Die polish

Discussion in 'Coin Chat' started by GoldCoinLover, Sep 30, 2009.

  1. GoldCoinLover

    GoldCoinLover Senior Member

    Looking at my 1/10 oz fractional buffalo (uncirculated) I ordered from the mint under a 16x loupe, I can't seem to find any die polish. I looked in the recess of the design and through the letters, with no luck. The apperance of the coin has an interesting texture, almost grainy like it was a burnished uncirculated coin.

    How come it is hard to find die polish on it?
     
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  3. bhp3rd

    bhp3rd Die varieties, Gems

    The die had not needed polishing yet?

    The die had not needed polishing yet?
     
  4. GoldCoinLover

    GoldCoinLover Senior Member

    But aren't all dies polished before coins are struck?
     
  5. bhp3rd

    bhp3rd Die varieties, Gems

    Yes but to a mirror finish - die polishing that one can see

    Yes but to a mirror finish - die polishing that one can see or detect is generally only referred to when they remove a die already in service and polish it to extend the life or correct a clash.
    New dies (esp. on this type coin) are poilshed to a point where it's not able to be seen at all - I would not expect to find die polishing marks on your coin under any circumstances except maybe under a microscope.
     
  6. GDJMSP

    GDJMSP Numismatist Moderator

    As I explained before Kevin, what they call die polish lines are not lines caused by polishing the die. The lines are caused by metal flow.

    When die is new, the surface of the field areas are very, very smooth - with no lines visible. But as the die is used the metal of the planchets flows across the surface of that smooth die and gradually wears it away. This creates very fine lines in the surface of the die, but only in the fields areas.

    Now remember, on a die the fields and the protected areas like inside the letters and numbers are the highest points of the die. The areas that stick up the highest. So it is these areas that receive the most metal flow and thus the most lines are worn into those smooth areas by that metal flow.

    Now when those lines reach a certain point that they are considered to be bothersome or ugly, the die is taken out of the press. It is then polished. The purpose of the polishing is to remove the wear lines caused by the metal flow.

    So when someone says that coin has die polish lines - that is not what they should be saying. They aren't die polish lines, those lines are merely the remains of the metal flow lines that were not completely polished out.

    The polishing removes the lines - it does not cause them. And when you can see some still left, it is only because they didn't polish them well enough to completely remove them.
     
  7. 900fine

    900fine doggone it people like me

    This is often true... but has not always been true for all coins.

    In the thread "your old proofs", take a look at two coins I posted - the Pattern 50c 1859 J-242 PR65RB and the 1/2cent 1855 PR62BR.

    Both those coins show very fine parallel lines raised above the fields. Of those two issues, all known coins show those same characteristics; it is clear those lines are a die characteristic. Since "raised on the coin" means incuse on the die, it seems clear those are die polish lines.

    Apparently, 1850s die polishing techniques were nowhere near where they are today. No surprise, really.
     
  8. GoldCoinLover

    GoldCoinLover Senior Member

    Very interesting! I had no idea, I have alot to learn. Thanks all
     
  9. GDJMSP

    GDJMSP Numismatist Moderator

    You also need to remember though that dies used on patterns were not always finished - meaning they were not as well polished as a die for an actual Proof coin would be.

    When talking about regular coins, as opposed to patterns, my previous point stands.
     
  10. The Penny Lady®

    The Penny Lady® Coin Dealer

    These are known as or often called "die flow lines."
     
  11. Leadfoot

    Leadfoot there is no spoon

    Really?

    So the lines on this coin are die wear / metal flow?

    [​IMG]

    (Inside the rays to the left of Lady Liberty)

    And this one:

    [​IMG]

    (To the right of Liberty's bust)

    I couldn't disagree more.... Those are die polish caused by die lapping, not die flow/wear.
     
  12. Leadfoot

    Leadfoot there is no spoon

    IMO, there are die polish lines and there are die flow lines. They are quite different but similar looking phenomenon.

    Die flow lines extend radially on the coin -- they are caused by die wear.

    Die polish tends are most often in a roughly vertical or horizontal direction but can be in any direction and sometimes even in a number of directions -- they are caused by manipulation/polishing of the die during preparation and/or lapping.

    Die polish is much more common on older coins. I'm not sure what they changed, I suspect two things are at play: 1) they just used to use dies much longer in the old days and therefore were more likely to polish/lap them to increase their life, and 2) modern polishing techniques don't leave polish lines like the old technique.

    Respectfully...Mike
     
  13. GoldCoinLover

    GoldCoinLover Senior Member

    Ok, so looking at my PCGS (former ANACs slab) AU58 $5 1908 indian head under a 16x loupe, I immediately go to the neck area. I don't see toolmarks, but what appears to be a dozen or so horizontal, fine lines. Barely visible. Is this die flow lines or die polish?

    Confusing...
     
  14. Leadfoot

    Leadfoot there is no spoon

    I'm sorry, I don't know the series well enough to even guess. If it were a large cent, it would be another story...but with incuse gold my head starts to spin.

    Do you have a high-resolution photo of the feature?
     
  15. GoldCoinLover

    GoldCoinLover Senior Member

    I have 2 photo's I took when I had my Digital Blue Microscope up and running, I have to set it up on another computer, don't have the space to do it in this house. Here are 2 photo's I took, although they aren't in the same area of the coin. I'm sure the coin is genuine, I just want to know what I'm seeing.

    [​IMG]
    [​IMG]
     
  16. GDJMSP

    GDJMSP Numismatist Moderator

    There are exceptions to every rule Mike.
     
  17. Leadfoot

    Leadfoot there is no spoon

    GCL, That looks like die flow in the pics. However, I would check with a specialist in the series to be sure.
     
  18. Conder101

    Conder101 Numismatist

    In Kevins pictures the top one does show a polish lines (and a few flowlines), the bottom one shows mainly flowlines but there is one polish line just a little above the center of the picture.
     
  19. GoldCoinLover

    GoldCoinLover Senior Member

    I noticed that too. So, in short, what I've made from my observations. Die polish lines go through the field and ON the devices, where flow lines are only in the recessed areas and do not go on the devices? Is this correct?
     
  20. GDJMSP

    GDJMSP Numismatist Moderator

    No. You do not find polish lines on the devices. But you can find flow lines on the devices.

    Basically you can find flow lines anyplace on the coin. But they will most commonly be found in the fields.

    Polish lines typically are only found in the fields and protected areas. There is of course an exception - the 3 legged Buffs would be one. But that happens when a particular device area happens to be pretty close to the surface of the die - almost at the same level as the fields in other words.

    Then, if a die is polished down enough so that highest points of the die reach that level that the device is on - then that device can show polish lines as well, or even be polished away like with the 3 leggers.
     
  21. GoldCoinLover

    GoldCoinLover Senior Member

    Err, I think I was confused. I think I know why now In the coin in question, the design is 'incuse', and it looks to have die polish on the 'raised' part of the coin (the devices), but since the design is incuse, these are actually the fields! (lowest part of the coin)

    The fields of the coin are the highest point here. I think this is right?
     
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