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How to re-finish Galvanized Metal Shelving/Racks for retail use?
Current postings:June 17, 2022
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?
Manager - Hoedspruit - South Africa - Limpopo
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Ed. note: As always, gentle readers, technical replies in public and commercial replies in private please ( huh? why?)
June 18, 2022
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.
Bathgate, Scotland, UK
Closely related Q&A's, oldest first:2007
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.
store owner - Guelph, Ontario, Canada
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, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey