X-radiography and watermarks

The following appeared on Exlibris and is reposted here with permission.

    Date: 11 Jan 94
    Sender: Rare Books and Special Collections Forum
        <EXLIBRIS [at] RUTVM1__BITNET>
    From: Daniel J. Slive <dslive [at] brownvm__bitnet>
    Subject: X-radiography and watermarks

    Readers of this list may be interested in the following excerpt from
    the notes section of the December 1993 Print Quarterly, p. 402-403:

    X-Radiography and Rembrandt.  The Rijksmuseum now occupies a leading
    role in the examination of watermarks in paper, and has already
    reached some important new conclusions concerning Rembrandt's
    etchings.  The spur to progress has been given by recent technical
    developments that allow watermarks to be X-radiographed much faster
    than before.  Developed by the dentist and collector H.M.M. van
    Hugten in association with the print dealer Theo Laurentius, the new
    technology can produce a photographic negative of a watermark in
    around two and a half minutes by using "soft X-rays": an emission of
    as little as 7kV at 15mA through the paper onto a film, exposed for
    about 150 seconds, produces a clear and publishable image.
    Previously, the best results were through beta-radiography, which
    requires an exposure of several hours.

    [Two paragraphs on Rembrandt research results (editions, states,
    etc) deleted.]

    The fruits of this research will become more precisely defined as
    more prints are examined. An interim progress report appeared in the
    Bulletin van het Rijksmuseum, XL,1993, pp. 353-384 (with an English
    summary on pp. 417-420), and further, more detailed results are
    promised soon.

                                  ***
                  Conservation DistList Instance 7:50
                Distributed: Wednesday, January 12, 1994
                        Message Id: cdl-7-50-017
                                  ***