Rusting nails quickly

I am making some shelves for my home. They contain some nails to hang things from. I want to rust the nails so they will look old. How do you suggest I rust the nails as quickly as possible?

First of two simultaneous responses --

If you want the nails to look really old, find a hardware store that sells square cut nails. They have a black finish and are closer to old nails than any new round ones. The larger ones are still sold as concrete nails.

Second of two simultaneous responses -- 2004

You can use 15 grams iron chloride/1 lit water solution! Diluted hydrochloric acid also must work. Only for grease free objects! Use rubber gloves ⇦ on eBay or Amazon [affil link] and goggles ⇦ on eBay or Amazon [affil link] !

You can rust the nail by getting a glass bowl put a paper towel into quarters and wet it until its completely wet then put the nails in and put salt in it (1tsp)first you have to sand the nails. After that fill the bowl in with vinegar ⇦in bulk on eBay or Amazon [affil link] until all the nail are covered up wrap the bowl with paper real tight and see what happens then. After a few days (3 or 4)and they are rusted.