[Nhcoll-l] FW: More on jars

Sun Nov 1 12:16:40 EST 2015

Hi Rob,

I have been in contact with Schott glass because of the problems we had 
with our historic specimen containers. This is very hard to evaluate, as 
the observed effects strongly depend on the glass composition of the 
respective jars, which, however, are rarely known. Same applies for the 
production details (too evaluate the amount of stress of the glass melt 
- e.g. if cooling was too fast).

As said before, I have some pictures on this (and a presentation) - 
might be worth to revisit  John Simmons excellent workshop on specimen 
containers ?

All the best
Dirk

Am 29.10.2015 um 21:48 schrieb Robert Waller:
>
> Hi Paul,
>
> Thanks for reminding me of those nice pictures.
>
> I wonder though how much the glass disease issue contributed to the 
> breakage. Although a little difficult to make out in the pictures it 
> looks like the surface alteration of the glass is still very thin in 
> relation to the bulk of the glass wall. If that is the case then it 
> might not be the most significant cause of fracture – perhaps thermal 
> stress from a manufacturing flaw or just past dropping contributed. 
> Have you ever seen comparable fractures in vials not exhibiting glass 
> disease? I suppose a 2x2 factor table relating count of fractured and 
> not fractured vials with and without glass disease would let us know. 
> Sounds like a counting job for an intern!
>
> Rob
>
> *From:* nhcoll-l-bounces at mailman.yale.edu 
> [mailto:nhcoll-l-bounces at mailman.yale.edu] *On Behalf Of *Callomon,Paul
> *Sent:* October 29, 2015 4:01 PM
> *To:* NH-COLL listserv (nhcoll-l at mailman.yale.edu) 
> <nhcoll-l at mailman.yale.edu>
> *Subject:* [Nhcoll-l] FW: More on jars
>
> Hi Rob,
>
> I’ve occasionally seen glass vials weakened to the point of fracture 
> by glass disease. We illustrated one in Collections Forum 26 (1-2): 
> 35, fig. 3.
>
> PC
>
> *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 <mailto:callomon at ansp.org> Tel 215-405-5096 - Fax 
> 215-299-1170/
>
> *From:*Robert Waller [mailto:rw at protectheritage.com]
> *Sent:* Thursday, October 29, 2015 3:46 PM
> *To:* Callomon,Paul; NHCOLL-L
> *Subject:* RE: [Nhcoll-l] More on jars
>
> Hi Paul,
>
> There is not really a “difference in pressure between the internal 
> structure of the glass and the external environment”. In both cases, 
> ambient RH or fluid preservative, alkali cations (Na^+ , Ca^+ ) are 
> leached out of the glass and replaced with H^+ from the water. There 
> will be a gradual migration of alkali cations toward the surface and a 
> gradual counter migration of H^+ inward (charge balance must always be 
> maintained). There is no “pressure differential” between outside and 
> inside of the glass – at least not due to alkali migration.
>
> Is it important at all?
>
> We are exchanging Na^+ , Ca^+ , from the glass in exchange for some 
> H^+ from the solution. But that is, after all, what a buffer would do 
> and we might choose to add a buffer purposely. I doubt there would be 
> a situation where a soda lime glass would raise the pH of a 
> preservative solution above neutral though I am open to being 
> corrected on that if I am wrong and someone knows better. Myself, I 
> don’t think that this source of preservative solution composition 
> alteration poses any significant risk to collection preservation.
>
> The glass jar is eroded and weakened and this could be a concern. 
> Still so long as the inside of the jar remains “wet” there will be a 
> layer of hydrated glass (like on a pH sensing electrode) that will 
> reduce the rate of reaction (like a tarnish layer can protect a 
> metal). I would be surprised if there were a case of glass jar failure 
> due to this cause, though again I am open to being corrected by anyone 
> with experience of such a failure.
>
> Best,
>
> Rob
>
> *From:* nhcoll-l-bounces at mailman.yale.edu 
> <mailto:nhcoll-l-bounces at mailman.yale.edu> 
> [mailto:nhcoll-l-bounces at mailman.yale.edu] *On Behalf Of *Callomon,Paul
> *Sent:* October 29, 2015 1:11 PM
> *To:* NH-COLL listserv (nhcoll-l at mailman.yale.edu 
> <mailto:nhcoll-l at mailman.yale.edu>) <nhcoll-l at mailman.yale.edu 
> <mailto:nhcoll-l at mailman.yale.edu>>
> *Subject:* [Nhcoll-l] More on jars
>
> Folks,
>
> So here’s a jar question that perhaps someone has answered:
>
> In “glass disease” the non-silicate components of, say, soda glass 
> gradually leach out of the silicate matrix and onto the surface as 
> hydrated compounds. This happens more where humidity is high, as water 
> is involved in the latter stages of the reaction. In vials found in 
> dry collections, the resulting compounds can be seen as droplets of 
> moisture on the surface of the glass. They will be on both the inside 
> and outside if the vial is only stoppered with cotton, allowing its 
> internal humidity to be close to ambient.
>
> Where the jar or vial is full of fluid, however, the values 
> representing the difference in pressure between the internal structure 
> of the glass and the external environment will differ between the 
> interior and exterior. So the question is: will the rate of migration 
> of the non-silicate compounds differ accordingly – that is, will they 
> tend head for the outside of the jar, where the pressure differential 
> is higher? The answer, if there is one, may have a bearing on the 
> extent to which glass deterioration will contaminate the fluid in the 
> jar.
>
> *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 <mailto:callomon at ansp.org> Tel 215-405-5096 - Fax 
> 215-299-1170/
>
>
>
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