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How to re-finish Galvanized Metal Shelving/Racks for retail use?

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RFQ: Good day,

We have shelves that are getting rusty. Some are steel and some are galvanized. The steel ones has been painted. Is there a place that can re-galvanize all the shelves and get rid of the rust?

Regards,
Olga

Olga Neuhoff
Manager - Hoedspruit - South Africa - Limpopo
June 17, 2022

              privately respond to this RFQ   ^
            Ed. note: As always, gentle readers: technical replies in public please; commercial replies in private (huh? why?)


A. Re-galvanizing.
Galvanizing is an alloying reaction between steel (iron) and molten zinc. It forms zinc-iron alloys on the surface of the steel. Presenting zinc (as in old galvanizing) to the molten zinc won't allow this alloy to form, so the old galv must be removed. Fortunately that can be done in acid, and a dip in acid is one of the several dips that steel undergoes in the process of galvanizing. Unfortunately that zinc consumes far more acid that just cleaning steel does, so most galvanizers charge extra for removing residual old galvanizing. But it can be and often is done.
Painted steel is another problem. The paint acts as a masking to prevent the acid cleaning the steel prior to galvanizing, so it has to be removed. The acid doesn't remove it so some other method is required. Usually shotblasting is the method. Grinding with an angle grinder or sander is rarely good enough.
Other than these two issues, both your old galvanized and old painted shelves should be able to be galvanized. But beware of they are made from pre-galvanized sheetmetal. That has been galvanized in a different process more like a printing press (continuous strip round rollers), and general batch based hot dip galv can cause distortion in very thin sheetmetal.

Update: Most Galvanizers in SA could do this, call your nearest and ask them. For a list of most of them see the association website here:
https://www.hdgasa.org.za/galvanizing-members/

They will charge something to remove all traces of old galvanizing, then start with the clean steel and re-galvanize. For painted ones, shot blasting might be required for paint removal then re-galvanizing.

geoff_crowley
Geoff Crowley
Crithwood Ltd.
supporting advertiser
Bathgate, Scotland, UK
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Hello Ted,

Thank you for the information on removing acid stains from galvanized metal.

We have a very nice butcher block table, with a galvanized shelf below the table top.

I placed a set of jumper cables, in a plastic bag, put them on the shelf and forgot about them. Yesterday, I was cleaning the table outside, when I noticed that the plastic bag had leaked and the battery acid caused large stains on the galvanized shelf. I poured white vinegar on the shelf, rubbed the surface with wet rags and rinsed the galvanized top. WHAT CAN i DO TO MAKE THE METAL surface more presentable? Many thanks in advance for your help. Cheers, David

David Kropelnicki
- Casablanca Chile
July 3, 2022


A. Hi David. Galvanizing is zinc, which dissolves quite instantly in strong acids. I don't have a pic to fully understand your situation, but I would think the acid pretty much destroyed the galvanizing. So I would suggest using undiluted vinegar or an even stronger acid to remove the rest of the galvanizing, then neutralize it with baking soda, get it down to nice clean steel and clear coat it.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey


July 4, 2022

thumbs up sign Hello Ted,

Many thanks for your reply to my galvanized table shelf mess!

I will finish the shelf today.

All the best ,

David

David Kropelnicki
- Casablanca, Chile




Closely related Q&A's, oldest first:

Q. Hi,

I am opening up a children's & teen's clothing store. I have purchased about 26 rolling Rack/shelves that were previously used in an Old Navy store. The main body of the racks are made of a galvanized steel/metal. They have welding points on all the joints that look like they have been spray painted to cover the weld areas. The metal itself is not rusty (a few spots here & there) is just looks very beaten up & used. I was wondering what I could do to "refinish" them. The are somewhat dirty as well from sitting in a warehouse for quite some time.

Should I clean them? What should I use? Should I spray paint them with a metal paint?
In my dream of dreams the racks would have a brushed finish to them rather than the galvanized look is there something I could use to achieve this sort of finish?
As well whatever I do it needs to be something that does not take a lot of time as we need the racks done soon.
Thanks

Tanya Tagwerker
store owner - Guelph, Ontario, Canada
2007


Self-Etching Primer


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A. Unfortunately, it's often difficult to get paint to tightly adhere to galvanizing, Tanya. I would try to clean them with TSP [trisodium phosphate [affil. link to info/product on Amazon]] or a strong detergent and a brush, then apply a self-etching primer designed for galvanized metal. While adhesion may not be perfect, it may be fine for your own use in your clothing store.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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