Powder coating something zine plated?

[lfsracing]

Just wondering if you have to remove the zinc plating before coating it? Sucky part is I just finished blasting all my parts and my brother just asked me to do these 2 hooks for him and I told him the coating probably needs removed first. I don't feel like taking the stuff back to work as he needs it for tomorrow. Just wondering if I sand it with sand paper if that will be OK enough so I don't have to sand blast them?

Any info would be great.
Lorenzo

[jtagger19]

it should be blasted
but if you are in a run sand it with 80-120 grit and it will be good to go.
it would still need to be cleaned.
i did it with some VW parts and never had any problems with them .

[lfsracing]

Yeah that's what I just did. We just used 100 grit sandpaper and it came off really easy I figured it would as it coudln't of been thick to begin with. I will get them cleaned up shortly and I have to PC some of my stuff so figured I can do them for him.
Lorenzo

[bzer1]

Shouldn't be a problem. I coat over zinc plating quite a bit and have not had a problem yet. Like any other part, just make sure that there is no undermining of the present coating and it should be just fine.

[seanc]

Raw zinc is a great base for powder coat

Most zinc parts though, are chromated too, and most chromates don't tolerate high temperatures.

If these are older parts, the chromate may be gone or partially worn off already. Where it's gone you're likely to have zinc oxide. Powder won't stick well to that, and weak chromates may lift.

Chromates & oxides will come of with a blasting. An easier way is to strip it in @5-10% muriatic acid. This also activates the zinc, which is best for powder coating.

Of course, you can strip the zinc completely in acid too, if you want it back to raw steel.

[Banditperformance]

YUp, Miriatic acid. Takes the zinc and gavanizing right off. Just pour the acid in a bucket, dilute with water. Then dip parts.

[FSTFBDY]

Originally Posted by seanc

Raw zinc is a great base for powder coat

Most zinc parts though, are chromated too, and most chromates don't tolerate high temperatures.

If these are older parts, the chromate may be gone or partially worn off already. Where it's gone you're likely to have zinc oxide. Powder won't stick well to that, and weak chromates may lift.

Chromates & oxides will come of with a blasting. An easier way is to strip it in @5-10% muriatic acid. This also activates the zinc, which is best for powder coating.

Of course, you can strip the zinc completely in acid too, if you want it back to raw steel.

+1 for everything he said. I manufacture some brake parts and ZINC em and then powder coat em. being under the car I like the added fact they have a good zinc coating on em also..