Efficacy of Molecular Traps in
MicroChamber Papers
Acids:
It is
interesting to note that our molecular traps are significantly more effective than
an alkaline buffer at removing acids, and unlike buffered-only papers, they
will remove by-products of deterioration such as aldehydes which form acetic
acid. This is important because acetic acid is the primary by-product of
deterioration produced both by paper and by photographic materials. One
of the most dangerous pollutants to paper is acetic acid As the effects of
acetic acid build up in a paper artifact, it accelerates degradation My goal
was to identify materials that would be most effective at absorbing and
retaining acetic acid, and that would be suitable for use in preserving
artifacts. I looked at about 18 different materials, including activated
carbon, clays, calcium carbonate, and several zeolites The activated carbon and one of the zeolites-called
SPZ, (the zeolite Conservation Resources developed for use in Artcare board,
conservation boards, papers and materials) performed significantly better than
the other physical adsorbents based on its adsorption and retention of acetic
acid-which can be assumed to inhibit cellulose deterioration-the SPZ zeolite,
incorporated in Artcare (and) MicroChamber technology (products), is a very
viable material for preventative conservation applications. 1
The results
from our tests using gas chromatography show that if we have equivalent
papers—for example a 65 g/m2
interleaving paper, or a 130 g/m2, .006" thick envelope paper, or a
standard 250 g/m2 archival
file folder paper in both MicroChamber paper and buffered paper, the
MicroChamber papers have 170 times the acid-removal capacity of the buffered
papers. In other words, the buffered paper would have to be replaced 170 times
before you would need to replace the MicroChamber paper.
1.
From an interview with James Druzik, Senior Scientist, the Getty Conservation
Institute, printed in the October 2003 Decor magazine.
By-products of
deterioration:
MicroChamber papers are very effective
at removing pre-acidic by-products of deterioration, such as aldehydes. These
pre-acidic deteriorative by-products pass unaffected through traditional
buffered paper because the deteriorative by-products do not react with the
alkaline reserve in buffered papers. If we assume all of the acetaldehyde (a
precursor to acetic acid) removed as deteriorative by-products by the
MicroChamber paper will become acetic acid, we find the MicroChamber paper can
remove what would become 231 times as much acid as would form if only the
buffered paper were present.
Pollutants:
MicroChamber
products do provide protection against common oxidative and acid gaseous
pollutants such as ozone (O3), oxides of nitrogen (NOx, NO, NO2), sulfur
dioxide (SO2), as well as H2S, CS2, ammonia, formaldehyde, peroxides and a
great many other such molecules which can harm collections. The
traditional alkaline buffers in conservation papers do not react with or remove
these deleterious molecules. Furthermore, such molecules can pass unaffected
through even the thickest buffered boards 2,
where they can contact and damage collections housed within these buffered
boards and papers. If, for example, we look at New York City and at Los
Angeles, the EPA (The U.S. Environmental Protection Agency) gives us the
maximum hourly rate of a variety of pollutants measured in these two cities for
one year. Using these maximum concentrations, we can calculate the maximum
amount of a pollutant such as SO2 in one liter of air. Exposing a 24 x 36
MicroChamber folder to a fresh liter (slightly more volume than a quart
container) of polluted air every hour, we find, at the maximum hourly
concentration level of pollutants measured in New York and Los Angeles, the
MicroChamber folder has the capacity to remove the SO2 in NY city for 8219
years, and in LA for 26,224 years. Obviously if the air exchange is increased
this figure will be lower. For example, if the air flow rate into the folder
was increased to 10 liters per hour, the figures would drop to 1233 years for
NY City and 3933 years in Los Angeles, CA. Of course the MicroChamber product
will also pick up other harmful molecules, in addition to the SO2. Therefore to
the extent these other molecules are present and removed, the maximum quantity
of SO2 which can be removed will be lowered-but these figures do at least
provide a point against which you can form a comparison between the
effectiveness (zero) of buffered products and of MicroChamber products.
The preservation advantage offered by
our new MicroChamber boards and papers, which contain both specialized
proprietary molecular traps and alkaline buffers, is quite striking. While
traditional alkaline buffered conservation papers and boards do provide an
advantage over acidic commercial products, this improvement does not begin to
approach the phenomenal gain in protection offered by MicroChamber products
over traditional alkaline buffered products. Alkaline buffered paper is a
technology of the 1960s. MicroChamber materials give you the advantage of
technology from the 1990s. MicroChamber products offer new opportunities in
preventative conservation, increased life and thus reduced preservation costs
for all collections. See the MicroChamber product verses traditional
buffered-only test results on our website.
2. Guttman, C. M. and
Jewett, K. C. 1993 Protection of Archival Materials from Pollutants: Diffusion
of Sulfur Dioxide through Boxboard, Journal of the American Institute for
Conservation 32:81-91. Also, see MicroChamber test section on our website.