Painting over Zinc Primer

[msd58]

I just finished priming my B3 lower unit with green Moeller Zinc primer. I plan on painting the black over the weekend. Does the zinc primer need to me "roughed up" for a mechanical bond? Can I paint over it as is?

 

[GA_Boater]

Zincs shouldn't be painted. They are sacrificial, meaning the way they work is the zinc gives up it's life to protect the aluminum parts of the motor. Painting he zinc could be harmful to the motor. Leave them bare.

If you primered them, clean the primer off.

 

[Captain Ollie West]

I think the OP is asking if he needs to scuff the zinc based primer on his lower unit prior to painting it black ... I am curious as I will soon be doing the same thing. (painting over zinc primer).

 

[fhhuber]

Primer's purpose is helping the color coat(s) stick.
Zinc in the primer is there to aid in corrosion resistance.

Pretty commonly used in the US Navy... we had several primers that had zinc. We never left the primer as the final coat, whether it be on the hull, piping, airplane... whatever. (Yep at a certain point in painting a F-18, its Zinc Chromate green)

Just the name "primer" points out its intended to have other paint applied after.

You just need to dust off the primer with a clean dry rag if you haven't been handling the part. if you've been handling it you should use a solvent that will not attack the primer to get the oils from your hands off of the paint.

Look on the can directions or get the MSDS from the store where you bought the paint. the paint maker will tell you what solvent to use if you need to degrease the primer.

Handle the parts with nytrile or other chem resistant gloves between coats and avoid needing the solvent...

 

[Scott Danforth]

I usually top coat shortly after primer dries to get good solvent adhesion. if you wait too long, you will need to lightly sand to get adhesion.

 

[msd58]

I usually top coat shortly after primer dries to get good solvent adhesion. if you wait too long, you will need to lightly sand to get adhesion.

Its not likely I will get to paint top coat until tonight. Last coat of zinc primer went one last night around 10PM

 

[GA_Boater]

Sorry if I mislead you, msd58. It was late and I'm not used to seeing zinc primer. If I had read zinc chromate primer, I would have understood. :embarassed:

Carry on with the advice the guys gave.

 

[gm280]

Sound like he used zinc chromate type primer and wants to know if he should shoot top coat paint or what. I say the zinc chromate primer needs to be primed with a compatible primer before shooting any top coat paint. The usual setup is bare aluminum then zinc chromate then regular primer and then top coat paint. That is usually how aluminum metals are done. JMHO!

 

[msd58]

Sound like he used zinc chromate type primer and wants to know if he should shoot top coat paint or what. I say the zinc chromate primer needs to be primed with a compatible primer before shooting any top coat paint. The usual setup is bare aluminum then zinc chromate then regular primer and then top coat paint. That is usually how aluminum metals are done. JMHO!

What is the correct and compatible primer?

 

[Scott Danforth]

if your using the Moeller paints, simply scuff and paint. or put a second coat as a tie coat and then paint your black

if your spraying with PPG paints, prime with the appropriate PPG primer

 

[harleyman1975]

Scuff with a red scotch brite or 600 grit paper. Yes you need mechanical adhesion at this point.

 

[gm280]

What is the correct and compatible primer?

I use PPG 2k primers and then Shop Line top coats followed with PPG clear coats. JP202 is a good primer to go with. It will adhere to the zinc chromate and offer a very good surface for the top coat. Just remember, if there are any flaws in the primer coat, it will show in the finish as well. So make sure your primer is exactly like you want it before shooting the top coat(s). JMHO!

 

[JimS123]

You should have topcoated within 1 hour of applying the "zinc". Since you didn't, wait 7 days, scarify with a fine sandopaper, and then topcoat, with each successive coat 1 hour apart.