--- On Tue, 6/13/17,  <[email protected]> wrote:

> ------------------------------
>
> Subject: [Consdistlist] consdistlist
> Digest, Vol 31, Issue 46:  5.
>     Cold storage for
> nitrate negatives (Amy Minger)

> Amy Minger said:
> 
> "We recently purchased a commercial
> grade freezer to utilize as cold storage for nitrate
> negatives .......runs a defrost cycle every 6
> hours.......The max temperature was recorded as 19.73
> degrees Fahrenheit, and the max RH was recorded as
> 92.33%.........how did you address these concerns?"
> 

I think the issue here is having an auto-defrost cycle on your freezer. The 
freezer will cycle through higher temperatures in order to get rid of frost 
build up, which in turn will cause changes in humidity. You are better off not 
having a defrost cycle on your freezer and only defrosting it manually when it 
becomes necessary.
If you have a freezer that keeps a steady temperature (i.e. Non-self 
defrosting) at -20 or below, it will be better for the artefact and more stable 
with the humidity. If possible, you might want to disable the auto defrost 
function.
 If you have lower humidity in the room that the freezer is in, you will get 
less frost build up, and have fewer maintenance days defrosting the freezer.
That's my 2 cents.

Valerie Tomlinson
Conservator
Auckland Museum

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