Erasures

Erasures:  errata and further comments.

It has been pointed out that the filter I recommended (Wratten 77A)
is not an infrared filter.   I should have course written Wratten
88A (Wratten 87 and 89B can also be used).   Many apologies.

The electrostatic method (ESDA) mentioned by Bruce Ford is
specifically for the recovery of indented impressions, usually in
the sheet of paper below that actually written on.  Erasures usually
damage the surface of the paper making the toner attach to it in
patches rather than along the writing line. See for example D. M.
Ellen, D. J. Foster and D. J. Morantz, 'The use of electrostatic
imaging in the detection of indented impressions', Forensic Science
International, 1980, 15, 53-60.

Dr. Nigel Seeley
The National Trust
36, Queen Anne's Gate
London, SW1H 9AS
+44 171 447 6521
Fax: +44 171 447 6540

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                  Conservation DistList Instance 9:69
                   Distributed: Friday, April 5, 1996
                        Message Id: cdl-9-69-004
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