How can I rust or patina metals like brass and steel?

I build reproduction antique furniture and often need to rust hardware components like brass, iron, steel hinges, nails, tacks, etc. Household bleach works fairly well but often takes 2 or 3 days for an appropriate reaction. ...Is there a process that will give me faster and more predictable results? Don Handley 12/06/98

Rather than actually rusting the iron you might consider plating the hardware with a thin layer of copper, which is easily darkened by exposure to sulfides to any desired degree. The copper/sulfide coating will probably rub off easily unless the surface was very clean. You can try protecting the result with laquer.

But I'm a chemist, not a craftsman. I forwarded your question to The Designary, a jeweler who specializes in patinated bronze (among other things). Her response is given below.

There are various recipes for each metal and many ways of oxidizing and prematurely rusting each one. This is an area where a fair amount of reading and experimenting is needed.

You can go the commercial route, which produces some very beautiful effects quickly or you can go the slower, home made route and let the piece age with time. You can also apply a "stopper" which, when reaching the desired color, will stop it at that point.

To go the commercial route, which I have used quite successfully, try www.chemtek.com. There is extensive material on their site, ordering info, on and offline, and an 800 number to call. I have had wonderfully helpful conversations with the owner, who incidentally usually answers the phone pre-working hours.

Another supplier of patinas is Rio Grande, Albuquerque, NM, who I have used for many years. They also have a site, www.riogrande.com, tho specific info regarding rusting and patinas is not available there. You must call them and ask for a catalog. They are a jewelry supply house and do not specialize in patinas, but the material is easily bought there.

Also, try www.artmetal.com. This site is devoted to metal and the trials and tribulations of all artists who are smart enough to know they need a community to share and repair. THey have a great mailing list and all the messages are saved and posted on the site and a search can be done for past articles on "rusting".

The homemade recipes can be obtained in various publications. One that I highly recommend is: Jeweler's Resource, by Bruce Knuth. It is a hard to find publication but can be ordered by calling 509-624-8565. Another book is The Colouring, Bronzing, & Patination of Metals by Richard Hughes and Michael Rowe.

Liver of Sulphur is a compound which you may want to order. One can use it on the various metals. (Liver of sulfur is a colloquial name for potassium sulfide. -Ed.)

Listed below are sample recipes:

To use on Brass or Bronze to obtain an Apple Green color:
6 oz. of cupric chloride
1 oz. ammonium chloride
32 oz. water

Brush on or rinse repeatedly, Rinse in cool water.
To use on Lead to obtain Multiple Colors:
1 oz. ammonium chloride
.5 oz. ammonium molybdate
1 gallon water
Heat solution (140-150°F) dip piece in solution and observe changes. Rinse in cold water when desired effect is reached. Colors appear in this order: golden, green, red, blue,brown and black.

So you see, the patination of metals can be a complex process, but fascinating, nonetheless.

Author: The Designary designary@earthlink.net

General Chemistry Online! How can I rust or patina metals like brass and steel?