[Nhcoll-l] Bakelite

[Dirk Neumann]

just to add to Paul's comment:

same applies to (kautex) wide neck plastic bottles: 
https://urldefense.proofpoint.com/v2/url?u=http-3A__www.fisher.co.uk_1_1_210583-2Dcontainer-2Dsquare-2Dwide-2Dneck-2Dpvc-2Dcrystal-2Dclear-2Dseries-2D200ml.html&d=AwID-g&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=Ji7L_taUrYr4MdLeLHIKOBUXcCuEEEbc8h8h51zTu4M&s=kj75ONINNLrSb5tqzNNuX14dEkM7R-kghMI-mSZdcjg&e= 

These containers are used in some herpetology collections, but over time 
the plastic gets brittle and cracks, same applies to the lids. Both, 
Bakelite and phenolic resins are phenol formaldehyde resins and share 
the same CAS-number. The problem is the exposure to formaldehyde gas in 
the long run (any residual formalin trapped inside the specimen 
container, e.g. tiny amounts dissolving from specimens) which changes 
the (chemical) structure of the plastic.

Dirk


Am 01.11.2015 um 18:47 schrieb Callomon,Paul:
> Following Dirk's comments on Bakelite: a distinction should be drawn 
> between Bakelite and phenolic resin. The former uses wood dust as a 
> filler, and is not stable under mechanical stress (such as in a screw 
> top) for long periods. Phenolic, however, seems (from our sampling of 
> 50-year-old-plus bottles) to be very stable, showing no micro-cracking 
> or other stress symptoms. However, as Dirk points out, neither 
> material should be exposed to Formalin vapor or submerged in 
> preservative. If (as was previously done in our collection) submerged 
> internal vials are capped with phenolic lids, the latter will stain 
> the alcohol even if Formalin was never present.
>
> *Paul Callomon*
> /Collection Manager, Malacology, Invertebrate Paleontology and General 
> Invertebrates/
> ------------------------------------------------------------------------
> *Academy of Natural Sciences of Drexel University, Philadelphia*
> /callomon at ansp.org Tel 215-405-5096 - Fax 215-299-1170/
>


-- 
Dirk Neumann

Tel: 089 / 8107-111
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---------

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Tel: +49-89-8107-111
Fax: +49-89-8107-300
email: Dirk.Neumann(a)zsm.mwn.de

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