<div dir="ltr"><div><div><div><div><div>Dirk,<br></div><div>Thanks for your contribution to this discussion. Just to be clear, the recommended use of PTFE tape is to wrap it around the threads on the jar before the lid is applied, in order to help the lid seal better with the jar. PTFE is less permeable to the transmission of oxygen than Parafilm.<br>
</div><br></div>I presume that the deterioration of parafilm that you describe is caused by contact with the old grease remaining on the glass? Do you have any idea what the chemical reaction is that causes the deterioration?<br>
<br>The Teflon liners should work well--we can purchase several sizes of jar lids here with Teflon liners already in them.<br><br></div>Concerning the removal of old silicon, Simon Moore pointed out to me that you can purchase a silicon releasing agent in liquid or spray form at many hardware stores in the US and the UK. These work with the methyl groups in silicon:<br>
<a href="http://www.dowcorning.com/content/discover/discoverchem/si-release.aspx?e=How+Silicones+Work">http://www.dowcorning.com/content/discover/discoverchem/si-release.aspx?e=How+Silicones+Work</a><br><br></div>Since Simon alerted me to the release agent, I have used the liquid form to remove old silicon seals from glass several times--you might want to try a silicon release agent on the silicon oil you mentioned.<br>
<br></div>--John<br><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Jan 13, 2014 at 2:18 AM, Dirk Neumann <span dir="ltr"><<a href="mailto:dirk.neumann@zsm.mwn.de" target="_blank">dirk.neumann@zsm.mwn.de</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div>Dear Paul,<br>
<br>
we had bad results with PTFE tape because it didn't seal jars
adequately even though tied thoroughly around the lids. <br>
<br>
Parafilm as Tony suggested works much better. You can easily
remove it residue-free again, but be careful if wrapping parafilm
around jars that are closed with ground stoppers / glass planes
& grease (e.g. old battery jars): the parafilm will dissolve
quickly into a rather sticky slime, which can hardly be removed.<br>
<br>
For twist-off jars with metal lids adding additional Teflon liners
to be inserted in the lids might be an idea: colleagues in
Switzerland use those with pretty good results for several years
now (the website is in German, they don't offer a English version,
sorry - But from the pictures you may get an idea what those
liners look like).<br>
<span><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)" lang="DE-CH"><a href="http://www.taxidermy.ch/p078000003.html?article_id=78000164&shop_action=detail" style="color:blue;text-decoration:underline" target="_blank">http://www.taxidermy.ch/p078000003.html?article_id=78000164&shop_action=detail</a></span></span>
<br>
<br>
I am not sure if these are available in the US, but these liners
not only seal but also protect metal lids against evaporating
moisture thus preventing them from rusting.<br>
<br>
For Le-Parfait jars etc. you can also add some high quality joint
grease - but be careful and avoid any silicon based vacuum grease
as it is nearly impossible to bring the silicon oil off the
glasses after the silicon grease deteriorated (which happens
within few years).<br>
<br>
Hope this offers some ideas ...<br>
<br>
All the best<br>
Dirk<br>
<br>
Am 10.01.2014 22:48, schrieb Callomon,Paul:<br>
</div>
<blockquote type="cite"><div><div class="h5">
<div>
<p class="MsoNormal">Folks,<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">At least 20 years ago (before my time
here), white plumbers’ tape was wrapped around the edge of the
lids and onto the sides of all the bottle and jars in a
certain section of our alcohol collections. This is the PTFE
tape that plumbers use to seal threads; it is thin, soft and
non-adhesive. Presumably the idea was to provide a secondary
vapor barrier in addition to the jar lid seal.
<u></u><u></u></p>
<p class="MsoNormal">We are now doing long-overdue major
maintenance on this collection, and are trying to assess the
efficacy of this tape. I’d be very interested to hear from
anyone who (a) has used it and can show it works (b) has used
it and can show it doesn’t work, or (c) who considered using
it but decided not to, and why.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal" style="background:white"><b><span style="font-size:10.0pt">Paul Callomon</span></b><span style="font-size:10.0pt"><br>
<i>Collection Manager, Malacology, Invertebrate Paleontology
and General Invertebrates</i></span><span style><u></u><u></u></span></p>
<div class="MsoNormal" style="text-align:center;background:white" align="center">
<span style="font-size:10.0pt">
<hr align="center" size="2" width="100%">
</span></div>
<p class="MsoNormal" style="background:white"><b><span style="font-size:10.0pt">Academy of Natural
Sciences of Drexel University, Philadelphia</span></b><b><span style="font-size:10.0pt"><u></u><u></u></span></b></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt">1900 Benjamin Franklin
Parkway, Philadelphia PA 19103-1195, USA</span><span style="font-size:10.0pt"><br>
<i><a href="mailto:callomon@ansp.org" target="_blank"><span style="color:blue">callomon@ansp.org</span></a>
Tel <a href="tel:215-405-5096" value="+12154055096" target="_blank">215-405-5096</a> - Fax <a href="tel:215-299-1170" value="+12152991170" target="_blank">215-299-1170</a></i></span><span style="font-size:12.0pt"><u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
<br>
<fieldset></fieldset>
<br>
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Dirk Neumann
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