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<div class="moz-cite-prefix">Hi Tonya & Lennart,</div>
<div class="moz-cite-prefix"><br>
</div>
<p>I guess there are several layers to unfold here:</p>
<p>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. <br>
</p>
<p>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.</p>
<p>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. <br>
</p>
<p>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.</p>
<p>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.</p>
<p>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:
<a class="moz-txt-link-freetext" href="https://pharma.stoelzle.com/en/product_category/weithalsglaser/">https://pharma.stoelzle.com/en/product_category/weithalsglaser/</a> <br>
</p>
<p>So as mostly no clear cut answer, but hopefully one that is
useful.</p>
<p>All the best</p>
<p>Dirk<br>
</p>
<p> <br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">Am 20.11.2020 um 00:29 schrieb Haff,
Tonya (NCMI, Crace):<br>
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<p class="MsoNormal">Hi all,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">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!<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Cheers,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Tonya<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-AU">---------------------------------------------------------<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-AU">Dr
Tonya Haff<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-AU">Collections
Manager<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-AU">Australian
National Wildlife Collection<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-AU">National
Research Collections Australia, CSIRO<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-AU">Canberra,
Australia
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-AU">Phone:
(+61) 02 6242 1566 (office)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-AU">(+61)
0419 569 109 (mobile)<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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