Plating

By Anna on May 19, 2007 at 2:10 pm

Plating:

We first considered plating so that we could use
vintage, non-precious metal for some elements of our
first collection. We could enhance the elements by
plating them in precious metals, but still use a great
deal less gold. But plating is a dirty process… Is
it better to use that much less virgin material when
we are incorporating a process that involves caustic
chemicals?

In electroplating an electric current is passed through a solution that contains dissolved metal ions and the metal object that will be plated. The metal object serves as the cathode in an electrochemical cell, attracting ions from the solution. Generally, metal objects are dipped into a series of baths that contain various reagents to achieve the desired surface characteristics. A plating sequence usually involves several steps of cleaning, rinsing, stripping, and plating. In electroless and immersion plating the process is similar, but the metal coating is deposited onto an object using a chemical, rather than an electrical, reaction (EPA 1995).

The most harmful by-products of plating are sludge and wastewater containing the chemicals used to ‘clean’ the metal to be plated. The aqueous solution used for plating baths becomes waste water containing cyanide and metal wastes. Fortunately, working with valuable materials encourages precious metal platers to recapture any metal that might escape.

As jewelers trying to learn the source the metal we use, we run into a familiar problem in plating. Companies do not to trace each source of metal. It all goes into a big batch
together. Again, the vast majority of precious metal
is recycled because it is far too valuable to waste.
The larger plating companies we spoke with told us
that about 90% of all gold on the market is recycled.
But again, they don’t track the source of the metal
they use, they buy it from chemical companies like Technic or Advance Chemical who buy it from …who knows.
Small-scale platers have an easier time handling their
waste water. They may have permits like a small
science lab, and pay for their municipality to handle
the water treatment for them.

In our research of plating companies, we talked to a
lot of environmental organizations to get a clearer
picture of precious metals plating and it’s negative
environmental impact. Compared to other types of plating, precious metals plating gets a pretty good rep with the waste
prevention agencies, largely because they keep close
tabs on such valuable materials.

No one we spoke with had any recommendations of plating companies with a better than average track record.
NEWMOA (NorthEast Waste Management Officials Association, www.newmoa.org) was the most helpful. They suggested the
following questions to ask a plating company:
-Has the company implemented any pollution prevention steps?
-Is the company doing anything to learn about pollution prevention steps they might take (e.g. an environmental audit)?
-Can the company cut back on water use?
-Does the company employ counter-current rinsing (this is a technique that requires less water)?
-Has the company explored any alternatives to chlorinated solvent cleaning?

Other Plating Resources on the internet:
– The EPA enforcement tracking site, where you can find the enforcement history of a company & check if they have ever been non-compliant or penalized.
www.epa-echo.gov

– The Pollution Prevention Resource Exchange has a Metal Finishing Topic Hub with lots of information, and a reference section with over 100 articles on metal finishing.
http://www.p2rx.org

– The National Metal Finishing Resource Center is a national compliance assistance center partly funded by EPA to help metal finishers improve their compliance with environmental regulations.
http://www.nmfrc.org/

Comments (1)

  1. Wow. Great info about the NMFRC. I really need to be more aware of my environmental processes. Thanks, rust-belt!

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