[Nhcoll-l] Phenolic lids in alcohol

[Dirk Neumann]

... just to add to Catharine Hawks:

phenolic plastic is a phenol formaldehyde resin plastic belonging to the 
group of thermosetting polymers such as Bakelite. In general, all 
plastics based on formaldehyde polymers / using formaldehyde for 
condensation of the polymer chains have issues if coming into secondary 
contact with free formaldehyde after polymerisation, which induces 
breaking of polymer chains. In specimen jars with (initially) formalin 
fixed material this may be leaking residual formalin escaping from 
specimens, as Catharine already said.

All plastics belonging to this group of thermosetting polymers should be 
avoided in (wet) collections. If plastic can be avoided, LDPE / HDPE (= 
Low/High Density Polyethylen) should be preferred, as PE-Plastic are the 
most stable plastics we have for collections (Polypropylene & PVC may 
also cause issues depending on how the collection is / has to be 
maintained).

All the  best
Dirk



Am 16.06.2014 01:26, schrieb CAHawks at aol.com:
> One problem with phenolic caps is that the polymer probably contains 
> formaldehyde. Exposed to trace formaldehyde from fixation of specimens 
> subsequently stored in alcohol, the polymer will deteriorate (that 
> old, "like dissolves like" concept). Any specimen fixed in formalin 
> and later transferred to alcohol should have some unfixed formaldehyde 
> in the alcohol given that fixation is a equilibrium reaction.
> Cathy
> Catharine Hawks, PA-AIC, FIIC
> Conservator, NMNH
> (h) 703.876.9176
> (o) 202.633.0835
> mobile 703.200.4370
> moblile 202.701.8458
> hawksc at si.edu
>
> In a message dated 6/13/2014 5:22:28 P.M. Eastern Daylight Time, 
> halford at sfu.ca writes:
>
>     When phenolic capped vials are stored as you describe the caps can
>     expand over time and eventually fall off, potentially leading to
>     lots becoming mixed in the bottom of the holding vessel.  It's
>     better to discard the cap and replace it with a loose plug of
>     cotton.  Face the neck of the vial up so no air bubbles become
>     trapped.
>
>     Steve.
>
>     Steve Halford (halford at sfu.ca <mailto:halford at sfu.ca>)
>     Museum Technician (Retired)
>     Department of Biological Sciences
>     Simon Fraser University
>
>
>
>     On Fri, Jun 13, 2014 at 10:28 AM, Callomon,Paul <prc44 at drexel.edu
>     <mailto:prc44 at drexel.edu>> wrote:
>
>         Folks,
>
>         We have noticed that in cases where a phenolic resin cap is
>         immersed in alcohol (70-80% ethanol) for long periods (such as
>         when a vial with a sample is included in a larger
>         alcohol-preserved lot) the alcohol becomes discolored. I
>         presume the resin is leaching something. Does anyone know of
>         any published work on this?
>
>         *Paul Callomon*
>         /Collection Manager, Malacology, Invertebrate Paleontology and
>         General Invertebrates/
>
>         ------------------------------------------------------------------------
>
>         *Academy of Natural Sciences of Drexel University, Philadelphia***
>
>         1900 Benjamin Franklin Parkway, Philadelphia PA 19103-1195, USA
>         /callomon at ansp.org <mailto:callomon at ansp.org> Tel 215-405-5096
>         <tel:215-405-5096> - Fax 215-299-1170 <tel:215-299-1170>/
>
>
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-- 
Dirk Neumann

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