David Kern
>Date: 11 Jun 98
>From: Paul Storch <paul.storch@mnhs.org>
>Subject: Shelving
>Nancy J. Cyr <ncyr@che2.che.umn.edu> writes
>>I am writing the specifications for laminated shelving to be used as
>>additional shelving in some 25 year old laminated cabinets. I know
>>exterior grade plywood is supposed to be low in formaldehyde and
>>should be used instead of particle board, but what about adhesives?
>Medite II, manufactured by the Medex Corp., is exterior grade
>particle board that utilizes a phenol-formaldehyde adhesive as the
>binder. It meets conservation specifications. The general
>specification for plywood or oriented strand board (OSB) is:
>exterior grade, American Plywood Association (APA) approved.
>Having said that about the spec for phenol-formaldehyde, which is only
>the glue and/or binder for the layers or particles, there is still the
>issue of the off-gassing of acetic acid and other carbonyl compounds
>from the wood fibers themselves that has to be dealt with. The exposed
>surfaces of the shelving boards still need to be coated or covered to
>prevent these harmful VOC's from adding to the deterioration of metals,
>carbonate-based objects, textiles, paper, and other materials. The
>common misconception with wood-based board materials is that if the
>potential formaldehyde problem is solved, then the materials are inert,
>which is far from the case.
>Pam Hatchfield has done extensive testing and research on this issue and
>has found that Camger Water-borne Urethane coating is the best barrier
>for museum storage applications. Keep in mind that no lacquer type
>resin coating is a 100% barrier to VOC's or moisture, but this product,
>if applied properly in two complete coats according to instructions and
>allowed to cure completely, will provide adequate protection. The other
>alternative is to completely cover the exposed surfaces and edges of the
>boards with a barrier film such as MarvelSeal. A film such as Corrosion
>Intercept, which is not a barrier film but acts as a passive "sink" for
>pollutant molecules, can be used in conjunction with the coated
>shelving.
>Paul S. Storch
>Objects Conservator
>John and Martha Daniels Objects Conservation Laboratory (JMD-OCL)
>B-109.1, Minnesota History Center
>345 Kellogg Blvd West
>St. Paul, MN 55102-1906
>612-297-5774
>Fax: 612-297-2967
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