very good info. on flips
littlejohn
Posts: 702
Important Notice To The Numismatic Community From PCGS
- September 2, 2004
OVERVIEW
For a number of years, the Professional Coin Grading Service has observed an unusual and distinctive mark on a few coins it has examined. The mark is in the form of a light scratch that runs vertically down the center of the obverse of the coin, usually from the eye, down the center of the cheek, ending in the area of the lower jaw or chin. While this scratch has been seen on a handful of coin types, the overwhelming majority have appeared on only three issues: Morgan dollars, Peace dollars and $20 Liberties.
The uncanny similarity of the damage led us to believe that a single factor was the culprit. After over a decade of study, we have finally determined what we believe to be the cause.
THE CAUSE
PCGS is of the opinion that the cause of the light vertical scratch occasionally seen running down the obverse of large, heavy coins is due to sliding the coin over the surface of a flip containing poly-vinyl chloride, also commonly known as PVC. Coins are often slid over a flip's surface in the process of inserting it or removing it from the flip.
The direct cause of the damage is the presence of small particulate matter imbedded in the surfaces of the flip. These particles were confirmed through the services of Berkeley Engineering and Research, Inc., who subjected both the coins and flips to examination with a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS). These particles ranged in size from approximately 5 to 15 microns. EDS spectra representative of approximately 50% of the particles analyzed showed peaks of silicon (Si), sulfur (S), chlorine (Cl), potassium (K), calcium (Ca), iron (Fe) and zinc (Zn).
High power magnification indicated that what appeared visually to be a single scratch, was actually a series of fine, parallel scratches, consistent with what might be made by an irregular, rocklike particle. PCGS believes that the weight of a large coin (such as a double eagle or silver dollar) sliding over a "dirty" surface of a PVC flip, can, on rare occasions, produce the scratches that have been observed. Particles large enough to produce a visual scratch are infrequently seen, but particles in crystalline form are certainly hard enough to be capable of scratching silver or gold.
THE SOLUTION
Clearly, the use of PVC flips entails not only a long term risk of surface contamination, but also a short term handling risk. Great care must be taken to "cup" the flip, and drop the coin in, taking special precautions not to slide the coin over the surface of the flip. Even given this degree of care, PCGS does not recommend the continued use of these flips, and will no longer take responsibility for scratch damage to coins submitted in PVC flips.
Mylar® flips have been analyzed, and while they are not completely free of particulate matter (which may come from the atmosphere) the laboratory observed much fewer particles on the inner surface of the Mylar flips than the PVC flips.
The best solution at this point, is to use Mylar flips, and ensure that the coins are "dropped" into the flip rather than slid over the surface. Again, at greatest risk are the large heavy coins such as Morgan and Peace dollars and $20 gold pieces. Franklin and Barber halves would carry a smaller risk. Small coins (quarter size and under) carry virtually no risk whatsoever.
you can see the pic. here.-
http://www.pcgs.com/articles/article_view.chtml?artid=4243&universeid=313
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this is real good info.i hope someone look at it .this time around.
littlejohn
Stuart
Collect 18th & 19th Century US Type Coins, Silver Dollars, $20 Gold Double Eagles and World Crowns & Talers with High Eye Appeal
"Luck is what happens when Preparation meets Opportunity"
Jerry