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.

Escal barrier film is a transparent high barrier film that has been
used in microclimate framing. Mitsubishi's aluminum foil film, a
very pliable barrier material that was favored by some, is no longer
in production.

I would also like to direct your attention to the Propaint project

    <URL:http://propaint.nilu.no>

The final report

    <URL:http://propaint.nilu.no/
        Portals/23/PROPAINT-Final%20Report.pdf>

contains a great deal of information on creating microclimate
frames, including illustrations of a number of differing designs.

One of this project's major concerns was the study of pollutants in
microclimate frames. A great deal of interesting data was generated,
and methods of prevention were briefly discussed. The study included
the modeling of emission and deposition fluxes of light organic
acids. As positive pressure airflow is often used to disperse
similar pollution in display cases, my expectation was that a
positive pressure air flow would have the same effect on
microclimate frames.

The study notes that the relative air volume of a microclimate frame
is very small when compared to a showcase, and this will limit the
dispersal effect when passive ventilation is allowed. The study did
not note that a relatively small airflow from an active microclimate
generator can be used to provide a controlled air flow in a
microclimate frame. I believe that an appropriate airflow will
reduce the build up of off-gassed pollutants, especially if the
incoming air flow is filtered.

While it is true that a microclimate generator can provide a clean
and humidity adjusted air flow in appropriate volumes, until now, no
commercially available mechanism existed for supplying an
appropriate flow of air into the frames in an esthetically
acceptable, practical, and reliable method. In response to this
need, we have recently developed a system for injecting a constant
flow of air (at a steady pre-set humidity) into very small
enclosures such as microclimate frames. The system is based on our
proven Mini One constant volume humidity generator with standard
pollution filter and a dedicated air distribution system.

The air distribution system consists of flexible tubing (with
external diameters ranging from about 15 mm to as small as 3 mm),
appropriate connectors, a booster pump, and associated valves and
pressure indicators. Flows of filtered humidity-buffered air into
microclimate frames can easily be adjusted from less than one to
many air changes per day. We believe that a single unit can be used
to provide air for up to 50 frames, at substantial distances from
the microclimate generator.

We expect that this system could be useful where adequate ambient
environmental conditions cannot be maintained and where long-term
display tests the limits of passive microclimate frames to hold
humidity levels. In addition, the system might be an effective means
of purging microclimate frames of off-gassed pollutants where this
is a concern.

The microclimate frames to be used with this active control system
may be created using any of the techniques for passive frames
described in the Propaint project, or in previous postings in this
thread. Air from the Mini One based system is injected through the
back or side of the frame through a very small hole; dispersed air
leaks out through tiny cracks and similar gaps.

We have thoroughly tested the equipment ourselves, and now need to
verify our expectations in a real world application. I am looking
for an institution that is willing to set up a demonstration
installation. We will supply the Mini One and some of the associated
air distribution system. Our partner institution will be expected to
supply microclimate frames, contribute to installing some of the air
distribution system, provide data loggers and / or other testing
apparatus, and of course set up the system in a gallery and monitor
the installation.

If you are interested, or if you know of an institution that might
be willing to help test this system, please contact me off-list.

Jerry Shiner
Keepsafe Microclimate Systems
800-683-4696


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                  Conservation DistList Instance 25:5
                   Distributed: Tuesday, July 5, 2011
                        Message Id: cdl-25-5-002
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