Noddy78 said:
That's brilliant! Thanks mate, I've been clear-coating the rusty bits I've done, but obviously that kills the feel. Are you saying boiling a rusty piece of metal in tea will halt the oxidization and make the rust a permanent non-corrosive finish? I always wondered how they did that. Will definitely look into this more...
There is a bit more to it than that, but yeah. The traditions and methods involved span over a thousand years, so there are many methods. Most involve inducing rust in a controlled manner, followed by halting and stabilizing the rust, and there is usually a top coating for extra measure. Most commonly that is a wax of some kind.
For your purposes either start with natural rust or induce the rust with hydrochloric acid, boil in tea. I would still clear coat just to be thorough. Just clearing rust won't create a maintainable patina. The oxidization is still happening under the clear. It will eventually slough off. The tea halts that reaction with the tannins. Modern rust converters are mostly industrial grade tannic acid.
There are more complex ways to get different colors. If you feel a little braver and want a nice chocolate brown the favored method at followingtheironbrush.org is as follows.
Vinegar 250 ml
Water 125 ml
Salt 5 grams
Copper Sulfate 1.5 grams
and 5 grams of liver of sulfur. ( Potassium polysulfide )
Clean the steel with a bit of alcohol (medical not consumable
) and dry. The oil on your hands can affect the evenness of the rust, so glove up. Brush on the recipe above, and hang the part in a open air environment (outside cause liver sulfur smells like rotting eggs). Allow to hang 24 hrs, an brush on a second coat and give it another 24 hrs. Repeat until you're happy with the color. Each day you can maintain the evenness of the rust by LIGHTLY brushing with a toothbrush if desired. When you have what you want boil the piece in a neutralizing bath (baking soda and h20) for several minutes. You can also add a tea boil prior to the soda bath to alter the color further.
Different steels will react differently, so experiment a bit. This would be marginally ineffective on chrome I would think. There are countless methods out there as well so look around a bit. Have fun, and play safe.
-Daniel