69red

What is the recommended way to paint over power coating.?
I just got my frame back from the powder coater. The frame was sandblasted and powder coated. There are more rust pits in the frame that show through the powder coating than I like. I am considering scuffing up the powder coating, filling the pits, and painting the frame.

DUB

I have no clue. i have been though this also....and now I know that if a part is rough looking and badly pitted that the power coating will not make it miraculously come out perfect like it was dipped. Maybe get a hold of the company that powder coated the frame and ask them what brand of powder coating powder they used and contact THAT company.

Keep in mind that IF you do not prep the inside of these pits and it is left shiny. The likelihood that what ever you put in them may not adhere. I doubt that chemical adhesion will work in this area....but you never know which is why you need to contact the company of the powder itself.

DUB

squared

I had the same issue with a motorcycle frame that I sent out to a powder coating shop in Cape Canaveral several years back. I normally like to treat steel with phosphoric acid to keep the surface rust down while the part's waiting to be coated, but it has to be rinsed off. I think what happened in this case was that the kid who did it didn't re-blast the part before he coated it. A couple years later, it was covered in surface spider cracks and rust pits. After that, I just started using two part epoxy on my bike restorations, that way I control the process. If it was me, I would try epoxy with some marine based non-talc based filler (West System) to thicken it up, let it cure, then come back a few days later and see if you can scrape it off with anything other than a metal scraper. Don't use a polyester based resin filler, it probably won't stick...epoxy sticks to almost anything including jet-ski hulls that see a lot of abuse..

tmryann

I would wetsand the surface or apply adhesion promoter so that the paint will stick really well.

DUB

But what about deep pits where he cannot sand it like I mentioned???? Which is why it is being filled in...which can mean this could be a total waste of time if where he can not get the powder coat prepped ...the filler pops out.

bazza77

I had to modify a powder coated bracket with some welding , the heat obviously melted away the black powder coating , so I put it in my sandblasting booth and hit it , managed to clean back the fuzzy edges of the damaged powder coat and feather it down enough so I couldn't feel an edge. Blasted all of it to get a profile on the rest of it , Primed & Painted all of it with a 2 pack , which is still holding on after about a year . Bracket is under the car so its good enough for me .

Obviously a frame is a bit bigger , but building a cocoon in a shed just around the damaged areas may be possible , used to do blasting for a living , we would spend hours building a plastic cocoon for one small blast job (in a working power station , no media overspray allowed !) fun times !!!!

squared

I didn't say it but I kind of thought it was a given that he had to be able to scuff up the pit which is a problem. I think that letting it set up and then going back and trying to pop it out might work but I don't know it depends on how bad it's pitted I guess. Spot blasting it may work with a small blaster

DUB

I agree with using media and a small blaster to etch the powder coat in the pitted areas.

Like I previously wrote ...I feel it would be wise for him to call the company of the powder coat that was used and talk with them. I do not know if the actual powder coat is solvent sensitive to a point where applying a filler directly on it could allow that solvent it the filler to etch into it or not on the molecular level.

That is why unless I know if a surface can accept a product being applied on it that can chemically bond to it and not need mechanical adhesion I would always abrade it in some manner.....which it seems we all agree on that aspect.

DUB

csherman

my powder coater will resand pitted parts and recoat them
I took them several really bad wheels
the insides were severely pitted
He blasted them
coated them
Resanded them and recoated them
They are really nice - not perfect but nice.
I will continue to use this process

csherman

To answer your question - the answer is yes - you can sand it and body work over the top of it - you can also refinish over the top of it.....
I scuff the surface thoroughly

DUB

Thanks for letting us know. I figured it could be sanded and painted....even though I have not yet needed to do that yet....which also confirms what previous members stated also.

DUB