Best way to remove hot dip galvanized coating?

[jzhaan55]

I have a bolt that is HDG and I would like to remove the zinc layer to look at the cracking under the microscope. What is the easiest way to remove this coating without damaging the base metal?

 

[Compositepro]

Hydrochloric acid. It does not have to be concentrated. Vinegar and salt will also work. Use detergent and water to remove any oils first.

 

[swall]

And rinse with water after the acid stops working, which you can tell when it stops bubbling/foaming.