Featured Have you ever wondered what luster looks like?

Discussion in 'US Coins Forum' started by TypeCoin971793, Jan 23, 2019.

  1. TypeCoin971793

    TypeCoin971793 Just a random nobody...

    I recently bought a digital microscope that could magnify objects up to 1600x (maybe not well, but it does work). One of the first things I looked at was a BU Morgan with a light wiping on the obverse.

    This first image was taken at about 800x. You can see the flow lines expanding radially from right to left. You can also see the hairlines going from top left to bottom right. Note how they go over the E; that's how you can tell that they are not die polish.

    Luster1.JPG

    Same magnification, just a different area. The flow lines are a bit clearer.

    Luster2.JPG

    This image was taken at 1600x in the same location as the above image. You can clearly see the ridges that were etched into the die. These ridges reflect the light on one side, which is what causes the cartwheel luster. Also note how the cleaning hairlines disrupt these ridges. That is why an abrasive cleaning will destroy luster.

    Luster3.JPG

    This image was also taken at 1600x, but 180 degrees from the previous image. There was no cleaning on this part of the coin. The ridges are very clear in this image, and you can clearly see how the light is reflected off of only one side.

    Luster4.JPG

    I'm sure all of this is already well-published, but I had fun shooting the images so I thought I'd share. :)
     
    Last edited: Jan 23, 2019
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  3. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes?

    Some of @rmpsrpms super-extremely-enlarged photos show the same thing. This is a really cool effect to see, and your pictures clearly show the flowlines.

    Now, what would be really interesting, is to take a cheap coin (pull a quarter out of a modern roll, or something), photograph the flowlines, and then clean it. Show us exactly how the cleaning would affect these lines.

    Might be cool to compare a few different cleaning methods, while you're at it - how does baking soda vs. wire brush vs. jeweler's rag vs. dip affect the lines?

    I think that first picture, showing the hairlines going up onto the E, is a very valuable teaching tool.
     
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  4. TypeCoin971793

    TypeCoin971793 Just a random nobody...

    I actually thought about doing just that!
     
  5. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes?

    Sounds like a great snowy Saturday project! ;)

    I look forward to seeing your results.
     
  6. GDJMSP

    GDJMSP Numismatist Moderator

    It might be but if it has been I've never seen nor heard of it being published anywhere. But then published to me means in a numismatic article, website, and or book. But it has been discussed on this forum many times and for quite a few years.

    I've talked about how each coin type has its own unique form of luster, and how and why the different forms of luster affect toning for almost as long as I've been on this forum. But in 2006 some of my comments caught the eye of member @USS656 and he decided to take some high mag pics to see for himself. He posted them here -
    https://www.cointalk.com/threads/morgan-toning-vs-peace-toning.12578/

    Over the years several other members have taken the same kinds of pics and discussed the issues. And in each case most folks reading them have learned a good deal. So I would suggest you do your experiments, take high mag pics of different coin types and see the many different forms of luster for yourself. And play around with the wiping, polishing, and different forms of harsh cleaning and then photograph those as well.

    It is by doing things like this that one learns what is really what with coins and how it happens.
     
  7. TypeCoin971793

    TypeCoin971793 Just a random nobody...

    I was calibrating the scope, and the manufacturer blatantly lied about the power. It’s closer to 200x instead of 1600x. 1600x would show bacteria on the surface.
     
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  8. RonSanderson

    RonSanderson Supporter! Supporter

    Mine goes to a point where it is focused, then out of focus as you keep turning, then back into focus when you’re essentially touching the surface. The magnification is much higher. I use that rarely if I want to see doubling on a single letter.

    I don’t want to see bacteria, nope, nope, nope.
     
    I_like_Morgans likes this.
  9. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes?

    Might be cool to compare business strike, proof, and prooflike surfaces under magnification (I honestly would be very interested in that).

    Might be interesting to compare different metals (copper, nickel, silver, gold).

    And, I would be interested to see if there is a different between satiny, creamy, frosty, bold, bright, coarse and other types of luster. There must be some fundamental difference that causes the luster have one appearance or another, and a microscopic view could help illuminate that difference.
     
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  10. desertgem

    desertgem MODERATOR Senior Errer Collecktor Moderator

    The magnification is even more exaggerated I think . I have posted these several times in a group of surface of a morgan compared to a peace @ 100 X ( lab optical microscope) and the morgan @ 400 X . Others are on various threads. It is virtually impossible to get enough light on a non transparent object much closer. The USB mark is usually using the pixel counts. Jim


    .....Morgan 100X........................................................Peace 100X

    comp100.JPG
    .....Morgan 400X
    comp400x-1.JPG
     
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  11. TypeCoin971793

    TypeCoin971793 Just a random nobody...

    I considered doing that, along with toned surfaces. And maybe some AU coins to show what luster breaks look like.

    Interesting. I will look into it. Could you post images of coin with those luster types so I know what you are referring to? I have an idea, but I’d like to be sure.
     
  12. TypeCoin971793

    TypeCoin971793 Just a random nobody...

    I have a line up ready. I’ll take a couple hours this weekend and see what I can do. There is a mix of Proof, Brilliant, satin, subdued, weak, and average luster. There are also coins with crazy die polish and varying degrees of circulation. Should be a fun time. :)

    C3606401-0D15-4BCC-BA37-DB1E4C7024E9.jpeg
     
  13. GDJMSP

    GDJMSP Numismatist Moderator

    When you guys are doing these experiments with high mag pics I think it would be beneficial for those viewing them in posts if you would start off with no or very low mag pics of a given area so folks could see the area of the coin you are talking about. Then gradually zoom in on the same area showing higher and higher mag pics. This would give everyone a relative point of reference so they have a better understanding of how what they normally see looks like at higher magnification.
     
  14. TypeCoin971793

    TypeCoin971793 Just a random nobody...

    I was going to post images of both the whole coin and the magnified coin.
     
  15. GDJMSP

    GDJMSP Numismatist Moderator

    The one doing the experiment, like you, knows what you're looking at because you're the one doing it. And because of that you have an understanding of what it is you're seeing. But those viewing the posts you make lack that understanding because they don't have the comparative reference that you do. So ya have to kind of show them and explain exactly which areas you're magnifying. Only then can they have a better understanding of how the luster they normally see looks when it is highly magnified. That was the reason for my suggestion.

    It's not for me, I know what all the different types of luster on all the different types of coins looks like, it's for everybody else who doesn't. For example, there are still those who think that Proof coins don't even have luster, but of course they do. Proofs have the highest form of luster there is. So experiments and pics like the ones you are taking help folks understand these things, help them learn.
     
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  16. TypeCoin971793

    TypeCoin971793 Just a random nobody...

    The first installment is coins to be circulated coins which have had some luster worn away.

    This coin is a 1914 Barber quarter in VF condition. I believe that the there was some gunk buildup around the devices that preserved the luster as it circulated down to VF condition. This picture clearly shows the presence of luster, and it can be easily seen in hand nder a good light.

    1914 Quarter 7.JPG

    This is a shot in the middle of the field where the lustrous area (right) transitions to the flat area (left). You can see how the luster ridges weaken and then go away altogether.

    1914 Quarter 4.JPG

    This next coin is an AU 1964 half dollar. This coin saw some significant circulation, but here is a section of strong luster in the protected area around the B in LIBERTY.

    1964 Half 1.JPG

    These next three pictures are from the field in front of Kennedy's face. They clearly show the gradual weakening of the luster ridges from being eroded away by circulation. This is why luster weakens with circulation, and then disappears altogether.

    1964 Half 3.JPG 1964 Half 4.JPG

    1964 Half 5.JPG

    The last coin is a 1944 Indian Rupee. This coin would grade a technical AU-58. There is a section of the obverse field in front of George's nose which shows the flattening of the luster due to wear.

    Rupee 5.JPG

    Under higher magnification, we can see how the luster ridges become patchy and plateaued. This would show up as a bald spot in the luster.

    Rupee 4.JPG
     
  17. GDJMSP

    GDJMSP Numismatist Moderator

    And that's the key word - flattening. When a coin experiences wear the metal is not worn away and removed from the coin, the metal is merely smashed down, flattened out. It starts with the luster ridges and it continues on into the advanced stages of wear. And this is confirmed because coins do not lose any weight to speak of until they are worn to the point of being Very Good or Good. Even some AG coins will still be within mint tolerance levels for weight.

    Take this coin for example -

    AGE.jpg AGE rev.jpg


    - even worn to that point it was only 0.003 of a gram less than specified weight. In other words it was still well within mint tolerance level for a brand new coin.

    edit - you can also see that the coin had zero luster left on it.
     
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  18. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes?

    Typecoin, these pictures are fantastic. One request - when you post the closeups, can you also post a regular shot of the whole coin, so people can see what the coin looks like and compare that to the magnified areas.

    I'm really looking forward to seeing more.
     
    TypeCoin971793 likes this.
  19. Insider

    Insider Talent on loan from...

    Terrific post! I'm going to make just two minor changes:


    TypeCoin971793, posted: "I recently bought a digital microscope that could magnify objects up to 1600x (maybe not well, but it does work). One of the first things I looked at was a BU Morgan with a light wiping on the obverse.

    This first image was taken at about 800x. [I don't think this image is magnified anywhere near 600X. I'm not at my scope but I'm going to guess closer to 60X or less.] You can see the flow lines expanding radially from right to left. You can also see the hairlines going from top left to bottom right. Note how they go over the E; that's how you can tell that they are not die polish.

    View attachment 880866

    This image was taken at 1600x in the same location as the above image. You can clearly see the ridges that were etched into the die. These ridges reflect the light on one side, which is what causes the cartwheel luster. Also, note how the cleaning hairlines disrupt these ridges. That is why an abrasive cleaning will destroy luster [Original Mint luster.]

    A cleaned coin has a different quality of luster (THE REFLECTION OF LIGHT FROM A SURFACE) - it is just not Mint luster.
     
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  20. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes?

    TypeCoin971793 likes this.
  21. TypeCoin971793

    TypeCoin971793 Just a random nobody...

    I know. I made the correction in a later comment. I think it is closer to 100x, though I need to calibrate it to determine what it is exactly.

    I agree. I need to be more specific with my terminology.
     
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