In general, cooler temperatures are preferred over warmer temperatures for the storage of most natural history collections (because at cooler temperatures the processes of deterioration and level of pest activity are reduced).� However, there are some important caveats:<br>
<br>Keeping fluid collection storage a few degrees cooler than the lab in which the containers are sealed is a good idea, because the cooler storage temperatures will improve the seals on the containers by creating negative pressure inside the containers.� However, keeping storage much colder than the lab where the specimens will be used is not such a good idea:<br>
*Temperatures below about 15C cause problems with fluid preservatives--alcohols tend to layer (particularly isopropyl), formaldehyde begins to precipitate out as paraformaldehyde (indicated by a whitish cloudiness in the fluid), dissolved lipids will congeal, some compressible gaskets will lose regain and therefore permit some evaporation, and so on.<br>
*On the other hand, at warmer temperatures, the processes of deterioration go faster (e.g., extraction of lipids and proteins in alcohol) and evaporation rates are higher.� <br>*Based on the above considerations, the ideal range for fluid collection storage is around 18C, but certainly no lower than 15C.<br>
<br>Lowering the storage temperature below flash point of the preservatives is not a good idea:<br>*To begin with, this is a theoretical idea, not a practical one (we have no evidence that a sub-flash point temperature will really reduce fire danger in a museum storage situation of containers of fluid preserved specimens on shelving in a controlled storage area).� <br>
*A container of fluid-preserved specimens sitting on a shelf in storage will not catch fire all by itself--an ignition sources is required.� Assuming that the ignition source is a fire in the storage area, then the temperature in the room is not likely to remain below flash point when there is a fire anyway--fire generates heat, so spending a lot of money to cool the entire storage area below flash point is pointless.<br>
*As Doug stated, cooler temperatures are much, much more expensive to maintain, and depend on functioning, reliable HVAC equipment.� Its not a wise use of resources.<br>*For fire safety, you are much better served by eliminating ignition sources in collection storage and installing a wet-pipe sprinkler system.� To reduce ignition sources, do not permit electrical outlets in storage, use safety switches and non-sparking light fixtures, do not store other materials with the specimens, use metal shelving, etc.<br>
*Temperatures below flash point will cause the above listed problems with preservative solutions.� When a container at around 15C is taken into a warmer lab and opened, the precipitated paraformaldehyde will leave the container as formaldehyde gas as the container warms up, which creates a serious health hazard for the human using the specimens.� <br>
*As Simon mentioned, changing temperature changes relative humidity.� By excessively cooling the air coming into storage, you may create a relative humidity problem where you did not have one before.<br><br>Finally, some caveats concerning an ideal temperature of 18C:<br>
*A realistic storage temperature for the collection depends on several factors because it must be a set point that is achievable without major expense, must be a temperature that can be maintained with only minor fluctuations, and may vary during the year.� <br>
*Storage temperatures can be made more stable by such things as locating storage in interior rooms (with no outside walls or windows), and by selecting set points� that are in keeping with the outside air temperature, building type, and HVAC system.� *Transitioning slowly between a warmer summer set point and a cooler winter set point in a temperate environment will produce a better storage environment than spending vast resources trying to maintain some arbitrary set point that exceeds the ability of your building, HVAC, and local climate to maintain.<br>
<div class="gmail_quote"><br>--John<br><br>John E. Simmons<br>Museologica<br>128 E. Burnside Street<br>Bellefonte, Pennsylvania 16823-2010<br><a href="mailto:simmons.johne@gmail.com" target="_blank">simmons.johne@gmail.com</a><br>
303-681-5708<br><a href="http://www.museologica.com" target="_blank">www.museologica.com</a><br>and<br>Adjunct Curator of Collections<br>Earth and Mineral Science Museum & Art Gallery<br>Penn State University<br>University Park, Pennsylvania<br>
and<br>Lecturer in Art<br>Juniata College<br>Huntingdon, Pennsylvania<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff"><div><font face="Arial"></font>�</div>
<blockquote style="BORDER-LEFT:#000000 2px solid;PADDING-LEFT:5px;PADDING-RIGHT:0px;MARGIN-LEFT:5px;MARGIN-RIGHT:0px" dir="ltr"><div><div class="h5">
<div style="FONT:10pt arial">----- Original Message ----- </div>
<div style="FONT:10pt arial;BACKGROUND:#e4e4e4"><b>From:</b>
<a title="marce_irene@yahoo.com.ar" href="mailto:marce_irene@yahoo.com.ar" target="_blank">Marcela Cosarinsky</a> </div>
<div style="FONT:10pt arial"><b>To:</b> <a title="nhcoll-l@mailman.yale.edu" href="mailto:nhcoll-l@mailman.yale.edu" target="_blank">nhcoll-l@mailman.yale.edu</a> </div>
<div style="FONT:10pt arial"><b>Sent:</b> Thursday, March 14, 2013 4:12
PM</div>
<div style="FONT:10pt arial"><b>Subject:</b> [Nhcoll-l] optimal
temperature</div>
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<td style="FONT-FAMILY:arial;FONT-SIZE:10pt">Hi All,<br>What
temperature would you recommend for the best
conservation of biological collections kept in
liquids (alcohol, formalin), squeletons and
embalmed animals? <br><br>
<div>Many thanks, Marcela</div>
<div><br></div>
<div>Marcela Cosarinsky (Curator)</div>
<div>Sala de Colecciones - Departamento de
Biodiversidad y biolog�a Experimental</div>
<div>Facultad de Cs. Exactas y Naturales</div>
<div>Universidad de Buenos Aires</div>
<div>Argentina</div>
<div>email:
<a href="mailto:marce_irene@yahoo.com.ar" target="_blank">marce_irene@yahoo.com.ar</a></div></td></tr></tbody></table></div></td></tr></tbody></table></div></td></tr></tbody></table></div>
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