Have you ever noticed an ugly round spot on the inside of a vintage glass ornament? And wondered what caused it?
It is caused by a flaking away of the interior coating of the ornament. The cause is moisture from the air condensing onto the inner surface and then evaporating away, taking some of the inner coating with it.
So why would this happen in only spots and not the entire inner surface?
When the ornament is stored, the moisture will condense at the bottom most point of the ornament. This causes that spot to flake and the surrounding surface to flake less.
How can this be prevented?
Store glass ornaments in climate controlled conditions where the temperature does not vary widely. Then evaporation and condensation aren’t likely to take place. Some collectors advise to store ornaments with the top down so that moisture will collect there and not on the inner surface. However, this should not be necessary if the ornament is stored in climate controlled locations.
Can this be repaired?
Unfortunately, the answer is “no”. Recoating the inner surface is usually not an option since the formulas used for the inner coating vary and it is difficult to tell what the original formula might have been.
Is there ever a situation where this sort of damage is desirable?
Opinions vary on this. But many people love the satiny glow caused by even flaking of the entire inner surface. They call it patination and think of it as a lovely indication of age.