Die polish lines vs cleaning?

[CSdot]

How do you tell the difference between die polish and cleaning on a coin? Can you trust that a coin with lines like that slabbed by NGC would be displaying die polish and not cleaning lines?

 

Thanks.

[BillJones]

Die polish lines are raised above the surface of the coin because they are "into" the surface of the die. Cleaning lines are into the surface of the coin because the abrasives that were used on the coin scratched the surface.

 

It often takes a strong glass (10X) to detect this, which is why purchasing a high qualty close-up lens is a very good investment.

[dimefreak]

I think die polish lines are much easier to see than a cleaned coin. The hairlines from cleaning are wispy and the best way to distinguish without a strong glass is if the wispy lines are on the devices. Rarely do the polish lines disturb the devices.

[Kurtdog]

Can you trust that a coin with lines like that slabbed by NGC would be displaying die polish and not cleaning lines?

Yeah, I think so, sure.

[Dcoin]

Die polish lines are raised above the surface of the coin because they are "into" the surface of the die. Cleaning lines are into the surface of the coin because the abrasives that were used on the coin scratched the surface.

 

It often takes a strong glass (10X) to detect this, which is why purchasing a high qualty close-up lens is a very good investment.

 

Bill your wonderful early gold piece (the exact year escapes me) is a great example of how die polish lines can be mistaken for cleaning. Not to put you on the spot but do you have an old pic?

[halfpint]

 

...die polish lines are raised on the coin, hairlines are incuse on the coin. die

 

polish lines do not criss cross each other, hairlines often do criss cross

 

each other.

 

 

[coinman_23885]

Die polish lines are raised above the surface of the coin because they are "into" the surface of the die. Cleaning lines are into the surface of the coin because the abrasives that were used on the coin scratched the surface.

 

It often takes a strong glass (10X) to detect this, which is why purchasing a high qualty close-up lens is a very good investment.

 

+1

 

With regards to the second question, I think NGC is reliable in differentiating between the two. In the event that any error is made, you are aware that you can enforce their guarantee, right?

[No+4Me]

Die polish lines do not show up on the devices, since they are recessed into the die. They also tend to be short, in groups, and very straight. I don't think the graders would mistake them for anything else. Here is a dime with some polish lines in the fields

 

[Mozin]

Here is a good example of die polish lines. Notice that the raised areas show no lines.

 

 

[lehigh96]

Although rare, I have seen die polish lines on the devices of the coin. This photo of a Jefferson Nickel should be a teaching tool for die polish lines.

 

 

Notice the die polish lines on Jefferson's coat collar.

[dimefreak]

Lehigh- You are right thats why I used the word rarely.

 

As for die polish lines not criss crossing.... I think they do and most the time cleaned coins will have hairlines going in the same direction

[brg5658]

Here an example I have of die polish lines:

 

[RWB]

The assorted raised lines and squiggles on coins result from maintenance and repair of dies - not from "polishing." They can be parallel or not, depending on how the maintenance was done and what was necessary to correct the die surface. These also occur within the raised portions of the design but are much more difficult to identify.

[physics-fan3.14]

The assorted raised lines and squiggles on coins result from maintenance and repair of dies - not from "polishing." They can be parallel or not, depending on how the maintenance was done and what was necessary to correct the die surface. These also occur within the raised portions of the design but are much more difficult to identify.

 

What kind of maintenance and repair are you talking about? Such as after a clash? I've definitely seen later date coins, with evidence of clashing, that exhibit heavy die polish - to the extent that they are now prooflike. I'm guessing they would take the wire brush and remove the clash, and then polish it with a finer medium.

[RWB]

Clashing, spalling, minor surface cracking, damage…. The die steel had to be softened, the defect removed and then hardened and tempered. Emery wheels could be used on hard dies and those produced the largely parallel lines as shown on the dimes and nickel. Lines on the Pilgrim half were probably done with an emery stick by a very inexperienced die maintenance person.

 

"Polishing" brings a surface to a greater level of smoothness up to the point of a mirror surface, and is usually intentional. (PL dollars and mirrored areas on Peace dollars indicated that this was sometimes inadvertent.)

 

[VDBCoins]

Although rare, I have seen die polish lines on the devices of the coin. This photo of a Jefferson Nickel should be a teaching tool for die polish lines.

 

 

Notice the die polish lines on Jefferson's coat collar.

 

I have also seen die polish lines on at least one of the 1964 SMS Jefferson nickels, all over Monticello.