Plating fades when the thin gold or silver layer wears away and the brass or copper underneath shows through. It turns black or green when exposed metal, or the plating itself, reacts with sweat, air, perfume or cleaning products.
Some of this is normal wear. A lot of it, especially when it appears within weeks, comes from shortcuts in the workshop.
Causes that start at the workshop
- Plating too thin for the piece, such as a flash coat on a ring.
- Poor cleaning before plating, which leaves oil or oxide under the layer and causes spots and peeling.
- No barrier layer, so copper and zinc from brass slowly migrate into the gold and dull it.
- Porous castings, where tiny holes trap plating chemicals that later seep out and stain.
- Weak or contaminated plating baths, which give uneven colour and thin coverage.
- Missing or patchy lacquer, so edges and recesses are left unprotected.
Causes that start with the wearer
- Sweat, which is salty and slightly acidic, and attacks copper-rich metals.
- Perfume, hairspray and lotions applied while wearing the piece.
- Swimming pools, sea water and hot tubs.
- Storage in damp, open air, especially in humid climates.
- Harsh cleaning, such as toothpaste, abrasive cloths or ultrasonic cleaners.
Green or black marks on skin
Green marks on skin usually come from copper in the base metal reacting with sweat once the plating has worn through. Black marks can come from abrasion of metal particles or from reactions with cosmetics. Neither is usually harmful, but both lead to complaints and returns.
A thicker plating on contact areas, a good barrier layer and a clear top coat reduce the problem considerably.
How to prevent it
- Specify plating thickness, barrier layer and top coat in writing.
- Inspect castings for porosity before they go to plating.
- Ask for an accelerated test, such as salt spray or artificial sweat, on the approved sample and again on a bulk sample.
- Pack in anti-tarnish bags with a desiccant, especially for sea shipments.
- Include care instructions with every piece.
What this means for a buyer
If a supplier's samples darken quickly, the cause is usually in the process, not bad luck. Our workshop audit guide shows what to look for on the plating line.
Creston & Co works for buyers only, for a fixed fee agreed in writing. We check plating lines and finished pieces in Rajkot, arrange tests at NABL-accredited labs and supervise packing. Ask for a free sourcing review.