Zinc Plating an old auto radio case

[engineerscott]

I'm wanting to restore an old car radio from the mid 1960s (to go into the mid '60s car I am restoring). The outside case appears to be made from 3 or 4 pieces of stamped and folded "galvanized" mild sheet steel (16 gauge maybe). The exterior has some surface rust where the zinc coating has broken down and the steel beneath has begun to oxidize (i.e. rust). The rust isn't too severe, mainly just surface rust - no pitting. Even though this part of the radio isn't normally visible I'd like to restore it to like new condition. I don't know for sure if the zinc coating is hot dipped galvanized or electroplate but I'm leaning pretty heavily towards it being electroplated.

Seems like I need to remove the rust and whatever is left of the original zinc coating to get back to bare steel and then prep the steel and plate using one of Caswell's zinc plating kits. What I'm asking from you guys is advice as to what is the best way to remove the existing zinc and rust. I'm thinking a solution of hydrochloric acid will probably remove the zinc. Will it do so without overly attacking the mild steel underneath? I'm thinking it might even remove the rust, but if not I think I can take care of that with simple sanding.

Has anyone had any experience doing anything like this? If so any advice you can give me would be appreciated.

Thanks,

Scott

[eprigge]

Re: Zinc Plating an old auto radio case

Hydrochloric acid will remove the zinc rapidly as you probably already know. It will also remove the rust pretty quickly, maybe 5-10 minutes for a 1/3 solution (1/3 concentrated acid). You want to make sure the surfaces are clean/degreased before dipping in the acid to make sure it acts uniformly. Exposed iron will slowly dissolve in the acid so you don't want to leave it in too much longer than necessary. The de-rusted bits won't look shiny, they will be a matte gray but are clean of rust and will take plating fine.