[Nhcoll-l] Jar liners

[Dirk Neumann]

Hi Tonya & Lennart,

I guess there are several layers to unfold here:

Foamed liners - like the F217 liners you mention - consist of a foamed 
cell structure which - if the lid is screwed down tight - is compressed 
again the neck of the jar. This outs the cells under pressure and closed 
cells would withstand this tension better then open cell structures. It 
is hard to tell if the F217 liners you mention has open or closed cells, 
which gas is used for filling of the foam structure, etc. Even if the 
F217 liners would have the right composition, right thickness, closed 
cells - it still a is compressible gasket which has a limited life span.

To produce a good closure, you would further need to consider the 
threads on the jar (continuous or not), the composition of the lid 
itself (the best liner does not help if the plastic used for the lid 
itself is of poor quality, etc. Most important seems to me that sizes of 
such lids are standardised (rather then customised for specific jars), 
so that they can easily be replaced if they fail. This is one of the 
huge problems many collections with Copehagen jars now face after 
plastic lids reached the end of their life span, sized where customised, 
company went out of production: it is virtually impossible to replace 
these lids - which causes huge problems in many collections.

It seems that F217 and PTFE liners are often used as inlays for Phenolic 
caps (Bakelite) - which is a no-go in fluid collections because this 
sort of thermoset plastics is easily degraded by residual formaldehyde 
escaping from formaldehyde preserved specimens, even if they have been 
transferred in to alcohol. As said: the best liner is worthless if the 
plastic lid itself is unsuited.

In general, plastic lids are not a good oxygen barrier - this is also 
worth remembering, especially if specimens inside such jars release a 
lot of fats or oils.

Rather then concentrating on specific lids I would look into jars that 
are designed for the pharmaceutical sector. Here, both the jar 
(soda-lime glass) and the lid are expected (and usually tested) to 
withstand a wide range of chemicals AND to provide a good barrier 
against oxygen.

There are different suppliers of such jars, the disadvantage of the wide 
mouth jars however is that the largest opening in these jars is 65 mm. 
So a good option for for 100 - 1000 ml jars, but not for larger jars.  
Stölzle (who also produce high quality borosilicate stoppered jars) is a 
possible source for such jars, but there are many others as well: 
https://pharma.stoelzle.com/en/product_category/weithalsglaser/

So as mostly no clear cut answer, but hopefully one that is useful.

All the best

Dirk




Am 20.11.2020 um 00:29 schrieb Haff, Tonya (NCMI, Crace):
>
> Hi all,
>
> I know I’ve asked about this before, but may I please clarify again…. 
> Does anyone have preference regarding PTFE (e.g. Teflon, I believe) 
> lid liners vs F217 liners, which are layered polyethylene (as far as I 
> understand). Can anyone give me advice as to what would be better as a 
> lid liner for specimens kept in 70-90% EtOH? Advice very appreciated!
>
> Cheers,
>
> Tonya
>
> ---------------------------------------------------------
>
> Dr Tonya Haff
>
> Collections Manager
>
> Australian National Wildlife Collection
>
> National Research Collections Australia, CSIRO
>
> Canberra, Australia
>
> Phone: (+61) 02 6242 1566 (office)
>
> (+61) 0419 569 109 (mobile)
>
>
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-- 


Dirk Neumann

Tel: 089 / 8107-111
Fax: 089 / 8107-300
neumann(a)snsb.de

Postanschrift:

Staatliche Naturwissenschaftliche Sammlungen Bayerns
Zoologische Staatssammlung München
Dirk Neumann, Sektion Ichthyologie / DNA-Storage
Münchhausenstr. 21
81247 München

Besuchen Sie unsere Sammlung:
http://www.zsm.mwn.de/sektion/ichthyologie-home/

---------

Dirk Neumann

Tel: +49-89-8107-111
Fax: +49-89-8107-300
neumann(a)snsb.de

postal address:

Bavarian Natural History Collections
The Bavarian State Collection of Zoology
Dirk Neumann, Section Ichthyology / DNA-Storage
Muenchhausenstr. 21
81247 Munich (Germany)

Visit our section at:
http://www.zsm.mwn.de/sektion/ichthyologie-home/

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