Removing Zinc From Galvanized Metal

Iron and steel are often protected against rust by giving it a coating of zinc metal, a process called "galvanizing".

Unfortunately, welding galvanized metal produces vapors that are bad to breath. I don't know if there are any long-term effects, but in the short term, the welder who breathes the smoke of welding galvanized material may suffer from "metal fume fever".

The symptoms begin about 4 hours after exposure. The symptoms include fever, chills, thirst, headache and nausea. Recovery occurs within 48 hours.

In addition to "don't breathe the smoke", one can prevent this problem by removing the zinc from the metal near where the welding is to take place.

This page discusses how one might do that.

Dissolve It With Acid

Notes:

Hydrochloric acid is nasty stuff. Do it outdoors. Wear gloves. Dispose of used acid properly.

Our acid was pretty strong; we diluted it. Add the acid to water, not water to acid.

Mix the acid and use it in a glass container.

We had this corroded old bottle of 31% hydrochloric acid.

We diluted it 50/50 with water.

Here is a bundle of several pieces of galvanized steel conduit, after sitting in the acid for a few minutes.

Here is the result - nice and clean.

When done, wash the metal very thoroughly with a lot of clean water.

Removing Zinc From Galvanized Metal

Dissolve It With Acid

Grind It Off