Painting Galvy Bulkhead advice

[supertreeman]

Swapping bulkheads in my 110 and new one is Galvy. It’s in primer stage now but lots of the imperfections from the galvanized are shown. Torn between trying to smooth these out before final paint or leaving as is. Final color is Alpine White so it should tone down some of the imperfections I’d think.

Curious what others have done?

 

[erover82]

I'd have started with a light sanding to remove high spots. At this point I'd sand, spray high build primer, and sand again. Repeat until you're satisfied. Then top coat.

 

[Napalm00]

I think you need to "pickle" the galv before you do any painting or it will flake off in about a year.

 

[erover82]

Pickling is an acid etch process used before galvanizing. Acid etch is also provided by etching primers. As long as the galvanizing is degreased, not powdering, and an etching non-alkyd primer is used, it should adhere well. Although if using a non-etching primer, you should certainly etch it priming.

 

[supertreeman]

Thanks for the suggestions. It’s being painted by a body shop not me and they used wherever was correct for Galvy. (I forget exactly but acid etching primer sounds right)

im not crazy about the imperfections so I think they need to go..

 

[LostChord]

I don't think the imperfections look that bad, but then again, my truck has quite the patina. Beauty is in the eye of the beholder I guess. I'd probably leave it and if anyone asked, explain that it is a galvy'd bulkead.

 

[Napalm00]

yep pickling /etching is what im referring to. I dont think that standard etching primer works on galv surfaces, its some secret sauce stuff

 

[rocky]

Depends on the quality of the ultimate finish.
I’d review your options with the shop, but you certainly want to level the depressions.

 

[CDN38]

After a light sanding, and knocking down any imperfections, galvanized metal should first be treated with PPG DX579. It's is a multi-purpose phosphoric acid based cleaner and pre-paint conditioner for most metals. It can be used to deep clean a metal surface prior to paint or to prepare a surface for a subsequent chemical conversion coating. Then PPG DX520 Metal conditioner. DX520 is a phosphoric acid based conditioner that will deposit a uniform layer of zinc phosphate on properly prepared galvanized and steel surfaces. DX520 is intended as the second step in a two step process, following DX579 application. THEN prime.

5 years on with this process and the paint is still perfect.

 

[erover82]

After a light sanding, and knocking down any imperfections, galvanized metal should first be treated with PPG DX579. It's is a multi-purpose phosphoric acid based cleaner and pre-paint conditioner for most metals. It can be used to deep clean a metal surface prior to paint or to prepare a surface for a subsequent chemical conversion coating. Then PPG DX520 Metal conditioner. DX520 is a phosphoric acid based conditioner that will deposit a uniform layer of zinc phosphate on properly prepared galvanized and steel surfaces. DX520 is intended as the second step in a two step process, following DX579 application. THEN prime.

5 years on with this process and the paint is still perfect.

Great option for non-etching base primers. However, not needed for self etching primers. From the PDF: "If the intended coating process includes spray applying Wash Primers (also known as etch primers or pretreatment coatings) to properly sanded and cleaned bare metal substrates, DX Metal Treatments in any combination are not required or advisable."

Your body shop should understand this stuff and advise you properly based on the paint systems they use.

 

[CDN38]

Great option for non-etching base primers. However, not needed for self etching primers. From the PDF: "If the intended coating process includes spray applying Wash Primers (also known as etch primers or pretreatment coatings) to properly sanded and cleaned bare metal substrates, DX Metal Treatments in any combination are not required or advisable."

Your body shop should understand this stuff and advise you properly based on the paint systems they use.

Ultimately, it's dependent on the type of paint being used as a finish. Prep, prime and paint should be completed by the same shop so the correct procedures, with the corresponding correct materials are used.

Wash Primers for Preparing HDG for Painting

Although brush-off blast cleaning is most commonly used for preparing and profiling hot-dip galvanized surfaces (HDG) for painting , ASTM D6386 , Practice for Preparation of Zinc (Hot-Dip Galvanized) Coated Iron and Steel Product and Hardware Surfaces for Painting , lists a wash primer treatment as…

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