Medium density fiberboard

Harriet Woolmore <harriet.woolmore [at] cls__glasgow__gov__uk> writes

>It is my understanding that MDF (Medium Density Fibre board) is not
>used in museums in the United States of America for both
>conservation and health and safety reasons. At Glasgow Museums,  MDF
>is widely used both in the construction of and as dress panels
>inside display cases. ...

I'm sure we will hear a lot about the chemical dangers of MDF off
gassing, but I've noticed that other aspects of MDF board can also
be problematic when used in museum cases:

MDF is porous. This makes unsealed MDF not suitable for extremely
well sealed cases. My understanding is that a well sealed case
utilising some walls of MDF (instead of glass) can be substantially
more "leaky" than a glass only case of exactly the same
construction. Apparently MDF is handled in fabrication shops by
using vacuum suction cups, and the material is so porous that three
or more sheets can be carried at once using suction applied to one
surface only.

MDF can transfer moisture. As the material is porous, and as it
seems to have an affinity for moisture, I suspect it can efficiently
"wick" moisture from one environment to another. This could mean
that a dry ventilated lightbox or damp open area on the outside of
an MDF wall could affect the case interior rather easily. A high
vapour pressure differential would force moisture through the MDF.

MDF holds moisture, as does any wood or composite product. The good
news would be that it is a stable moisture mass, the bad news is
that it needs time for the relative humidity to acclimatise to the
proper level. It may also other things, like nasty chemicals, until
conditions change.

I suggest that if MDF is used, the inner surface should be sealed
with an aluminum foil type barrier film. This is quite easily done
by simple ironing the film to the surface of the board with a
household iron. Mitsubishi's aluminum foil film and Marvelseal film
are two suitable choices. More information on the film is available
at <URL:http://www.keepsafe.ca>

Jerry Shiner
Keepsafe Systems
800-683-4696


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                  Conservation DistList Instance 17:4
                   Distributed: Monday, June 23, 2003
                        Message Id: cdl-17-4-013
                                  ***