Bluing

Brad Epley <bepley [at] neosoft__com> writes

>I am currently researching some of the paints used on objects in our
>collection of Northwest Coast Native Art.  I have come across a
>reference for a laundry bluing, specifically Reckett's Ltd., which
>was apparently distributed by British soldiers in the late
>nineteenth century.  I am looking for information regarding what
>particular pigment the laundry bluing may be (Prussian blue,
>indigo?) and if anyone has tips for its identification with
>transmitted light microscopy or microchemical testing.

There is an article in the Scottish Society for Conservation and
Restoration Journal, 1998 Vol 9/4, pp15-17: Blue in the Pacific by
Gerry Barton and Sabine Weik. According to the Mac & Me handbook, it
is isotropic, refractive index is less than 1.66, it gives a good
red under the Chelsea filter and artificial ultramarine is described
as "deep blue, even in size and colour. Particles usually 1/2 to 3
micrometers. Edges more rounded than natural ultramarine". Natural
ultramarine is described as giving a good red under the Chelsea
filter; "irregular particle size and shape. Some particles may be
partly white. Good blue. Other minerals will be present. Edges
sharp. Fracture often conchoidal. I think also that the topic of Dr
Steve Tarling's (Birkbeck College, University of London)PhD was
synthetic ultramarine.

Margot M Wright
Senior Curator (Conservation)
Marischal Museum, Marischal College,
University of Aberdeen, Broad Street,
Aberdeen AB10 1YS
+4r 1224 274300
Fax: +44 1224 274302

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                  Conservation DistList Instance 13:30
               Distributed: Wednesday, November 17, 1999
                       Message Id: cdl-13-30-008
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