Microclimate frames

David Frank Bugeja <david-frank.bugeja [at] gov__mt> writes

>There is considerable literature on microclimate frames, where the
>majority of the studies are carried out by conservation scientists
>and are mainly focused on theoretical aspects. Unfortunately,
>however, there is little information on how microclimate frames are
>actually made and which materials are being used. I am particularly
>finding it very difficult to obtain a list of sealing materials that
>are currently considered for microclimate frames.

The new Butterworths book on paintings conservation now scheduled
for publication in early 2012 contains a chapter which I wrote which
covers this topic.  The National Gallery of Victoria in Melbourne
Australia evolved a technology in the 1980's for housing paintings
in frames which incorporates optically coated glass placed in the
rebate of the frame- such as Denglas, Invisiglass and Mirogard--a
custom made stepped timber moulding is attached permanently attached
to the reverse of the frame using self drilling, self tapping
screws. A padded timber slip, which may be painted to gilded to
suit, is inserted, and the painting placed in the frame and secured
with metal clips screwed the middle step of the timber moulding.  An
insulated backing board using materials such as Fome-Cor, Corflute,
Alucobond or Dibond is the attached with screws to the last step of
the moulding.  This methodology can be used for paintings on rigid
supports as well as on canvas.  Care needs to be taken to assure
panel paintings on wood are free to move slightly in the cross grain
direction.

We applied this method en masse to a collection of about 3,000
paintings over several years to protect them in open display. It is
possible to totally seal a small panel painting using aluminium
extruded moulding and various double sided tapes or silicon
adhesives and this process is also described- however, daily changes
in air pressure put considerable strain on a thin, flat sealed box
like this and unless there is a compelling reason to totally seal
the system, it is not particularly advisable.  These packages also
become very heavy due to the thickness of glass required as the size
of the painting to be housed increases- and you have a fairly large
painting.  The process is difficult to describe in words, but
actually quite simple. A microclimate is created and this is easy to
monitor using humidity monitoring strips.

There are a number of variations of this method which adapt for
issues such a particularly dusty or moist environments and it is
important to think the process through carefully to take your
particular circumstances into account. This has been a very
successful preservation strategy over many years and I recommend you
consider it.

Thomas Dixon
former NGV Chief Conservator (retired)
Melbourne Australia


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                  Conservation DistList Instance 25:4
                   Distributed: Monday, June 27, 2011
                        Message Id: cdl-25-4-004
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