I placed a HOBO temp/RH recording device in the collection space, and after several hours it read 73.1 degrees and 59% RH (a perfectly terrible combination!). We've since called Facility Operations to adjust the settings on the HVAC unit to 62 degrees and 40% or lower RH. Hopefully this can be acheived in the next few days-we'll see.
Here are my suggestions.
Optimum temperature and relative humidity (RH) levels are both issues of balancing of reasons for wanting lower with reasons for wanting higher levels.
For temperature the most important factors are wanting temperatures to be low enough to reduce (or eliminate) the risk of insect pest damage (and, to a less degree, chemical aging reactions such as oxidation and hydrolysis). This is balanced by wanting a temperature high enough to permit work to be done in the collection area without undue discomfort to collection workers. Obviously it is better if most collection work can be done in laboratories or examination rooms that are kept warmer than the collection area but there will still need to be some filing and organizing work done in the collection areas. A temperature specification of 60°F should preclude rapid development of pest infestations. A specification of +/- 2°F should be easy to achieve with modern equipment.
For RH level, the most important factors want levels to be low to retard insect pest activity, reduce chemical reactions such as hydrolysis and oxidation, reduce corrosion of vulnerable pins, etc. The practical limits to low RH levels are human comfort, possible static electricity problems and the cost of controlling below a certain level. Specifications for set point and allowable fluctuations and variations will require assessment of the collection, local climate, and HVAC equipment by a preventive conservation specialist.
Hope that helps,
Based on my personal experience (Antherenus is ubiquitous in the dryer areas of the SW USA, and definitely so here in Phoenix, AZ), dermestids are not very active (i.e. feeding/breeding/molting) until the temperatures reach the low '70s F. In the winter, I keep my collection at 65F and see no evidence of dermestid activity until late spring when indoor temps hit the low to mid-70's. You may want to do some testing for pests in your area, as the differences in cost to cool a collection in summer from 60 to 65F is substantial. (It's a bit less of a problem keeping things cool in Ottawa than KC!) Keeping the humidity low (single digits to low double digits--no problem here!) eliminates most other pests (e.g. psocoptera) and molds.
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Last modified on Tuesday, 12 November 2019