Intercept Shield - Or Just A Sacrificial Copper Bar?

I started thinking about Intercept Shield based on the comment that the Coin Chemistry book is just an advert for their products. So I started to wonder what the technology really is.

Searching for Intercept Shield led me to a NJ court case for breach of contract (http://docs.justia.com/cases/federa...328/20/0.pdf) which indicated the Intercept Shield technology was invented by John Franey in 1993 and 1995 and assigned to Lucent. Well, Lucent didn't exist back then, but a bit of patent search led me
to US Patent 4,944,916 - https://www.google.com/patents/US4944916.

The most important part of any pattent is the claims - this is what is protected. The rest is just explainations around the claims such as why this is new and novel and thus patentable. Most of the verbage is bogus (I know, you should read my patents some day...).

For the '916 patent the claims are:




(This is referenced by the second patent - 5,154,886 - https://www.google.com/patents/US5154886,
but there's nothing much new there)

So back to '916 and it indicates that the protection against corrosion (tarnish) is that there is raw copper metal to absorb the Hydrogen Sulfide in the atmosphere: "As discussed, the corrosion of metals such as silver or copper by sulfur or chlorine containing entities is avoided for substantial periods of time by surrounding the object containing these metals with a specific enclosing structure. In particular, a polymer material forming the structure should contain a substantial surface area of either copper or aluminum." The metal is in the '916 patent example in the form of "7 μm diameter copper powder".

So I started to wonder. This sounds no different than the sacrificial anode used in boats and home water heaters: something that corrodes easily to protect the things you don't want to corrode.

The patent describes using flakes not power, "The greater the surface area of the protecting metal, e.g., the aluminum or copper, the more efficient the corrosion protection. Generally, particulates of the protecting metal are dispersed in the polymer. Metal flakes (as opposed to metal spheres), interdispersed in the polymer produce greater surface area per unit weight and thus more efficiently protect from corrosion. However, particle geometries such as spherical geometry do provide protection and are not precluded."

You can easily buy copper powder - 44 microns not the 7 in the patent example - on ebay for about $25/pound. You can buy copper bars for maybe $10 per pound (spot today is around 3.44).

So really, what is different from a plastic bag with copper flakes embedded in it, or a coin album with copper flakes incorporated into the pages - or a copper bar.

Nothing.

At the elemental level, the only difference between a flake, a powder and a solid is surface area. You get a lot more surface area from a flake or power for the weight. But so what if you had to rub the copper bar with a piece of 000 steel wool every couple months to expose more bright copper? It would certainly work. The '916 patent talks about using the color change of the bag (i.e. as the copper tarnishes) as an indication when the protection is no longer provided.

A little rough on the copper bar, but sacrifices sometimes have to be made for the greater good.

So here is what I'm thinking:

Buy a plastic tub - something inert (not PVC - recycling labels will help here) - and a couple copper bars. Store my coins - in their flips, slabs, raw, whatever - in the tub. Each time I look at my collection, add to it or deaccession something: check the bar and shine it up if it's tarnished. Boom. Poor-man's Intercept Shield. $10. And I'm not infringing on the patent because I'm using solid copper not particles.

Anybody want to tell me I'm crazy?



PS: the patent has actually expired, since it was filed on/before June 8, 1995 it was valid for whichever is the greatest of a term of 17 years from the date the application was granted (Jul 31, 1990) or 20 years from the date the application was filed (Aug 23, 1989). So after August 22, 2009 anyone can make polymer bags with copper or aluminum flakes or powder embedded in them.

As always, I Am Not A Lawyer (As this is a family-friendly environment I'll skip the usual acronym) and free advise is worth what you paid for it, not one cent more.

-----Burton