[Nhcoll-l] Humidity in collection rooms

Fri Jun 25 10:35:22 EDT 2021

When I used to work at the NHM, London (mists of time!), we used to keep RH level above 50%, usually 55-60% maximum.  Too high and you get mouldy labels if they’re on the jar exterior (they shouldn’t be) and too low exacerbates evaporation and possible fire risk (sparking).  Although I did try a controlled experiment one really hot day to see if this was so - nothing.  Still, it keeps to the Health & Safety regulations.

With all good wishes, Simon

Simon Moore MIScT, RSci, FLS, ACR
Conservator of Natural Sciences and Cutlery Historian,

www.natural-history-conservation.com

> On 25 Jun 2021, at 15:19, <A.J.van_Dam at lumc.nl> <A.J.van_Dam at lumc.nl> wrote:
> 
> Dear Tonya,
> 
> We store our fluid preserved collections between RH 40-60% not being much concerned about the RH fluctuations as long as they fall within this range. 
> 
> To my opinion, constant temperature is the most important climate condition for fluid preserved specimens. Even small fluctuations can already lead to pressure fluctuations inside the jar due to the different expansion rates between the fluid components and container materials, which can easily lead to failure of the seal and increased fluid loss. Changes in temperature might also have impact on the solubility equilibrium of the dissolved fats and minerals, which might lead to coagulation/precipitation at low temperatures. Therefore, we try to keep the temp. of our fluid collections as constant as possible within the range of 18-22 °C.
> 
> Our dry collections are stored between 16-22 °C and RH 48-55% (max fluctuation: 3 units per day, 2 units per hour). This is the range advised by the Dutch Heritage Agency. 
> 
> It might well be that for antipodes other standards apply... 😉
> 
> Kind regards,
> 
> Dries
> 
> Andries J. van Dam | conservator
>  
> Museum of Anatomy | Leiden University Medical Center | Building 3 (V3-32)
> P.O.Box 9600 | 2300 RC Leiden | The Netherlands
> Visiting address: Hippocratespad 21 | Tel: +31 (0)71 52 68356 | E-mail: A.J.van_Dam at lumc.nl
>  
> Scientific associate | Natural History Museum London | http://www.nhm.ac.uk
> Van: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> namens Dirk Neumann <neumann at snsb.de>
> Verzonden: vrijdag 25 juni 2021 13:55:18
> Aan: nhcoll-l at mailman.yale.edu
> Onderwerp: Re: [Nhcoll-l] Humidity in collection rooms
>  
> Hi Lennart,
> 
> the recommended range is between 35-55% with daily fluctuations less than 5%. The closer you get to 60% (+/- 5% fluctuation), the closer you approach the threshold for potential mould outbreaks (depends on temperature and air circulation as well). A second think worth considering is metal corrosion, which is accelerated at a rH above 57% (and 18°C) as well.
> 
> The increased evaporation you mention likely is promoted by high air exchange rates, which basically hinders that an stable equilibrium can establish (thus the high technical need to actively control the parameters and keeping them stable even at aggressive air exchange rates).
> 
> With best wishes
> Dirk
> 
> 
> Am 25.06.2021 um 13:31 schrieb Hawks, Catharine:
>> I suspect that the decision would lie with whatever authority has jurisdiction in terms of fire safety for your museum.
>>  
>> Cathy
>>  
>> From: Lennart Lennuk <Lennart.Lennuk at loodusmuuseum.ee> 
>> Sent: Friday, June 25, 2021 7:26 AM
>> To: Hawks, Catharine <HawksC at si.edu>; Anderson, Gretchen <AndersonG at CarnegieMNH.Org>; Haff, Tonya (NCMI, Crace) <Tonya.Haff at csiro.au>; nhcoll-l at mailman.yale.edu
>> Subject: RE: [Nhcoll-l] Humidity in collection rooms
>>  
>> External Email - Exercise Caution
>> Hi!
>>  
>> Understandable. If the possibility for arc spark has been removed and the room has good ventilation, is it then better to keep the humidity above 50%?
>>  
>> Best!
>> Lennart
>>  
>> From: Hawks, Catharine [mailto:HawksC at si.edu] 
>> Sent: Friday, June 25, 2021 2:17 PM
>> To: Lennart Lennuk <Lennart.Lennuk at loodusmuuseum.ee>; Anderson, Gretchen <AndersonG at CarnegieMNH.Org>; Haff, Tonya (NCMI, Crace) <Tonya.Haff at csiro.au>; nhcoll-l at mailman.yale.edu
>> Subject: RE: [Nhcoll-l] Humidity in collection rooms
>>  
>> Actually, one concern for alcohol collections is that given how poorly most jars seal, there is an appreciable quantity of alcohol vapor in the space. When the RH is below 40% it is easy to arc a spark just from static electricity, so somewhere above that usually recommended by our fire protection engineers.
>>  
>> Cathy
>>  
>> From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> On Behalf Of Lennart Lennuk
>> Sent: Friday, June 25, 2021 7:11 AM
>> To: Anderson, Gretchen <AndersonG at CarnegieMNH.Org>; Haff, Tonya (NCMI, Crace) <Tonya.Haff at csiro.au>; nhcoll-l at mailman.yale.edu
>> Subject: Re: [Nhcoll-l] Humidity in collection rooms
>>  
>> External Email - Exercise Caution
>> Hi!
>>  
>> Why the fluid collections ideal is 30% +/- 5%?
>> I though it would be good to keep it 50-60% for less evaporation.
>>  
>> Best!
>> Lennart
>>  
>> From: Nhcoll-l [mailto:nhcoll-l-bounces at mailman.yale.edu] On Behalf Of Anderson, Gretchen
>> Sent: Thursday, June 24, 2021 5:53 PM
>> To: Haff, Tonya (NCMI, Crace) <Tonya.Haff at csiro.au>; nhcoll-l at mailman.yale.edu
>> Subject: Re: [Nhcoll-l] Humidity in collection rooms
>>  
>> Hi Tonya,
>> 
>> There is some flexibility in this, depending on the relative humidity that you can safely maintain, both physically and financially.  Remember that stability is extremely important.
>> 	• For study skins, we aim for 50% +/- 10%.  That allows for limited seasonal drift for those of us who live in extreme climates.  – your 45% set point falls within that, and should be ok.
>> 	• For fluid (ETOH etc) collections, the ideal should be much dryer. 30% +/- 5%. 
>> 
>> Good Luck. 
>> Gretchen Anderson
>>  
>> Gretchen Anderson
>> Conservator
>> Carnegie Museum of Natural History
>> 5800 Baum Blvd. 
>> Pittsburgh, PA 15213
>> Andersong at CarnegieMNH.org
>> (412)665-2607
>>  
>>  
>> From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> On Behalf Of Haff, Tonya (NCMI, Crace)
>> Sent: Wednesday, June 23, 2021 9:14 PM
>> To: nhcoll-l at mailman.yale.edu
>> Subject: [Nhcoll-l] Humidity in collection rooms
>>  
>> Hello all,
>>  
>> I am hoping that some of you can give me feedback on the relative humidity set point that is best for collection vaults with study skins, and for ETOH vaults. Right now we are planning on a 45% relative humidity in the study skin vaults, and 50% in the ETOH vault, but I wonder if 45% might be a bit dry for study skins? I would be grateful for any feedback!
>>  
>> Cheers,
>>  
>> Tonya
>>  
>> ---------------------------------------------------------
>> Dr Tonya Haff
>> Collection Manager
>> Australian National Wildlife Collection
>> National Research Collections Australia, CSIRO
>> Canberra, Australia 
>> Phone: (+61) 02 6242 1566 (office)
>> (+61) 0419 569 109 (mobile)
>>  
>> 
>> 
>> 
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> Natural History Collections (SPNHC), an international society whose
> mission is to improve the preservation, conservation and management of
> natural history collections to ensure their continuing value to
> society. See http://www.spnhc.org for membership information.
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