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Preparing newly galvanized parts for painting

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Troll Hunter
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Preparing newly galvanized parts for painting

#1 Post by Troll Hunter » Wed Dec 06, 2017 10:12 pm

In UK, the accepted treatment for newly galvanized parts, generally complete chassis, is to treat them with a chemical solution known as T-wash, produced by WM Barr. I've been unable to identify an equivalent treatment here. Please, what is used to treat freshly hot dip galvanized components before painting? Many thanks, in advance, for any and all suggestions.

Mike

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bsa_m21
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Re: Preparing newly galvanized parts for painting

#2 Post by bsa_m21 » Wed Dec 06, 2017 11:13 pm

You can download the product specs and safety data here:

https://www.crowntrade.co.uk/product/ex ... gs-t-wash/

The safety data sheet (similar to our MSDS) lists the material composition. Seems it is an etching primer. You should be able to find something similar from an industrial paint supplier. More into on painting over galvanizing is available here:

http://daamgalvanizing.com/wp-content/u ... el2011.pdf

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island dormy
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Re: Preparing newly galvanized parts for painting

#3 Post by island dormy » Thu Dec 07, 2017 8:59 am

Hi Mike

Fresh galvanized metal has kind of a oily finish so what you can do is first wire brush the metal (to etch it a bit so the paint sticks) then wash down with pure white vinegar (vinegar is a acid) rinse with clean water then use a primer made for galvanized metal then top coat with the finish coat.
I have used this method with no problems.

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Troll Hunter
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Re: Preparing newly galvanized parts for painting

#4 Post by Troll Hunter » Sat Dec 09, 2017 11:39 am

Many thanks, both, for the replies and links. I've sent Crown an e-mail to ask if their products are available over here, and ann e-mail to Daam to ask if they can recommend a specific product(s).

I've read up on the different requirements for the various conditions of galvanized steel, but I'm really stuck on getting actual brand names of suitable etch primer. The American Galvanizers Association (http://www.galvanizeit.org) is a great source of information, but it stops short of recommending actual products.

After using vinegar as an etch solution what primer do you use, island dormy? Have you had any of the painted galvanized items exposed to road salt, and have you had any paint failures? Since I'm doing a complete rebuild I don't want to have to come back in a couple of years time to re-do anything.

Mike

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Re: Preparing newly galvanized parts for painting

#5 Post by island dormy » Mon Dec 11, 2017 7:08 pm

Hi mike

I just used galvanizing spray primer in a spray can or paint on galvanized metal primer from the hard ware store. Then simply painted it with the top coat I was using. Usually tremclad oil based paint .

I have not subjected the galvanized painting I did to road salt but would think that it would be okay once the top coat was applied?
I do know that if you simply paint over galvanizing with out doing any cleaning and priming before hand it will peal in great big chunks.

The other thing I know is galvanized primer is very $$ and it is getting hard to find.

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tony
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Re: Preparing newly galvanized parts for painting

#6 Post by tony » Tue Dec 12, 2017 9:55 am

Ive had good luck with Endura primer and paint, it sticks to galvanized metal as well as aluminum and steel. No harder to work with as some people had led me to believe
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Troll Hunter
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Re: Preparing newly galvanized parts for painting

#7 Post by Troll Hunter » Mon Dec 18, 2017 7:08 pm

I have not had a reply from Crown, not even an acknowledgement, but this is the reply I received from Daam:

Quote:
We have never used the etch/wash primer system when painting over galvanized steel. Although etch/wash system have been effective, our preference and our past use has been to light sandblast the freshly galvanized coating to give it a slight profile and remove any surface oxidation, then we apply a coat of Devoe Devran 303 primer, followed by two top coats of Endura EX/2C Urethane
Unquote

Perhaps I'll have to rethink my painting program, but I don't really want to get into more blasting, of any type. It's messy if I do it myself, and expensive if I pay for it to be done. :( . I am, as they say, reviewing my options!

Mike

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CDN38
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Re: Preparing newly galvanized parts for painting

#8 Post by CDN38 » Tue Dec 19, 2017 8:56 am

T wash is the go to fo prepping galvanized steel for paint or coating, http://www.decoratingdirect.co.uk/viewprod/t/TORTWASH/ However, it's not available here. Best option here is as follows:

There are 2 PPG products that work together specifically for prepping galvanized metals for paint. First, you need to file and sand the galvanized surface to remove any excess zinc. Apply DX579 a multi-purpose phosphoric acid based cleaner and prepaint 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 coating. Then apply DX520, a phosphoric acid based coating chemical that will produce a zinc phosphate coating on galvanized or steel surfaces. DX520 contains a small amount of detergent which aids in the removal of light soils and oils and promotes the formation of a uniform zinc phosphate coating. DX520 is pale green in color and may turn darker over time.

These are applied with a scotchbrite pad and rinsed with water after. The treated metal should be painted within 24 hours of prep.

I used this process on both my side frames 2 years ago, the paint has had no issues with adhesion.

Troll Hunter
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Re: Preparing newly galvanized parts for painting

#9 Post by Troll Hunter » Fri Dec 22, 2017 6:57 am

Thanks for the detailed info, CDN38. I've been looking for T-wash, or the equivalent that's available this side of the Atlantic, and I think you've just pointed me in the right direction.

Mike

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