Message:

<p>[QUOTE=&quot;physics-fan3.14, post: 918623, member: 19165&quot;]What You Need to Know About Contact Marks</p><p>By Jason Poe</p><p><br /></p><p>The third in an ongoing series of articles about the basics of grading, this article will hopefully be interesting and help you understand one of the key aspects of grading uncirculated coins. Contact marks cover a wide area of dings, scrapes, marks, and ticks that will reduce the grade of a coin. Bagmarks are a specific kind of contact mark caused when coins impact each other, often leaving reeding marks on the face of a coin. The term “bagmarks” is often applied to the wider meaning of marks in general. Contact marks are incredibly important on uncirculated coins, but lose importance for circulated coins, where wear becomes more important. However, even on a lower grade circulated coin, a smooth unmarked surface is considerably more attractive than a heavily marked coin – and commands an understandable premium. </p><p><br /></p><p><img src="http://i277.photobucket.com/albums/kk68/physicsfan/various/contact%20marks/1832.jpg" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /></p><p>(A 1832 Bust Half Dollar displaying incredibly smooth surfaces). </p><p><br /></p><p>Several criteria are used to judge the impact of a mark on the grade of a coin. The size and depth of the mark, especially with relation to the size of the coin, are important. A mark which appears very severe on a dime may go nearly unnoticed on a large silver dollar. For example, assume a mark is 1 millimeter long. On a dime (roughly 18 mm diameter) that is 5.5% of the coin’s width. On a silver dollar (roughly 38 mm wide) that same 1 mm mark is only 2.6% of the coin’s width – a significant relative difference. </p><p><br /></p><p>Even more important is the location of the mark. Most coins are divided into about three different levels of importance: primary focal areas generally include large open fields, the cheek, the eagle’s breast, and any areas of a coin where your eye is naturally first drawn. Secondary focal areas are less important – areas such as complicated designs like hair details, wreaths, or less important areas. The tertiary areas are those around the edges, and areas similarly outside the main focus of the coin. Any divisions beyond 3 levels add unnecessary complexity. </p><p><br /></p><p>To illustrate this point, let’s look at a couple of coins. The 1962 Franklin below is accurately graded at 64, due to the large mark on Franklin’s temple (well within a primary focal area). The rest of the coin is very nice, but the mark occurs in a prime area – so it is downgraded a point. The 1934D Walker reverse, on the right, however, is graded 65 because the mark occurs in a secondary area – despite it being of similar severity as the mark on the Franklin. The remainder of the coin is technically superb, but the one (somewhat severe) mark brings it down a grade. The number and severity of the marks which are required to bring a coin down a grade are subject to opinion. I could show you dozens of coins with similar marks, but which received different grades. This is due to variations in the other factors we have discussed (and which we will continue to discuss) – primarily luster, strike, and eye appeal. </p><p><br /></p><p><img src="http://i277.photobucket.com/albums/kk68/physicsfan/various/contact%20marks/marklocation.jpg" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /></p><p>(Contact marks on a 1962 Franklin and 1934D Walker) </p><p><br /></p><p>So how are these dreaded bagmarks formed? Well, the obvious answer is when the coins are in bags. The more complicated answer is any time between striking and delivery of the coin to the collector. After striking, a coin is ejected into a large bin with hundreds or thousands of other coins, each falling and jostling on top of each other. The coins are sent through machines which weigh and sort them, further jostling. They are put into bags, rolled, dropped, heaved, shipped, transported, jostled, and subjected to all sorts of treatment we numismatists would find deplorable. But to the mint, they are just a product. Their mission is to get as many coins to as many people to facilitate commerce, while looking reasonably decent. They really don’t care about preserving the ultimate perfect coin in MS-70. For this reason, bagmarks are the norm. Different mints and different eras tended to produce coins of differing quality. Knowing the series you collect will help you evaluate the marks on your coin. For example, for the Franklin, S mint coins were generally very well treated and display few bagmarks; D mint coins were generally badly mistreated and show tremendous amounts of bagmarks. </p><p><br /></p><p>The other important factor affecting bagmarks are the material properties of the metal with which the coins are made. Coins are generally made of four metals. Ranked in order from hardest to softest, they are: nickel, copper, silver and gold. What this means is that it is much easier to produce a severe mark on a gold coin than a nickel one. The same force applied to each coin will tend to produce a much larger mark on a gold coin, because it is softer (the metal is easier to move). </p><p><br /></p><p>So, after thinking about bagmarks for a bit, my curiosity was piqued. Exactly how much does it take for a coin to show a bagmark? What sort of mistreatment will produce the marks and scrapes that I see on all my coins? A little research was in order. I took a few bright and shiny Lincoln cents (low value coins, perfect for experiments), and did everything I could to beat them up. I performed a series of semi-unscientific tests to show exactly what sort of damage will occur to your coins with mistreatment. </p><p><br /></p><p>I took a couple of pennies in rather good shape (I would grade most of them MS-65 before my abuse), and subjected them to tests. In the first image below, you see the original cent. The first test I performed was using my brother’s ammunition press, to which he has attached a torque wrench. (He reloads his own ammo, for an interesting diversion, read his website here: <a href="http://www.rifles-shooting-reloading.com" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://www.rifles-shooting-reloading.com" rel="nofollow">www.rifles-shooting-reloading.com</a>) We put a penny in the press, and attached a pin to the shaft to make small circular depressions. After four such tests, we produced the depressions as shown below. The torques used were 10, 30, 45, and 60 inch-pounds of torque (the smallest being the lowest depression, closest to the date). It is quite reasonable to say that the first mark is similar in severity to many marks we see on coins. Using several conversions to put it in terms a scientist can understand, this is a little over 1 Newton of force. For reference, gravity acts with a force of roughly 9.8 Newtons.&nbsp; </p><p><br /></p><p><img src="http://i277.photobucket.com/albums/kk68/physicsfan/various/contact%20marks/IMG_7272.jpg" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /></p><p>(The un-marred cent)</p><p><br /></p><p><img src="http://i277.photobucket.com/albums/kk68/physicsfan/various/contact%20marks/IMG_7273.jpg" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /></p><p>(The ammunition press used for testing)</p><p><br /></p><p><img src="http://i277.photobucket.com/albums/kk68/physicsfan/various/contact%20marks/IMG_7277.jpg" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /></p><p><img src="http://i277.photobucket.com/albums/kk68/physicsfan/various/contact%20marks/IMG_7280.jpg" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /></p><p>(The gauge-meter, reading 30 inch-pounds)</p><p><br /></p><p><img src="http://i277.photobucket.com/albums/kk68/physicsfan/various/contact%20marks/IMG_7284.jpg" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /></p><p>(The results – the lowest depression is 10 inch-pounds, increasing to 30, 45, and 60 inch-pounds)</p><p><br /></p><p>Next, I performed a drop test. I dropped a penny from a height of approximately a foot onto another penny on my desk. After several tries, I finally hit the target, and produced the mark you see in the obverse field below. During the minting process, it is entirely reasonable to believe that the coins are subjected to drops of a foot or more traveling from the striking chamber to the bin, or into a bag, or any number of other places. While the severity of the mark will depend on the weigh, size, angle, and hardness of the coins, I’m sure this mark is a representative example. For reference, these solid copper pennies (dated 1961D) each weigh 3.11 grams. </p><p><br /></p><p><img src="http://i277.photobucket.com/albums/kk68/physicsfan/various/contact%20marks/IMG_7286.jpg" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /></p><p>(The mark produced by dropping a penny from a height of one foot onto another penny is clear)</p><p><br /></p><p>There has been a recent discussion about contact marks, with some wild claims being made about marks. Let’s examine the mark I just created on this coin and see if we can’t dispel some of these arguments. First – notice the mark on the coin is straight. Yes, the curved edge of a coin can create a straight mark for the simple reason that it is curved if you look at it from the obverse, but completely straight if you look at it from the edge. There is more than one perspective for everything. Notice next how the mark appears tapered. The tapering is due to the curvature of the coin. If the impacting coin had hit the target coin at a different angle, the tapering would of course be different. Further evidence that a round coin can indeed make a straight mark is provided by the Franklin below. Notice the series of reed marks across the top of the bell on this 1961D Franklin – which are perfectly straight. Again, the angle of impact plays an important role in the shape, severity, and appearance of the marks. I hope we can all agree that these marks are caused by the impact of one coin on another (as has been generally accepted by numismatists). </p><p><br /></p><p><img src="http://i277.photobucket.com/albums/kk68/physicsfan/various/contact%20marks/reedmarks.jpg" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /></p><p>(Reed marks on the reverse of a 1961D Franklin.)</p><p><br /></p><p>Still not content with my trials, I took the penny you see at left, with relatively clear surfaces, and placed it in a bag with 4 other pennies. When a mint bag is filled, there are $50 worth of pennies – or 5000 pennies. The weight of these coins is tremendous, and will severely affect the pennies below them. However, I don’t have a mint bag or 5k pennies to test, so this will have to do. I simulated the rough treatment a mint bag of pennies will receive by vigorously shaking the pennies in my Ziploc bag for approximately a minute. In a mint bag, there is far less room for the coins to travel as the bags are densely packed, but the vibrations last much longer, are often more severe, and have a lot more weight to damage coins. After one minute of shaking, the cent came out well marked, as shown below right. This is very similar to the appearance of many coins fresh from the mint. Again, this test is highly un-scientific, but it will give you an idea of what sort of mistreatment is required to produce the bagmarks we see on coins. The corollary, of course, is that you will come to highly appreciate MS-65+ coins for the scarce gems they are. </p><p><br /></p><p><img src="http://i277.photobucket.com/albums/kk68/physicsfan/various/contact%20marks/bagmarks.jpg" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /></p><p><img src="http://i277.photobucket.com/albums/kk68/physicsfan/various/contact%20marks/IMG_7294.jpg" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /></p><p>&nbsp;(A relatively mark-free coin, left, goes into a bag, right, and comes out well-marked, below)</p><p><br /></p><p>The final experiment I wanted to try was another drop test. You always hear horror stories about rim bruises due to dropping coins on concrete or tile, so I wanted to see just how bad it could be. I took the penny you see at left, with a relatively unmarked edge, and dropped it from a height of about 5 feet onto my concrete patio. As you can see, the edge is considerably marred. </p><p><br /></p><p><img src="http://i277.photobucket.com/albums/kk68/physicsfan/various/contact%20marks/edgebumps.jpg" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /></p><p>(An unmarred penny at left, dropped 5 feet onto concrete, shown right). </p><p><br /></p><p>There are numerous variables associated with each of these tests, and they are by no means conclusive as to predicting the size and shape of marks. However, it should be perfectly clear that a small coin, dropped from a relatively short height, can indeed produce significant contact marks. The size and weight of the coin, composition of the target coin, angle of incidence, and a host of other factors will of course change the size and shape of the marks – but they can and do happen. </p><p><br /></p><p>Learning to evaluate the marks you see on a coin will help you determine the grade of that coin. Although marks are the easiest factor of grading to see and identify, the severity of these marks are often subject to opinion. A mark that downgrades a coin to 64 in the eyes of one numismatist may be acceptable on a coin graded 65 to another collector. Also remember that marks are not the only criteria for grading a coin – strike, luster, and eye appeal also play important roles. </p><p><br /></p><p>I hope this engenders some interesting discussion, </p><p><br /></p><p>Jason Poe[/QUOTE]</p><p><br /></p>

Your name or email address:

Do you already have an account?

• No, create an account now.
• Yes, my password is:
• Forgot your password?

Stay logged in