Remove / Strip Zinc Plating from Steel

A. Kashif: STOP please!

That sounds like a completely ineffective method to strip zinc from steel because the zinc plating is thin, and the steel will remain "wetted" with it; think of hot-dip galvanizing where the zinc sticks to the steel. Plus, the heat is possibly dangerous, environmentally questionable, expensive, and wasteful :-)

Opinion! Rant mode on: Such ideas "for safety" are the harvest of the chemical paranoia that our governments spend so much of your tax money sowing.
Although welders who weld galvanized steel without proper ventilation can inhale clouds of vaporized zinc oxide and get an overdose, resulting in metal fume fever, zinc is not a poison -- it's an essential nutrient. Cold prevention tablets are such zinc salts. Rant mode off.

Zinc is readily and almost instantly stripped in relatively mild acids like inhibited muriatic acid (hydrochloric acid). And other methods like reverse plating are not difficult either if acid immersion is inappropriate for this roll. My question is: who applied the zinc plating? If it was not done in house, then the stripping should probably not be done in house either. Any plating shop capable of zinc plating rolls will be capable of safely stripping the zinc plating. Best of luck!

A. Immersion in a hot caustic solution or room temperature hydrochloric acid will remove the zinc. Your electroplating contractor should be able to do this prior to replating.

A. Dougie is exactly right. When production platers happen to produce a part where the zinc plating is unsatisfactory, they generally don't have to do any specialty stripping at all -- just running the part back through their usual alkaline cleaner and mild acid dip strips the zinc plating.

Luck & Regards,

A. Zinc is quickly stripped in muriatic acid [affil links]. However, this acid is somewhat dangerous for an untrained consumer, the fumes can ruin any metal nearby, and you'll be left with a hazardous waste to deal with. There is also a good chance of hydrogen embrittlement of the bolts. Better would be to find painted or black oxided bolts, and if that isn't possible, to send them to a plating shop for stripping (may cost more than you like). Best of luck.

A. We use HCl to strip zinc from steel. You can use sodium hydroxide too. Why use power when it's unnecessary?

A. Acid stripping is bad news for hard bolts. Hydrogen embrittlement is a very strong possibility. Bake (soon) after strip if you do. Caustic is slower than acid, but it also has a lot smaller risk or attacking the steel. Electrolytic will speed up the operation, but costs more-- a tradeoff.

A. Hi KC. We appended your inquiry to a thread which suggests some other methods, but my question would be why do you need to remove the zinc plating? If the plating is not defective, I think it can be a good base for the e-coating, and will offer sacrificial protection. If you remove the e-coating, you will have to phosphatize the surfaces before e-coating. Good luck.

Regards,

Greetings Mr Ted,
I understand your concern but customer insists on cosmetics. This zinc layer if not removed will form "wavy" surface after E-coat, which is considered as NC regardless how good the adhesion.
Thanks

A. Hi R. Anders. The SDS for Citrustrip mentions only organic chemicals, rather than acid or alkali, so I doubt that it will work. But there's a saying among bridge players that "a peek is worth a hundred finesses" : some things are easy enough to find out that it may not make sense to spend a lot of time in speculation :-)

Regards,

Anything with "Citri" in the name generally contains either citric acid or d-limonene (a.k.a. citrus oil). Citristrip calls itself a paint and varnish remover, which says "solvent" to be, which of the two options would be the d-limonene.

citric acid and citric acid based products aren't that difficult to come by, though, nor is citric the only option for stripping zinc. Any mild acid should work fine, including acetic acid [on eBay or Amazon] (a.k.a. vinegar).