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Zinc-Lye Cleaning Method for Rusty Iron Artifacts

The Zinc-Lye Cleaning Method for Rusty Iron

If you are not comfortable working with caustic chemicals do not try this at home. When using this method for cleaning rusty iron artifacts always use metal containers. The dry residue from the process can cause plastic to combust. And remember a byproduct of the chemical reaction is free Hydrogen, "Remember the Hindenburg". Use of this method outside is best.

Use a good set of lab quality rubber gloves, goggles for eye protection, and I keep a bottle of a base (vinegar) handy to neutralize any Sodium Hydroxide that may make skin contact.

Normally you will want Sodium Hydroxide in the “Technical Beads” form as it will be less expensive. Some chemical companies do not sell small quantities. Here is a link to a site that presently has their “food grade” Sodium Hydroxide cheaper than their “technical beads”:

Essential Depot – Sodium Hydroxide

This recipe can be scaled for larger containers. In one (1) gallon hot water stir in slowly three (3) cups of powdered Sodium Hydroxide (NaOH), also known as lye and caustic soda. DO NOT just dump the Sodium Hydroxide into the water or you will get a very violent splash back.

Next stir in one-half to one cup of powdered Zinc. In the past powdered Zinc was available from paint companies that used it in primer paints. When the powdered Zinc is well suspended in the solution, lower the rusty artifact to be cleaned into the solution. If the solution is working properly you will get a fairly enthusiastic boiling action. If the artifact does not have good metal under the rust, you will be left with nothing.

I usually check in 4 to 6 hours to see how it is going. I will remove the artifact and brush it with a steel brush. If it needs more cleaning, stir the solution to get the Zinc suspended again and place the item back in the solution. Then check as needed.

After you get the item down to bare iron you can keep repeating the process and you will get a chemical Zinc galvanizing on the item that will keep it from rusting.

Properly dispose of all solution and residue.

Here is a Civil War Artillery Projectile, a Selma Bolt, that was found by my father and cleaned using this method back in the late 1970’s. As you can see it has still not rusted.


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