Charcoal cloth

Alexandra Zappa <amzappa [at] gmail__com> writes

>I have been looking into the use of activated charcoal cloth to help
>prevent further corrosion of a number of lead coins in an unsealed
>display case with some wooden components but have had trouble
>locating much information that would help to determine the lifetime
>of charcoal cloth.
>
>Does anyone have any experience or information regarding how
>frequently charcoal cloth should be replaced based on the type and
>size of the showcase and pollutant levels? Alternatively, has anyone
>found any reliable indicators that can be placed in a display case
>to help determine when charcoal cloth should be changed?

There is excellent literature in the field on pollution abatement as
well as studies dealing directly with the use of activated carbon to
absorb pollutants (eg the British Museum).

In addition to attending to general pollution absorption in the
showcase, I suggest you consider an option sometimes used in
showcase microclimate control: secondary isolation.  While you can't
bag or wrap the coins on display, you could provide a small
case-within-a-case that could act as a barrier to isolate the coins
from air borne pollutants. Including a small amount of activated
carbon, Corrosion Intercept, or other product in the micro case
should provide protection from any pollutants leaking in.

Use of secondary containment does not preclude the use of pollution
scavenging techniques (there are many) in the surrounding showcase. A
simple lead coupon can be used to indicate when the scavengers have
lost their effectiveness--while not the most sophisticated of
pollution indicators (tarnish on the coupon means that pollutants
are already working throughout the showcase), your most sensitive
artefacts (the coins) would still be isolated in a safe environment
in their inner case.

Jerry Shiner
Keepsafe Microclimate Systems
416 703 4696
+1 800 683 4696


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                  Conservation DistList Instance 25:37
                 Distributed: Sunday, February 12, 2012
                       Message Id: cdl-25-37-002
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