QuestionHi Thomas! I read your answer to Kelly about how to remove oxidation from her silver ring. You did an excellent job on that! My question is the opposite of Kelly's. I would like to know what chemicals I need to procure to be able to dip a piece of silver chain, etc so that it will become coated w/black oxidation. I work in a lab so I have access to some simple chemicals. Thank you for taking the time to help me with this.
AnswerCheryl, the basic and most common chemical for creating a dark patina on silver alloys is Liver of Sulfur, also called potash of sulfur. As available in small broken chunks of a solid, the material is certainly not a pure refined chemical compound.
To use the chemical, take a small pea or slightly larger piece and put into a Pyrex or other heat handling glass dish with enough hot water to cover it and the item to be colored. Temperature increases the reaction of sulfur with the silver to produce a yellow to gray to black patina. Light oxidation colors such as golden yellow are not durable. The liquid resulting from dissolving a small amount of the solid in hot water may be painted on the silver with a swab of some sort or the item may be immersed. Oxidation may be removed from highlight areas with mild abrasive polishing. There are some health concerns but I see those as minimal. You may want to look up a materials handling sheet and see for yourself.
Description from a jewelry website:
Liver of sulphur is Potassium pentasulphide, which is mainly
K2S5, but there are small amounts of other potassium sulphides with
it. Hence the name, 'potassium polysulphide'
Keep in mind, the item to be given patina should be clean and free of oils, etc. Soldered areas will not take the color as uniformly as sterling without solder on the surface. Silver with a tarnish preventative plate such as rhodium will not take the patina. The surface needs to be silver, sterling or another alloy of silver. The oxidation mimics the natural patina of silver brought on basically by sulfur related compounds in the environment, however in a fraction of the time required for natural patina to form.
Using liver of sulfur will provide the closest to natural oxidation. Other chemicals are on the market to patinate silver but the color is not so hardy or is simply not the same as natural patina.
Cheryl, once the item appears to have the darkness you want, rinse and dry. You may buff for highlights or leave as is. There you go! All in all the process is quite simple and much is a try it and see how it goes sort of action. You need a solution with some brownish yellow color from the dissolved chunk of chemical but how concentrated is not defined in a meaningful way. Simply dissolve the chemical in a dish of hot water (less than a simmer) so you have a yellowish brown liquid and go for the patina! Check the item as time passes since all depends on time, concentration and heat.
Best wishes. Get back with a follow-up if needed. God Bless and Peace. Thomas.
BTW, check out sellers such as www.contenti.com and other "jeweler supply" websites for the stuff if there is nothing suitable closer to you.
