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Subject: Vellum cloth

Vellum cloth

From: Barbara Hamann <hamannb>
Date: Tuesday, March 27, 2001
Emily O'Reilly <emily_gilbert [at] hotmail__com> writes

>I'm working on some city plans carried out in ink, wash and pencil
>on impregnated linen rolls, some as large as 3 metres. I've come
>across a stamp on the back of the linen "By Her Majesty's Royal
>letters Patent, The Vellum Cloth, Dowse Patent". I'm interested to
>know if anyone else has had experience of working on this material
>or could shed any light on it's manufacture. The plans have been
>heavily used suffering from tears and losses, many with old repairs
>of varying quality including pressure sensitive tape.

According to the Official Catalogue of the Great Exhibition of 1851,
held in London, an inventor and manufacturer named Jeremiah Smith
showed "Dowse's patent tracing and writing cloth for Engineers,
Surveyors, Architects and others."  The patent granted in 1846 to
"Charles Dowse, of Camden Town, in the County of Middlesex,
Gentleman," is generally considered to be the beginning of the
modern article, although his patent specification does not mention
tracing, and refers only to the "manufacture of fabrics applicable
as substitutes for paper."

The fabrication method described in Dowse's GB Pat. No. 11,329
includes the following steps:  hardsizing with resin and alum to
reduce wettability of the fabric, surface sizing with starch to seal
down fibers and to add stiffness, drying and glazing between rollers
or plates to produce a smooth writing surface.

Specifications of the patents which followed Dowse's offered recipes
for improving the translucency of the material or for making it
waterproof. Although more expensive and more difficult to work on
than tracing paper, tracing cloth was used when durable or permanent
copies were needed. Polyester drafting films began to supersede
tracing cloth in the 1950's.

Although this material is commonly referred to as tracing linen or
drafting linen, documentary sources record that the tracing cloth
made in England, at least, was made from cotton.  The written
evidence was not contradicted by the fiber identifications carried
out on 96 drawings, spanning 100 years, during my research on
tracing cloth at the Institute of Archaeology, University of London.

The Institute of Archaeology may be contacted for a copy of my BSc
Dissertation, "The Examination and Treatment of Railway Engineering
Drawings on Tracing Cloth," submitted in 1989 to the Department of
Archaeological Conservation and Materials Science.

Barbara Hamann
Objects Conservator, Head of Conservation
Carnegie Museum of Natural History
O'Neil Research Center
5800 Baum Boulevard
Pittsburgh, PA   15206
412-665-2607
Fax: 412-665-2751


                                  ***
                  Conservation DistList Instance 14:51
                  Distributed: Tuesday, April 3, 2001
                       Message Id: cdl-14-51-006
                                  ***
Received on Tuesday, 27 March, 2001

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