Improper storage and sudden change in climate exhibited this with many series through the years; most recent being the CHC and Crocks material.. Proof being; the oldest-of-the-old dating back to early SBM and Vichy, where examples in their original state of preservation exist.

10,000 (in sacks) of some oval 500f SBM found in New York State 24-years ago were completely brittle when found, while examples of that same series that have been in collections since 20-years prior are as new as can be.