[Nhcoll-l] PTFE tape on jars

[John E Simmons]

Dirk,
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.

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?

The Teflon liners should work well--we can purchase several sizes of jar
lids here with Teflon liners already in them.

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:
http://www.dowcorning.com/content/discover/discoverchem/si-release.aspx?e=How+Silicones+Work

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.

--John

On Mon, Jan 13, 2014 at 2:18 AM, Dirk Neumann <dirk.neumann at zsm.mwn.de>wrote:

>  Dear Paul,
>
> we had bad results with PTFE tape because it didn't seal jars adequately
> even though tied thoroughly around the lids.
>
> 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.
>
> 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).
>
> http://www.taxidermy.ch/p078000003.html?article_id=78000164&shop_action=detail
>
> 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.
>
> 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).
>
> Hope this offers some ideas ...
>
> All the best
> Dirk
>
> Am 10.01.2014 22:48, schrieb Callomon,Paul:
>
>  Folks,
>
>
>
> 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.
>
> 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.
>
>
>
>
>
> *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 <callomon at ansp.org> Tel 215-405-5096 <215-405-5096> -
> Fax 215-299-1170 <215-299-1170>*
>
>
>
>
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> --
> Dirk Neumann
>
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> ---------
>
> Dirk Neumann
>
> Tel: +49-89-8107-111
> Fax: +49-89-8107-300
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>
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>
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> natural history collections to ensure their continuing value to
> society. See http://www.spnhc.org for membership information.
>
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