Paleonet: problems with some old thin sections

Tony Wright tony.wright at
Mon Sep 10 07:43:18 GMT 2018

Hi Bruno,

I have had a similar experience with coral thin sections dating back as far as the 1960s. The problem was caused by oxidation of a compound called Permount which was used to attach the coverslips, and this may be the case with your illustrated specimens. With the sections I was using it was possible to flick off the coverslip by carefully using a scalpel (the slip will be loose at the corner or ends) or similar blade and removing the Permount with either more careful scraping and/or cleaning with acetone or Xylol. 

Providing new coverslips should be simple if the original glue was Canada Balsam. In my case it was often Lakeside so great care had to be used to limit the heat otherwise the Lakeside 'boiled', generating disastrous bubbles. This also happened when my technician tried Loctite for coverslippng, and even a few minutes under the UV was a disaster.

Good luck!
Tony Wright

-----Original Message-----
From: Paleonet [ at] On Behalf Of Bruno Granier
Sent: Monday, 10 September 2018 2:00 AM
To: PaleoNet
Cc: PaleoNet
Subject: Paleonet: problems with some old thin sections

Dear Paleoneters,
some time ago, I have inherited a large collection of (petrographic) thin sections, mostly from limestones, prepared to study their microfossil contents.
A significant number displays a centripetal deterioration (see pictures attached). Apparently it affects the glue. May be you have faced a similar problem and I should be very pleased if you could share your "bad" experience:
1) is there a way to revert the process?
2) if not, is there a way to stop it?
"Bien à vous",
Bruno Granier

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