Kennedy-half error, weird surface sheen. Help!

DieClash

Please help identify this error. There is an unusual sheen on the obverse and revers surface. The shiny area extends out from the center of the devices into the field. It is on both sides of the coin, but is represented better in the oberse image below. Also both devices are distorted in the area of this shiny surface but the edges of the coin outside the sheen and distorted devices seem sharply struck.

I think I may have read a description of this problem in the "Readers Ask" section of CoinWorld a few months ago, but as I recall I don't think the explanation was very explicit.

Does anyone have an opinion on what caused the shiny area and the distorted devices on this coin?

Thanks.

cheezhed

Struck through grease?

fcloud

<< <i>Struck through grease? >>



yup!

DieClash

<< <i>

<< <i>Struck through grease? >>



yup! >>



Thanks for that. So how does the grease make the surface so shiny? I can understand how alot of grease, evidently filling both dies could cause the flat and distored devices upon striking the planchet. But why does it also make the surfaces so shiny?

fcloud

The grease has filled to pours of the die too. Makes it shiny

DieClash

<< <i>The grease has filled to pours of the die too. Makes it shiny >>



Thanks fcloud. I didn't realize the dies were so porous, but that makes sense. It's almost a prooflike surface quality without the mirrored appearance.

FredWeinberg

The dies are not pourous at all.

The "grease" or foreign matter
is coming between the planchet
and the hard dies, at about
45 tons of pressure (could be
diff. now with the newer presses).


It's the "grease" that makes
either the rough surfaces, or the "shiny-er"
surfaces on the struck coin.

It will depend on what foreign material
is on the dies or the planchet.

DieClash

<< <i>The dies are not pourous at all.

The "grease" or foreign matter
is coming between the planchet
and the hard dies, at about
45 tons of pressure (could be
diff. now with the newer presses).


It's the "grease" that makes
either the rough surfaces, or the "shiny-er"
surfaces on the struck coin.

It will depend on what foreign material
is on the dies or the planchet. >>



Thanks Fred!

This is why I post on these boards. The quality and breadth of knowledge contained in the responses is immeasurably valuable.