Coloring sterling silver or other metals

A. 1. I'm not personally familiar with electrophoretic coatings on silver, but they work fine on steel, zinc, copper and brass... and no alarm bells are going off about silver being special. Good luck.

Regards,

A. 2. Different thicknesses of oxide layer on steels (even low grade stainless steels) give different colours. Experiment with heating samples to red heat for different times and then quenching in water. You'll be pleasantly surprised. IMPORTANT: For consistency, ensure that the parts are consistently polished. Let me know how it goes.

A. Hi Julie. I think you might make faster progress if you explain what you are trying to accomplish, or what properties you are trying to impart to the surface. A problem with your inquiry is that "anodizing" doesn't mean much in this context -- it merely means making the part anodic in a processing bath.

While anodizing of aluminum can add a super abrasion resistant hardcoat to the surface with a honeycomb topography that can be reliably dyed, and while anodizing of titanium may imply adding a transparent and very thin layer of titanium oxide to impart diffraction colors ... what does anodizing of sterling and gold even mean to you other than merely exposing it to an anodic current? I am not saying that you cannot 'anodize' silver & gold in some way or other for some purpose or other ... I am saying please don't confuse it with anodizing of aluminum or titanium. You cannot anodize & dye silver and gold as if it was aluminum. Thanks.

Regards,

Q. Dear Mr. Mooney,
Thank you for helping me redefine what I am trying to accomplish. It has helped me in getting better answers from local shops.

I am looking for a process to make sterling silver and gold a different color while maintaining the metal's sheen and feel. Some people have suggested powder coating in candy colors to achieve the bright hues I am looking for, but I am not sure it would retain the metal "feel" to the items since it creates a coat over the metal. I have also looked into a process similar to powder coating, but works partly like plating, named Kliar and it is made by Legor Industries. The reviews I have heard so far is that this coating is not durable.

I am looking to make rings in bright hues, so the process selected has to withstand daily wear.

Anodizing was considered, since many of the colors I am looking for are available. The pieces would therefore be anodized so they may be dyed, rather than enhance any mechanical properties of the metal. I was told that since silver and gold are both inert metals, small part of aluminum would have to be included in the piece so the anodizing and dying work.

From experience, because the item will be worn, would you recommend anodizing as a durable finish once it is dyed and sealed? If this process is not the best, would you have other suggestions besides powder coating?

Thank you in advance for sharing your experience and knowledge with us!

A. Hi Julie. I'm not personally aware of any useful process for anodizing gold or silver. The anodize-plus-dye process in question applies only to aluminum and actually only to quite pure aluminum.

The Kliar process is a brand name for cathodic electrodeposition (also called e-coating, electropainting, electrophoretic lacquering). This process is similar to electroplating except that it deposits organic coatings (paints) rather than metal ones. The coatings are much thinner than powder coating, about 2 to 4 ten-thousandths of an inch thick. It is possible to do a subsequent UV-cured hard clear coat on top of the colored cathodic electrodeposition coating for additional durability if you wish.

My own opinion as an occasional wearer and buyer of rings, not a designer, is that designers need to recognize that rings get exceptional wear, and no thin coating can possibly last on the exposed metal. Surely the trick must be to design with painted groves and recesses, rather than painted prominences. Good luck.

Regards,

A. Hi Rick. Rings are very high wear items and any coating on them will wear through rather quickly. Hard coatings applied by PVD will last longer but I don't know if that info can help you because you haven't introduced your situation yet (it might help if you are a manufacturer of tens of thousands, but not if you are a home-based supplier with a handful of commissions).

(To show dark relieved areas)
Courtesy: Balfour.com

If you are designing and casting the rings, you may take advantage of the knowledge that the blackening will wear off of the high spots but not the relieved spots. You'll never see a high school ring where the coloration is the opposite of this .
with the high spots black and the relieved areas shiny :-)

Regards,

A. Hi Timothy. I'm at a disadvantage here because I've never seen or heard of this coloration process for silver that you and others keep alluding to. But I would suggest making such a rose out of titanium rather than silver because it is fairly easily anodized in rainbow colors (although you naturally should acquire some experience anodizing scraps before trying it on your prized rose).

Regards,