Foam board

In Conservation DistList Instance: 14:17 Tuesday, September 12,
2000, I wrote:

>I have been asked by our exhibition design department to find a
>rigid, light-weight opaque panel that can be used to form the front
>wall of a large vitrine which will have windows cut in it for
>viewing the objects. ...
>...
>What we need, I think, is a material similar to Gator board (which I
>been told may release formaldehyde).

    **** Moderator's comments: The following is a private response
    from Paul Storch, reproduced here with his permission

    I would argue against the use of Gatorfoam as a case
    construction material since it is not conservation quality due
    to the inclusion of formaldehyde-containing components (See
    CCI-ARS Report #2572: expanded polystyrene core and veneers of
    urea-formaldehyde resin impregnated paper adhered by PVAc glues)
    To use that and have to cover it with Microchamber is an added
    expense and unnecessary in light of other, safer materials that
    are available.  Gatorfoam is intended more as a support for
    graphics or large white-model building rather than as a
    structural support in the application that you outline below.  I
    would imagine that the designer envisions the front wall as
    being removable for access to the case interior, and therefore
    wants it made of lighter board material.

    I have tested several other board materials that are safe for
    conservation purposes that are not much heavier than Gatorfoam,
    are made of recycled materials, and are cost effective:

        1.  Isobord (a Canadian product made from wheat straw.  I
            tested it for both chlorine and VOC's (Oddy Test) and it
            passed both.  I would suggest barrier coating it with
            Camger 1-146 Polyglase Environmental Coating as a
            precaution against acetic acid vapors if they are
            present.

        2.  Bellcomb Wall Systems (Bellcomb Technologies Inc., 2200
            First St. North, Minneapolis, MN  55411):  made
            primarily of recycled paper fibers and kraft paper.  It
            tested negative for chlorine and the pH was 6.7.  The
            polyurethane adhesive and impregnant is formaldehyde
            free.  The material would still require sealing with
            Camger to prevent any problems with acetic acid.

    I think that your idea of hot gluing the Plexiglas to the case
    wall might work, but if you use the Isobord or Bellcomb, you can
    attach rabbets to the inner surface of the wall into which the
    glazing can be slipped, thus eliminating the need to rely on an
    adhesive for long-term strength.  If you do use the hot glue,
    use the clear sticks (EVA) that have been shown to not have any
    harmful VOC's.

    Please let me know if you have any other questions or require
    clarification of the above.  Feel free to post my answer on the
    DistList if you think that it is helpful.

    Paul Storch Objects Conservator

Karen Potje


                                  ***
                  Conservation DistList Instance 14:20
                Distributed: Monday, September 25, 2000
                       Message Id: cdl-14-20-001
                                  ***