[NHCOLL-L:2434] Re: Evaporation, taping of jars

[Gayle]

Hi NHCOLL-L,   I think my notes to Paul Calloman both bounced from the list.   I am resubmitting them here in case they are of interest to any of you.  (See Paul's responses below)

#1.  Hi NHCOLL-L folks and Paul,
    I have used Teflon tape to seal glass jars filled with 5% Formalin in
seawater & algae for 35 years now with no leakage.  I run the tape around
the screw threads of the glass jar twice and then screw the lid (generally
bakelite so they don't rust) down over them.  It seems to work fine.
However, everytime you unscrew the jar, you have to add more tape.    Is
this how you are using it?
    I have heard that the Teflon jar cap liners (quite expensive) work just as
well -- but they are out of my budget.

Gayle Hansen
Hatfield Marine Science Center
Oregon State University
Newport, Oregon 97365


#2.  Hi Paul,
    I have tried it both ways.  Without the tape, the formaldehyde often leaks out of the jars and the specimens dry out or rot.  With the tape, it keeps the specimens in good shape and the fluid level normal.  I used the old white teflon pipe threading tape for my collections.  Is that the same as you use?  (this may be thicker or less porous than the newer tapes)
    Dealing with alcohol may be a different problem than formaldehyde -- though the latter is a pretty small molecule.  .

Gayle

PS.  I am talking about glass bottles -- all sizes -- but all with bakelite or plastic lids.  Due to the seawater, I never used metal lids.    (Added here -- All of my jars do have thick coated paper liners -- I have never tried it without -- so I am not sure where the seal takes place.)

----- Original Message -----
From: "Paul Callomon " <callomon at acnatsci.org>
To: <gaylehansen at harborside.com>; <dwood at sdnhm.org>
Cc: <NHCOLL-L at lists.yale.edu>
Sent: Monday, September 27, 2004 1:55 PM
Subject: [NHCOLL-L:2433] Re: Evaporation, taping of jars


> Hi Gayle,
>
> Plumbers' tape is supposed to be applied to threads before a joint is
closed. As the joint is screwed shut, the tape 'smears' and fills the fine
gaps on the non-pressure-bearing face of the thread. It is good enough at
this to make water- and even gas-tight joints (though it's not approved for
domestic gas, for which liquid compound is used). It should not work on
glass jars, though, as the gaps in the threads are in the order of hundreds
of microns, rather than tens. Pipe threads with tape are themselves
impermeable, whereas the threads on a glass jar are just a mechanical device
to push the sealing disk down against the rim.
> In our collection, however, the tape was wrapped around the outside of the
jars. Teflon tape stretches slightly and wets any smooth surface, so at
first glance this gives the impression of a good seal. Any proud
irregularity (one that sticks out of the surface, like a molding rib, as
opposed to a pit or scratch), however, cannot be sealed by a tape that is
stretched over it, unless the tape were somehow capable of expanding at
right angles to the direction of stretch. Of course, though, when you
stretch tape its width contracts. This is why I think a non-stretched tape
with an adhesive that fills gaps (such as medical sticky bandage) will work
much better.
> I suspect your good results have more to do with the quality of your
primary seal (within the lid) than the application of tape to the threads.
You can find out; remove the sealing disk from a lid, and then screw it back
on with just the tape. If the fluid does not evaporate, your tape is
sealing. If it evaporates more slowly than a jar with no disk and no tape,
then the tape is sealing partially.
>
> Regards,
>
> PC.
>
>
> Paul Callomon
> Collections Manager
> Malacology, Invertebrate Paleontology and General Invertebrates
> Department of Malacology
> Academy of Natural Sciences
> 1900 Parkway, Philadelphia PA 19103-1195, USA
> Tel 215-405-5096
> Fax 215-299-1170
> Secretary, American Malacological Society
> On the web at http://erato.acnatsci.org/ams/
>
>
> >>> "Gayle" <gaylehansen at harborside.com> 09/27/04 02:08PM >>>
> Hi folks,
>
> I have used Teflon tape to seal glass jars filled with 5% Formalin in
> seawater & algae for 35 years now with no leakage.  I run the tape around
> the screw threads of the glass jar twice and then screw the lid (generally
> bakelite so they don't rust) down over them.  It seems to work fine.
> However, everytime you unscrew the jar, you have to add more tape.    Is
> this how you are using it?
>
> I have heard that the Teflon jar cap liners (quite expensive) work just as
> well -- but they are out of my budget.
>
> Gayle Hansen
> Hatfield Marine Science Center
> Oregon State University
> Newport, Oregon 97365
>
>
> ----- Original Message -----
> From: "Paul Callomon " <callomon at acnatsci.org>
> To: <dwood at sdnhm.org>
> Cc: <NHCOLL-L at lists.yale.edu>
> Sent: Monday, September 27, 2004 10:25 AM
> Subject: [NHCOLL-L:2431] Re: Evaporation, taping of jars
>
>
> > Hi Dustin,
> >
> > My predecessor as collections manager spent months wrapping plumbers'
tape
> (Teflon tape) round each of about 25,000 jars in our alcohol collection.
> Unfortunately, she did not check the condition of the lids first, and I
have
> found dozens of old metal lids happily rusting away under their bright new
> tape covering.
> > As far as I can tell, taping up jars in this way does not help much. If
> vapor has made it past the initial seal, then tape may or may not trap it
> The principle is that the tape provides a secondary barrier to vapor
escape,
> but this assumes a very clean, tight seal against both the jar (which must
> thus be free of molding marks) and the lid (which should thus not be
> knurled). In practice, most collections contain a combination of lid and
jar
> types. For us, any reduction in vapor release that taping might have
> achieved has not justified the considerable time taken to apply the tape
and
> the difficulty I now have in visually assessing the condition of older
metal
> caps. Instead, I have bought a big box of new lids in each of the sizes we
> use, and apply these to older jars every time I find one that is leaking.
> > I guess if you used a tape whose adhesive had good bridging qualities,
> such as medical adhesive bandage (which we use for jar labels, with great
> success), then taping up lids would work better.
> >
> > Regards,
> >
> > PC.
> >
> > Paul Callomon
> > Collections Manager
> > Malacology, Invertebrate Paleontology and General Invertebrates
> > Department of Malacology
> > Academy of Natural Sciences
> > 1900 Parkway, Philadelphia PA 19103-1195, USA
> > Tel 215-405-5096
> > Fax 215-299-1170
> > Secretary, American Malacological Society
> > On the web at http://erato.acnatsci.org/ams/
> >
> >
> > >>> "Dustin Wood" <dwood at sdnhm.org> 09/21/04 05:37PM >>>
> > Dear Paul Callomon,
> > I got your email off the nhcoll-list serve from a discussion on taping
the
> > outside of fluid-filled jars to take an extra step in preventing
> > evaporation.  I'm interested in the product you use for sealing the
> outside
> > of the jars?  I've noticed some evaporation on some of our new jars/lids
> > (even with foam-backed Teflon liners) and would like to take the extra
> > precaution.  Thanks in advance for your help.
> >
> > Dustin
> >
> >
> > Dustin Wood
> > Collections Manager
> > Department of Herpetology
> > San Diego Natural History Museum
> >
> > 1788 El Prado
> > San Diego, CA 92101
> >
> > Phone: 619.255.0305
> > FAX: 619.232.0248
> > Email: dwood at sdnhm.org
> >
> >
>

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