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

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.

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 [on eBay or Amazon] , get it down to nice clean steel and clear coat it.

Luck & Regards,

Hello Ted,

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

I will finish the shelf today.

All the best ,

David

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 [on eBay or 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.