What exactly ARE hairlines?

I'm going through the PCGS grading standards and comparing their photograde pics to various slabs and raw coins, and I'm definitely getting better. But I don't understand hairlines - what are they? How are they produced? Are they just discolorations? Or tiny cracks in the planchet?

 

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http://www.ngccoin.com/news/viewarticle.aspx?NewsletterNewsArticleID=511

 

Hairlines are basically tiny , usually shallow, incluse scratches on the surface of the coin from handling or small amount of circulation. Die polishing lines are similar in low magnification appearance, but they are raised and from abrading/polishing the die , thus they are not wear or damage.

 

Ok, so the standards say that at MS63, you can have a moderate number of hairlines, but the photograde pic of an MS63 Kennedy is covered with them. Or is this considered moderate? Or would these lines turn out to be die polishing marks under magnification?

 

The coin you have in the image is smothered in die polish.

 

Like Tom said, that's die polish lines on the Kennedy, not hairlines (damage). Sometimes it can be hard to distinguish the two from pics, but in that case it's pretty obvious. Notice how the lines are in the fields but don't run across the devices; that's because on the die the devices are the most recessed regions, so they're almost never susceptible to polish lines.

This Morgan is a good example of extreme polish lines (see the reverse): http://www.ebay.com/itm/1881-S-Morg...63?pt=Coins_US_Individual&hash=item19d5e23e93

 

As an extension to what raider34 has stated, hairlines will often travel unbroken from the field and then over top of the raised devices and back down to the field again. It is quite unusual for die polish lines to do this.

 

Thank you, gentlemen.

 

Please let me complicate matters a tiny bit.:devil: Sometimes, proof coinage will show strong die polish on the devices and this can be with or without die polish in the fields, too. Below is a 1953 proof Franklin half with strong die polish on the portrait that is mostly horizontal within the hair (bald head) portion as well as on the clothes, but is primarily vertical on the face. There is also a little bit of die polish in the field near the date. The reverse shows die polish on the Liberty bell and this is most easily visible near the bottom of the bell on the viewer's left side. Images are embedded, but I have included links for larger images, too. The coin is in an old fatty NGC holder as PF67 and has a CAC sticker, too, so you can be fairly confident that I am not making up the die polish statement.



http://wsm.ezsitedesigner.com/share/scrapbook/23/239107/TBI1953N67W.jpg

http://wsm.ezsitedesigner.com/share/scrapbook/23/239107/TBI1953N67WR.jpg

 

Thanks for the oversize images Tom - that makes the die polish abundantly clear. Why does a die need to be polished? Is it something that's done before planchets are struck, or does it correct some sort of problem in the middle of a run?

 

Get a proof coin. Take an eraser, like the one on the end of any pencil. Rub said eraser across the fields of said proof coin. Viola, you have hairlines.

Also, said simply, hairlines are dug into the surface of a coin (i.e. incuse), and die polish are above the surface of the coin (i.e. in relief). Another way to think about it is die polish are lines on the die and hairlines are lines that were not on the die. Yet another way to think about it is the coin left the mint with die polish, but someone or something had to make the hairlines on the coin after it left the mint.

While not always easy to tell in a photograph, they are easy to distinguish in-hand with good lighting, a good loupe, and a bit of experience.

 

Here is an 1880 Proof 64 Morgan. If you look particularly at the obverse, you can see thin, delicate scratch like lines in the fields to the left and right of Liberty. Those are hairlines.

 

Yes, I can see those clearly. Would that have happened by the coin getting tossed around in a bag?

 

In the case of proof coins the dies would be polished before any coins were struck, but after a given number of strikes the die begins to wear and starts to develop the microscopic flow lines that cause cartwheel luster and not the mirror smooth fields of a proof. Back in the 50's and 60's they would repolish the dies to remove the flowlines and restore the mirrors (Today they just retire the dies). Normally the polishing would not get down into the devices but with the big open areas like bust of Franklin or the Liberty bell it was a possibility.

 

In the case of proof coins the dies would be polished before any coins were struck, but after a given number of strikes the die begins to wear and starts to develop the microscopic flow lines that cause cartwheel luster and not the mirror smooth fields of a proof. Back in the 50's and 60's they would repolish the dies to remove the flowlines and restore the mirrors (Today they just retire the dies). Normally the polishing would not get down into the devices but with the big open areas like bust of Franklin or the Liberty bell it was a possibility.

Sometimes just wiping a coin with a cloth can cause hairlines. The reason for this is dust. Believe it or not a modest portion of household dust is made up of silicon dioxide or silica crystals, otherwise known as quartz or sand. It has a hardness of about 7 which is greater than most metals. o if your cloth has dust on it it is like dragging a piece of extremely fine sandpaper across the coin with the silica crystals leaving very fine scratches behind them.

 

An even easier way to get used to die polish marks is to take early memorial reverse dated (BU) lincoln cents -- the 60's were notorious for having tons (and heavy) die polish marks. For the year 1960 you're almost guarenteed to see them on every coin.

Check out http://coppercoins.com/diesearch.php and type in 1960, denver mintmark, mintmark variety and you'll get a bunch of high-resolution, close up pictures of die polish lines.

While most coins do not exhibit such strong polish lines as lincoln cents, they still may exist as thin and light ones.

 

I came across this thread looking for some information about this.
This is why....

 

Proof Franklin half dollars from 1953 are very commonly found with severe die polish. Below is one that I own in an old fattie NGC PF67 holder with a CAC sticker. The obverse die polish matches that found on Franklin's cheek for your coin. Mine also has die polish on the coat, which I would expect yours to have, too, as well as die polish on the Liberty bell.

 

Nice Tom. Your post about this coin is where google pointed me. Thanks for the info.