Patinas for Your Jewelry

May 27, 2010 § 3 Comments

Thank you Shaiha, for your question. You got me thinking, and reaching for other resources.  (http://shaihasramblings.blogspot.com) . Shaiha asked about a patina for brass. There are a lot of ways to color metals, depending on what color you are looking for. Many of the chemicals are hazardous; in fact, most are required to be shipped ground. I do mention a less toxic means of adding a patina to bronze. There is also a website listed that has a few handfuls of recipes for patinas, and a great book that’s on my wish list.

Patina. A patina is oxidation, a chemical change that occurs when metals come into contact with oxygen. Oxidation often happens naturally, and in those cases we aren’t often glad to see it. Oxidation can also be used as a decorative element in art and jewelry.

There are three forms of oxidation: hot, cold, buried. I have seen just hot and cold listed, with ‘buried’ listed under cold applications.

Cold patinas include patinas resulting from burial of the object, cold chemical patinas, and patinas created with fumes. These don’t need heat to produce change, but heat will destroy them.

example: for a vivid teal green:

  • Vinegar
  • Ammonia or uric acid (if desired)
  • sawdust, cat litter (used cat litter is  better)
  • Moisten sawdust or litter with vinegar (well moistened). Add ammonia or uric acid if you wish. Put the mixture in a bag with the bronze piece. Check on the piece after several days. The teal green happens with just vinegar. Bluer colors emerge if you add the ammonia.

The above method is one of the least toxic. It takes the longest, and you have very little control over the process.

Other cold processes, which happen at approximately room temperature, include gun blueing and liver of sulphur. These processes do happen more quickly if the piece you are oxidizing is hot. The chemicals involved are either stronger or more concentrated, to be able to work without heat.

Hot oxidation isn’t always considered a chemical reaction. Heat means the oxidation happens more quickly. It also means that heat is likely to darken it. The amount of heat, the chemicals involved, and method of application all affect how the oxidation appears. These involve the least time, are the most controlled, and don’t require quite as strong or harsh chemicals. That said, you need to know that if you are using heat, it is that much more dangerous.

Once the piece reaches the desired color, the oxidation needs to be protected. If not protected with some sort of coating, the piece may continue to discolor, or it may be easily removed. There are a number of things you can use as coatings, including renaissance wax.

There are great books on the subject. Here is one to look into:

The Coloring, Bronzing and Patination of Metals, by Richard Hughes, Michael Rowe

An interesting site and a variety of recipes that I haven’t checked out. Feel free to check it out.

http://www.sciencecompany.com/patinas/patinaformulas.htm#index

Kim

kim@of-the-earth.org

**Standard disclaimer: I don’t recommend using any chemicals without proper training, equipment and experience. Any and all of these examples should be done with proper equipment, including (as examples) a fan hood that is directly above your work; a mask (respirator version); whatever else your instructors, lab assistants, etc. recommend.

Advertisements

§ 3 Responses to Patinas for Your Jewelry

  • Hilde says:

    Thank you very much for this interesting post! I’m curious, what do you mean “heat will destroy it” when you mention the cold patina? Does that mean if I leave it out in the hot sun like behind a window it will loose the effect of the cold patina and the patina will disappear? Does the brass get its original color back then?

    • Hey Wezz! Good to see you! And a great question.

      Mentioning patinas…the head required to ‘destroy’ it is usually warmer than the sun. An example:
      I used liver of sulfur (cold patina) room temperature to patinate my friend’s tortoise ring. I cleaned it up, patinated, then put it in an ultrasonic for a short time. The ultrasonic was a little too warm, and when I pulled it out, most of the patina was gone. I then repeated the process with liver of sulfur, and cleaned it up with a toothbrush wet with cleaner from the ultrasonic. Without the heat, the patina stayed put.

  • Shaiha says:

    Thank you so much for answering my question! I have always loved that teal green but didn’t want to wait forever for it to occur.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s

What’s this?

You are currently reading Patinas for Your Jewelry at Off the Bench.

meta

%d bloggers like this: