little blue choo » Thu Nov 05, 2015 10:00 pm

Brandon, just wondering what your powder coater had to say about your peeling problem.

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bdeihl570
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Re: Powder Coat blisters! HELP PLEASE!

Postby bdeihl570 » Fri Feb 12, 2016 5:51 pm

Sorry I havent replied back lately. We have been spray painting almost everything lately so I havent dealt with the powder coating side og it much. My powder coater has came up with all kinds of excuses. He claimed it must be metal contamination. We don't know and can't prove anything so we are about to venture out and start powder coating ourselves. Thank you all for your suggestions and thoughts. I really appreciate it.

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Re: Powder Coat blisters! HELP PLEASE!

Postby james.davis » Sat Feb 13, 2016 8:07 am

Rick,
You must be the hit of the neighborhood with the kids :)
Nice train.
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Re: Powder Coat blisters! HELP PLEASE!

Postby tjenus » Mon Oct 03, 2016 10:59 am

Gamelord wrote:My guess would be outgassing that is causing it. Could be from the Vinegar, could be from the 3m sanding, could be from residue mill scale.

All of this should be taken care of when your powdercoater does his prep work though....

The pieces need to be thoroughly cleaned, de-greased and sand blasted to remove any residue or contaminates. If not done properly you will have issues like what you are explaining. Even bare raw metal from a yard should have no issues after powdercoating if the powder shop does it right.

I would take your next batch to another shop just to see how it comes out. Even if it costs a little more, you will probably save more over the long run with returns and re-do's.



I Agree, outgassing will cause blisters, to many thinks to list on what can cause that,
I powder coated in a production shop for years, We used a 5 stage cleaning system, Caustic, Acid, Phosfate , and lots of water to rinse and heat to dry, Preheat all cast items before coating to reduce outgassing,

I preferred not to have any parts prepped, Chemical wise, grind what needs done and drop it off, we will clean it, also would not Blast Greasy parts, Always would clean them first then blast and send them through the cleaners the day of coating, never before, only had a few come backs in 5 years, normally it was always just bad prep, 95% prep, 5% coating, thanks KH
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Re: Powder Coat blisters! HELP PLEASE!

Postby Unvevo » Fri Oct 14, 2016 8:33 pm

You can also get star burst from built up current. I was having this problem with my cheaper eastwood gun and had to add a 10' grounding rod right next to my booth. I no longer have this issue. Just throwing this in here incase out gassing was not the problem.


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