Coin Preservation Handbook by Charles Frank
fiddler
Posts: 27
I saw some posts about this book on the forum recently so on a whim I checked out Amazon.com and sure enough there was a used copy for sale. It arrived today.
It had a lot of interesting information for me, but I have very little experience with this stuff anyway. It's 40 years old so a lot of the information is dated. Much of it is geared towards providing advice to companies that manufacture coin holders, such as flips with PVC and other items which now are known to be destructive. I guess when it was written much of this wasn't known.
There is a lot of specific information on differnt techniques and solutions but I've read refined techniques posted here by forum members that cover it pretty well, and in a practical way.
I found the discussion of galvanic and electrolitic corrosion particularly interesting. He lists metals in order of galvanic response and how one metal can draw the corrosion from another. I have not read any specifics on the "aluminum foil and baking soda" technique that's been mentioned here but according to his chart aluminum would act as an anode and draw the oxidation from silver, which would act as a cathode. I don't think baking soda is correct, though, since I didn't see that as an electrolytic agent in the book.
Anyway, it was pretty interesting to me so thought I'd share. Now if I could only find a crucible furnace I could set up in my kitchen...
It had a lot of interesting information for me, but I have very little experience with this stuff anyway. It's 40 years old so a lot of the information is dated. Much of it is geared towards providing advice to companies that manufacture coin holders, such as flips with PVC and other items which now are known to be destructive. I guess when it was written much of this wasn't known.
There is a lot of specific information on differnt techniques and solutions but I've read refined techniques posted here by forum members that cover it pretty well, and in a practical way.
I found the discussion of galvanic and electrolitic corrosion particularly interesting. He lists metals in order of galvanic response and how one metal can draw the corrosion from another. I have not read any specifics on the "aluminum foil and baking soda" technique that's been mentioned here but according to his chart aluminum would act as an anode and draw the oxidation from silver, which would act as a cathode. I don't think baking soda is correct, though, since I didn't see that as an electrolytic agent in the book.
Anyway, it was pretty interesting to me so thought I'd share. Now if I could only find a crucible furnace I could set up in my kitchen...
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<< <i>Now if I could only find a crucible furnace I could set up in my kitchen... >>
Nice info.
Perhaps the price is just too steep.
Is your conscience at rest if once put to the test?
You awake with a start to just the beating of your heart.
Just one man beneath the sky,
Just two ears, just two eyes.
In reference to corrosion. Cathodic protection of metals is used in all sorts of industrial situations like underground tanks, ships, etc... On ships, I believe they have a huge block of zinc cabled to the hull. The zinc corrodes first and leaves the hull intact. When it's "used" they just put in a new block. I'm not sure how that could be used for coins since they would have to contact the metal. I suppose Intercept shield does something similar by surrounding the coins with metals that corrode easier than coins do.
What I've just written comes from past conversations with my father, who is a PhD Metallurgist. I may not have all my facts correct so if anybody please correct me if I'm missing or misstating something. I'll try to talk to him this weekend to make sure I was correct.
collections: Maryland related coins & exonumia, 7070 Type set, and Video Arcade Tokens.
The Low Budget Y2K Registry Set
6,593,007
and here is an excerpt from the patent which shows what it is all made of
"In the preferred embodiment of the invention, the reactive polymers are those available from Engineered Materials, Inc. of Buffalo Grove, Ill. under the trade names Static Intercept.RTM. and Corrosion Intercept.TM.. The corrosion reactive polymers are manufactured by catalyzing copper material into polymer chains to form a homogeneous polymeric/metallic structure of low-density polyethylene (LDPE). The static version uses the structure of the corrosion polymer plus an additional catalysis of C12 into the poly-metallic structure to form a copper/metal/oxide semi-conductive media, which utilize the `Bucky Ball` phenomena to provide paths for electron flow within the structure. The LDPE structures are formed into standard pellets and processed into various final structures, the most common of which is blown film to manufacture bags. Once incorporated with reactive polymer, the surfaces of the packaging preferably have a chemically neutral pH (preferably in the approximate range of 7.0 to 7.5). Packages are designed so that, when closed, they have RP on the majority of the inside surfaces. In the preferred embodiment of the invention, the treated surfaces of the packaging have greater than two square centimeters of RP surface per square centimeter of surface of the product to be protected therein. Further preferably, the permeability of any package cross sectional structure is approximately or less than 0.015 g/M.sup.2 Moisture Vapor Transmission Rate. Also in accordance with the invention, the paper based packaging materials are comprised of cellulose-based packaging materials, which are of high alpha-cellulose content and are negative to lignin side chains. When packed with the material to be protected, the unfilled interior volume of the package is preferably less than 25% of the total interior volume of the enclosure. In addition, adhesives are avoided in the packaging (and/or in the product), or adhesives are used having chemicals that do not contribute to the corrosion or other degradation of the material to be protected."
And here is a link to Intercepts earlier simpler patent for a copper impregnated bag
4,944,916
and here is an excerpt from the earlier patent
"Corrosion of metals such as silver and copper by sulfur and chlorine containing entities are substantially prevented by surrounding these materials with a suitable polymeric structure. The structure should be a polymer containing a material such as copper or aluminum that reacts readily with corrosive gases. In one advantageous embodiment a polymer bag containing approximately 35 weight percent of dispersed, powdered copper is employed to enclose a metal containing structure such as a printed circuit board. Use of this expedient substantially reduces corrosion of the printed circuit board."
www.backyardmetalcasting.com
The book was describing the metals in electrical contact with each other, such as in salt water. which he says applies to moisture in the air if you live near the ocean. I got the impression that they did not necessarily have to be in physical contact if they were in the same enviroment and that environment had electrical properties, like moist salt air. So a penny would protect a box of siver coins if it was tossed in by actually drawing the oxides to it.
Thanks for the metalcasting link. The flower pot crucible looks functional and an attractive addition to the garden as well!
I've done some model ship building and have been amazed at the tools available to modeling. There are a lot of tabletop manufacturing tools available for hobbists, including metalcasting. I was thinking about looking through some of them but haven't done it yet. Don't know if I'm really ready to try and set up a coin conservation lab here. But the book gives it high marks!
Accordint to the patent on Intercept, it works by impregnating copper particles into absorbant polymer.
I wonder if the shield itself will haze or darken over time as the copper oxidizes. The coin will stay the same but you might not be able to see it!