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<div class="moz-cite-prefix">Morning John!<br>
<br>
I think (personal impression rather than something I could proof)
that deterioration follows the concept "similar dissolves in
similar" (I am not sure if this literally translation of the
German "Ähnliches löst sich in Ähnlichem" is common in English,
too):<br>
<br>
Parafilm is a polyolefin wax which is not that stable against
organic solvents, my impression is that if parafilm gets into
contact with long-chained hydrophobic hydrocarbonates, especially
vaseline / petroleum jelly, the parafilm wax starts to "melt" and
turns into a smeary waxy stringing substance. This type of
deterioration is also observed in combination with vacuum greases.<br>
<br>
PTFE tape: we have a type of jar without threads, for these PTFE
tapes failed completely. For use in combination with metal lids /
threaded jars (as long as there is no way to get hold of the
acid-resistant type of metal lids which have stronger liners), I
would prefer the teflon inlays which also protects the lid against
corrosion / chemical reactions triggered from condensation inside
the jar.<br>
<br>
Removal of old silicone grease: thanks for pasting Simon's very
valuable link into this discussion! I never used silicon based
greases in the collection after devastating results from my
initial testing with various vacuum greases (dumping a chunk of
the grease into our denatured alcohol and comparing stability
after 1 year). Since then, I always use ("my" most favoured and
most appreciated) Alsirol grease produced by a small company in
Bamberg, Germany. Just hope they will never run out of production,
but as this fat is food safe and of prevailled usage in small
scale breweries in Upper Franconia, I am confident ;-)<br>
<br>
To remove old silicone glue, you may also use (quite drastic, but
works just fine) a drilling machine with a soft & fine
brass-brush-attachment turning at moderate speed. Tried this
methods with large old battery jars with good results after
receiving this tip from aquarium hobbyists cutting &
re-glueing large tanks. One needs to be well skilled in free-hand
operating of drilling machines, especially in combination with
fragile glass containers, of course, but it works pretty well and
is very time efficient. <br>
<br>
All the best<br>
Dirk<br>
<br>
<br>
Am 13.01.2014 18:43, schrieb John E Simmons:<br>
</div>
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cite="mid:CAF7GCDbqAhFuiVvPeU67QFO4ORNxufJf-Hi1d_Cbh-f1B6rg+w@mail.gmail.com"
type="cite">
<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 moz-do-not-send="true"
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 moz-do-not-send="true"
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 moz-do-not-send="true"
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,</p>
<p class="MsoNormal"> </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. </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.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"> </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=""></span></p>
<div class="MsoNormal"
style="text-align:center;background:white"
align="center"> <span
style="font-size:10.0pt">
<hr size="2" width="100%" align="center"> </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"></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 moz-do-not-send="true"
href="mailto:callomon@ansp.org"
target="_blank"><span style="color:blue">callomon@ansp.org</span></a>
Tel <a moz-do-not-send="true"
href="tel:215-405-5096"
value="+12154055096" target="_blank">215-405-5096</a>
- Fax <a moz-do-not-send="true"
href="tel:215-299-1170"
value="+12152991170" target="_blank">215-299-1170</a></i></span><span
style="font-size:12.0pt"></span></p>
<p class="MsoNormal"> </p>
</div>
<br>
<fieldset></fieldset>
<br>
</div>
</div>
<div class="im">
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Dirk Neumann
Tel: 089 / 8107-111
Fax: 089 / 8107-300
email: Dirk.Neumann(a)<a moz-do-not-send="true" href="http://zsm.mwn.de" target="_blank">zsm.mwn.de</a>
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Dirk Neumann, Section Ichthyology / DNA-Lab
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81247 Munich (Germany)
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NHCOLL-L is brought to you by the Society for the
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society whose<br>
mission is to improve the preservation, conservation and
management of<br>
natural history collections to ensure their continuing
value to<br>
society. See <a moz-do-not-send="true"
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<pre class="moz-signature" cols="72">--
Dirk Neumann
Tel: 089 / 8107-111
Fax: 089 / 8107-300
email: Dirk.Neumann(a)zsm.mwn.de
Postanschrift:
Staatliche Naturwissenschaftliche Sammlungen Bayerns
Zoologische Staatssammlung München
Dirk Neumann, Sektion Ichthyologie / DNA-Labor
Münchhausenstr. 21
81247 München
Besuchen Sie unsere Sammlung:
<a class="moz-txt-link-freetext" href="http://www.zsm.mwn.de/ich/">http://www.zsm.mwn.de/ich/</a>
---------
Dirk Neumann
Tel: +49-89-8107-111
Fax: +49-89-8107-300
email: Dirk.Neumann(a)zsm.mwn.de
postal address:
Bavarian Natural History Collections
The Bavarian State Collection of Zoology
Dirk Neumann, Section Ichthyology / DNA-Lab
Muenchhausenstr. 21
81247 Munich (Germany)
Visit our section at:
<a class="moz-txt-link-freetext" href="http://www.zsm.mwn.de/ich/">http://www.zsm.mwn.de/ich/</a>
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