Expert: Thomas - 11/8/2004

Question
I purchased an old brass mirror at a thrift shop over the weekend and was hoping to create a tarnished blue/green patina.  Do you know of any products that would help speed up the oxidation process?

any help is appreciated!
Thank you,

Adam Loucks

Answer
Hello Adam,

Thanks for the question.   I will give a website showing some of the available patination chemicals available.  You might check other sites with a search for similar products. Often, these are listed under “oxidizers” and “patina” at various jewelry suppliers' sites.
You might also find some of the chemicals at a good hobby shop, possibly dealing with model trains, dioramas and other things in which a hobbyist might want to create a realistic coloration in metals.  Unfortunately, some products are simply paint like materials and do not produce a real patination.  Fortunately, some of the paint like items might be just what you want to try if the chemicals do not suit you.

Once in a while if lucky, you can find similar chemicals at a gun dealers though generally limited to “blue” for steel.

Here is one jewelry tools and supplies dealer:  www.contenti.com   This is a well established business which has been around many years.  Here is the direct link to the patina chemicals:

http://www.contenti.com/products/plating/520-805.html

Another possible site to try is www.alpha-supply.com, a good company with an indexed catalog on the net.  RioGrande at www.riogrande.com has the chemicals but do not have an on-line catalog.  Local crafts stores often order from RioGrande and may let you see a catalog and order the chemicals for you.

SPECIAL CONSIDERATION WHEN METAL IS TO BE CHEMICALLY COLORED
First, realize that the chemicals used to color brass and other metals are generally poisonous and some are acid based.  Care must be exercised in using the chemicals and good ventilation is recommended to avoid fumes.

Cleanliness of the metal is the beginning of a good job of coloring brass or other metal with a nice, aged looking patina.  Perfectly clean metal is the true KEY to obtaining a good patina coloring.  If the chemical process starts with metal the least bit dirty, the job will simply not do.    The metal should be totally free of dirt, oils and in most cases free of previous coloration from weathering.   Clean metal is needed for the chemicals to reach in and do the job.  After all, the idea is to duplicate that which would take nature exposure extended time to create, haphazardly depending on the environment and you want the look to be very pleasing and natural looking to the eye.

Cleaning may be done on a small scale with a repeated scrubbing with good dish detergent.  Sometimes, a scratch brush is used (depending on the look you want) or a paste of pumice and water.  Regardless, the item must be free of lacquers, oils and anything else.  Rinse well and do the coloring at that time to prevent natural discoloration layers on the metal from interfering with the job you want to do.

A shiny surface on the metal will generally result in a shiny patina.  A brushed or more satin surface will generally result in a satin backed patina.  Keep this in mind!  If you shine the surface or brush it, do the work immediately to allow a uniform coloration.

I put a greenish patina on an engraved brass plate for a largemouth bass I caught. I allowed the chemicals to work and rinsed, applied again and again.  I was able to develop a “raised” sort of color, almost encrusted on the edges of the engraved plate. This is delicate and handling would mess up the raised effect.  Since the fish is up on the wall, handling of the plate is not a problem.  With a brass frame you might consider a light coat of wax over the patina for protection and do not try for a raised look…just go for the intriguing antique color.

Keep in mind that some of the chemicals are considered hazardous for shipping and shipping cost truly escalate when the hazardous charge is added on.  Check this before ordering.  Hopefully, you can find the stuff locally in containers small enough for the job and not much leftover.   These chemical mixes are not outrageous in price but are not cheap.

APPLICATION.  
The chemicals come with instructions and often the disclaimer: “for professional use only”.    Some work better when heated or when the brass is warmed before chemical application.  Warming the metal with a hair dryer will do, getting it warm but not hot. Hot metal causes too quick a chemical reaction and results in a much less permanent or uniform coloring.

Small areas may be applied with the chemicals using cotton swabs and similar items.  (Do keep the chemicals off the hands and skin and away from kids and pets!)


Well, Adam, that is the answer.  I do hope the info helps.  Please let me know if you need more information or if any part of this one is not clear to you.  Wishing you the best in the project.

God Bless and Peace to All.            Thomas.                   11/9/2004 9:24 PM