|
Humidity and Temperature
In an ideal world...
The levels of relative humidity—RH—recommended for the safe-keeping of collections in museums, galleries and libraries are:
-
50% ± 5%;
-
this is a compromise which has been arrived at by assessing the average requirement of an average collection in an average climate;
-
it is almost impossible to achieve a constant relative humidity of 50%; so a margin of 5 per cent either side of this has been permitted, that is, between 45% and 55%;
-
the danger zones for relative humidity are over 65%, when mould grows and metal corrosion is common; and below 35%, when some materials dry out and become brittle;
-
in tropical areas, 60% ± 5% is more realistic.
For the safe-keeping of collections in museums, galleries and libraries, the temperature should be kept constant—in the range 18–220C.
These recommended levels are ideal. However, in some areas of Australia it is extremely difficult to come close to achieving these recommended levels. It is not always practical to put all our efforts into achieving these levels within a building, when there are many others ways of providing protection.
| CAUTION: |
|
We're not in an ideal world, so it is important to remember that many objects become conditioned to their environments—even though these may be extreme.
A lot of damage can be done by attempting to place an object, which is stable in an extreme climate, into an environment that conforms to the recommended levels.
|
|
