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Subject: Surface cleaning paper

Surface cleaning paper

From: Niccolo Caldararo <caldararo>
Date: Friday, March 13, 1998
This is reply to the request for more information about my research
on Groomstick and the CCI experiments with different erasure
products. (A 25 words or less answer is that no residue
could definitively observed and no consistent evidence of
degradation products could be established).

I became interested with Groomstick! when so many of my colleagues
starting using it in the mid 1980s.  It arrived at the Western
Regional Art Conservation Laboratory and Pauline Mohr demonstrated
its qualities for me. While I was quite impressed I was also
intrigued by how it worked and by the strange texture and feel it
had.  It seemed to me to be more than sticky, but like DMSO, having
a volatile component.  Shortly after this introduction, a British
conservator wrote to Paper Conservation News reporting the same
sensation in handling Groomstick!, he was sure it must give off some
substance in operation on paper.  I then tried some quick tests and
followed this with a experiment designed to flush out any residue it
might leave on paper.

Using different types of paper I erased pencil marks using
Groomstick!, then heated the treated sheets with untreated controls
and observed the sheets under a microscope.  No residue could be
noted on all sheets, though bits of media could be seen on several
erased sheets. It could not be determined if any degradation had
resulted from the presence of Groomstick residue. Scanning some of
the test sheets under high magnification showed occasional yellowed
areas, but these did not appear on all sheets erased with
Groomstick! Evidence of Groomstick could not be routinely noted
comparing erased and heated or erased and control sheets as compared
with control sheets not erased.  Erased sheets were subjected to
various solvents and heated, still no residue was apparent.
Groomstick was heated on paper and melted into a brown glob as
natural rubber does, leaving the paper stained brown. Heated
Groomstick! does not dry into the sticky mass of the original
Groomstick form. As no residue could be determined from the surface
of the writing papers tested, I tried black matboard to see if any
sheen could be observed.  None was visible after erasure, though
erased areas appeared to reflect light differently.  Perhaps the
antioxidant and a plasticizer are entirely volatile, the fact that
paper treated with Groomstick! does not show any degradation
different than untreated paper after artificial aging supports these
observations.  Other erasers, especially the hard rubber based
products leave residues in the paper fiber structure which can
easily be observed, over time these residues become hard and

The CCI study by Elizabeth Moffatt and Marilyn Laver, "Erasers and
related dry cleaning materials", CCI Analytical Report ARS no 1238,
1981:1-11, found Groomstick! to be processed natural rubber with the
addition of an antioxidant.  Since it displays little deterioration
on exposure to air for more than 6 months, this seems reasonable.
Moffatt and Laver could not detect residue from Groomstick by 30
power light microscope (I used 100x, 200 and 400x) or by accelerated
ageing for sulfur (tarnish test).  The CCI study of erasure
products tested block erasers, powder erasers  and kneaded erasers
with a total of 19 individual products listed for content, and ph,
chloride, residue, and relative amount of tarnish.

                  Conservation DistList Instance 11:77
                  Distributed: Monday, March 16, 1998
                       Message Id: cdl-11-77-004
Received on Friday, 13 March, 1998

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