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COIN CLUB
"Air bubble" in coin
A. Bubbles in a coating applied over a casting are caused by trapped porosity.
Heat causes air or moisture trapped in porous pockets in the substrate to rupture
through the coating as the air escapes.
Bubbles in coating over a steel part also are most likely caused by trapped air or moisture.
1998 decimal penny with several "air bubbles" in the metal.
Obv. Below H of ELIZABETH and below the 2nd "I" of II. Also between 19.98 of date.
Listed as OP 1998 C - AU90. A couple of tiny ex-carbon spots on cheek and on bubble
2008 decimal penny with a couple of "air bubbles" in the metal.
Obv. Above and between the A B of ELIZABETH and larger bubble above and between B E of
ELIZABETH. Listed as OP 2008 D (2nd issue 'Shield' type reverse) - AU95.
2010 decimal penny with a couple of "air bubbles" in the metal.
Obv. Above and between the I Z of ELIZABETH.
Listed as OP 2010 C - AU95.