Laser pointers

Katy Untch <kuntch [at] vmfa__state__va__us> writes

>I've been asked to find out if other museums allow the use of Laser
>pointers in their galleries.  I'd be curious to know what other
>conservators think about the affect of laser pointers on works of
>art.  Is there any better method for a docent to use for pointing?

Richard Newman at the Museum of Fine Arts, Boston has recently
produced a document on laser pointers as a result of various
inquiries about their use in the galleries by our docents and
guards.  This document is intended as a handout for those who want
more information on the types of pointers available and their danger
to people and works of art.  The document also outlines a protocol
for their use in museum galleries. The information we complied was
based on contributions made by various scholarly sources and the web
page: <URL:http://www.princeton.edu/~ehs/laserpointer.html>

    **** Moderator's comments: Unfortunately, as of the time of this
    mailing the above document appears to have access restrictions
    on it.

Here are excerpts from the MFA's Laser Pointer document:

    Lasers pointers manufactured in the United States must have a
    label that states the class of laser in the product. The most
    common laser pointers currently on the market are 'Class IIIA,'
    meaning that they have a moderate power output (1-5 mW).  Of the
    red light pointers, the least expensive and most readily
    available emit 670 nanometer light. Only red light lasers of
    'Class IIIA' or below should be utilized.  If possible, 'Class
    II' red light lasers should be used; these are safer than 'Class
    IIIA' types, but may not have sufficient intensity for use in
    galleries.

    Laser light is highly directional.  If shined directly on the
    retina of the human eye for an extended period of time,
    permanent damage is possible, even from the common red light
    laser pointers.  The FDA has issued a warning on the use of
    laser pointers, and precautions for their use have been
    published in a number of places.  Accidental exposure to the
    beam from a laser pointer, which usually would last a very short
    time (often less a second), will not produce permanent injury to
    the eye.  There are possible temporary effects, including
    flashblindness (a temporary vision impairment, as can occur
    after viewing any bright light), afterimage, and glare.  Red
    light laser pointers pose no other health hazards-for example,
    shining a pointer on skin, even for an extended period of time,
    is not dangerous.  Anyone who uses a pointer in the galleries
    should be informed about safe pointer operation (not pointing
    them at people or on reflective surfaces (such as metals).

    Visible light can produce perceptible changes in some materials.
    For example, sensitive dyes may fade.  Such dyes may occur in
    textiles, watercolor paintings, various types of prints,
    upholstery fabrics, and in some pigments used in easel
    paintings.  Some simple measurements we have made indicate that
    the intensity of light at the spot illuminated by a red light
    laser pointer exceeds the maximum recommended footcandles for
    sensitive works of art.  However, since a laser pointer would
    generally only be held on one specific spot on a work of art for
    a very short period of time, it seems very unlikely that any
    measurable damage (i.e. fading) would occur.  It should also be
    noted that the most common laser pointers emit red light; red
    light has the longest wavelengths and consequently the lowest
    energy of any color of visible light.  A certain number of
    footcandles of red light would be less damaging to a sensitive
    work of art than the same number of footcandles of white light.
    Absorption of the light from the laser by a dark-colored surface
    could potentially produce a local temperature rise; again,
    however, given the length of time on which the pointer is held
    on a specific spot, this is not likely to be cause for concern.
    As a matter of policy, light-sensitive objects should not be
    illuminated by pointers.

Hope this is helpful.  We would be interested in hearing from others
on this topic.

Marie Svoboda
Assistant Conservator
Museum of Fine Arts, Boston

                                  ***
                  Conservation DistList Instance 13:33
                 Distributed: Friday, December 3, 1999
                       Message Id: cdl-13-33-003
                                  ***