How to Oxidize Galvanized Metal

Galvanized metal has a protective layer designed to prevent rust, but wearing off that layer helps oxidize the metal beneath it. If left outdoors, it takes quite a long time to wear off that layer of zinc or galvanization from the metal, but with a little sanding and vinegar, it's easy to oxidize the metal within a day.

Galvanized metal buckets, watering cans, and tubs are all perfect candidates for oxidization. No matter the actual galvanized metal item, the process for oxidizing is similar. In some cases, you might want to oxidize the outside of the item and leave the inside as is since the inner area is less visible anyway. Leaving the protective zinc layer on the inside of the item is also a good idea if you plan to put liquid in the item at all, such as using a tub as an ice bucket or as the container for a small water garden or fountain.

Set the galvanized metal item on some scrap paper or a tarp, ideally outside. While wearing rubber gloves, scuff up all the areas you wish to oxidize using medium-grit sandpaper, steel wool, or a sanding sponge. Keep sanding until the metal feels rougher than it did before. Afterward, wipe down the metal object with a damp paper towel to remove any fine particles.

Vinegar is the secret sauce that oxidizes the metal by creating a chemical reaction with it, much the way the elements oxidize metal left outdoors for months or years on end. Depending on the size of the item, the process involves dipping it into a shallow pan filled with vinegar or applying paper towels soaked in vinegar atop the metal object. Work outside or in a well-ventilated area if the smell of vinegar bothers you.

If you're using the tub-soak method, find a plastic tub large enough to set or lay the metal object inside it. Fill the tub with an inch or two of vinegar depending on the size of the metal object. Set the item on its side in the vinegar for about 30 minutes and then flip it over to treat the other side. Repeat as needed to treat all the areas you're oxidizing. Lift the item out of the vinegar. Rinse it off if you're happy with the level of oxidization or let it air-dry as is, which may oxidize it just a little more.

For a larger item or if you don't want to waste a lot of vinegar, set the object on a plastic tarp or within a plastic tub. Soak paper towels in vinegar and then set them sopping wet on the areas you wish to oxidize. As the paper towels dry out, pour more vinegar on them. Oxidation is obvious within about 30 minutes. If desired, enhance the oxidization effect afterward by spraying the metal with salty water and then letting it air-dry outside.