[Nhcoll-l] crack formation in glass stoppered jars on display

[Ian Hart]

We have had tadpoles (mounted on glass slides) on display in old
ground-glass stoppered jars containing 10% formalin since September 2014.
In the last 6 months (of 2016) two of these jars have developed
(apparently) spontaneous cracks in the neck of the jar. Nothing could have
struck the jars from without.

Has anyone experienced cracks like this? If so, were you able to find out
what caused them?

We want to put the specimens back on display, but would like to rule out
the display environment as a contributing factor to the cracking problem.
The jars are on display in an illuminated cabinet. We do not have case
temperature data for the time that the cracks occurred, but we have
subsequently recorded a maximum daily temperature fluctuation in the case
of 4.25 deg F (from 70.803 deg F to 75.075 deg F)

I would gratefully appreciate any relevant information you have to share on
this subject.

---
Ian Hart

Preparator
Exhibit Studio
California Academy of Sciences
55Music Concourse Drive
Golden Gate Park
San Francisco CA 94118
(415) 379-5879
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