1135
transferred to 22 Bloomsbury Street.
By 1880 the fi rst commercial platinotype papers were
on sale, with a choice of rough or smooth surface, on
medium or thick paper, at a price of 1/- (one shilling =
12 ‘old’ pence = 5 ‘decimal’ pence) for a sheet 17.75 x
22.75 inches; other sizes could be supplied pro rata at
a unit cost of ca. 4 d/sq.ft (‘old’ pence per square foot).
By 1892, the Company was selling platinotype papers
in nine sizes, pre-cut to match the negative formats then
current, at a unit cost of ca. 8 d/sq.ft, which remained
constant over the next 15 years, and may be compared
with the cost of ca. 3 d/sq.ft for printing-out papers,
and 6 d/sq.ft for the new bromide enlarging papers. For
storage, perfect dryness was of paramount importance,
otherwise the sensitizer became fogged by the action
of moisture; accordingly, the Company supplied the
paper sealed in soldered tins, and recommended storing
it in special tubes containing a desiccant of anhydrous
calcium chloride. Sensitized textiles could also be sup-
plied for 1/- to 1/6 per square foot: nainsook—a very fi ne
muslin; sateen—for d’oyleys, mats, and lampshades;
and rough oatmeal cloth—for screens, antimacassars,
cosies, and mantle-cloths.
Because the process was protected by Willis’s later
patents of 1878 and 1880, prospective users, both ama-
teur and professional, were initially obliged to pay the
Company 5/- for a licence to practise platinum printing.
This requirement was suspended in 1888 when Willis
launched his new cold bath process, described in two
more patents, of 1887, in which the development bath
contained all the platinum salt. It proved short-lived,
however, owing to an uneconomic defect: platinum
metal tended to precipitate from the stored developer.
Willis withdrew this platinum in the bath process in
1892, upon introducing his fi nal, most successful modi-
fi cation, cold development paper, which he protected by
secrecy rather than patent.
In 1885 the Platinotype Company was awarded the
gold medal of the International Inventions Exhibition.
By the 1890s, Willis’s range of papers offered every
combination of texture, weight, more or less contrast,
and black or sepia image—numbering about 20 variet-
ies. These sensitized papers were of two main types: one
could only be developed hot, the other was also suited
to development at room temperature. The image colour
varied slightly, from bluish-black in cold development
(ca. 20 °C), especially using the Company’s propri-
etary D Salts as developer, to brownish-black at high
temperature (ca. 75 °C). Most workers preferred cold
development to avoid scalding their fi ngers. Willis also
devised Sepia platinotype papers, which incorporated
a mercury(II) salt in the sensitizer. These called for
hot development; but to obtain a sepia colour with the
ordinary papers, some workers added mercuric chloride
to their cold development baths.
The company’s platinotype papers were coded by a
single letter to designate hot bath papers, a doubled letter
for cold development papers, and ‘S’ to indicate sepia
papers. Willis later added a parchmentized paper hav-
ing a semi-glossy surface—Japine paper. The surfaces,
weights, and image colours available were as follows:
A, AA Smooth surface, medium weight
B, BB Smooth surface, heavy weight
C, CC Rough surface, very heavy weight,
K, KK, KS Smooth surface, heavy weight, higher
contrast
S Smooth surface, medium weight, sepia colour, hot
bath process
RS Rough surface, very heavy weight, sepia colour,
hot bath process
T, TT, TS Rough surface, heavy weight, higher con-
trast
Y, YY, YS Smooth surface, very heavy weight
Z, ZZ, ZS Slightly rough surface, very heavy weight
Willis purchased the platinum salt, potassium chlo-
roplatinite, from the leading precious-metal refi ners,
Johnson Matthey, whose company records for the sales
of this salt make possible a rough calculation that the
production of platinotype paper was usually in excess
of one million square feet per year.
Other goods marketed by the Platinotype Company
included chemicals, porcelain dishes, printing frames,
and calcium chloride tubes. A director of the company,
Herbert Bowyer Berkeley (1851–1891), was responsible
for one of the most signifi cant improvements to photo-
graphic processing by discovering that developers for
silver emulsions could be stabilized by the inclusion of
sulphite, which enabled the development of negatives
to greater density ranges without fogging. The company
marketed this important innovation in 1882 as the very
fi rst proprietary developer, “Sulpho-pyrogallol.” The
works manager of the company’s factory in Penge,
WH Smith, also collaborated with Willis to produce
a hand-portable ‘Key camera,’ patented on 28 March
1889, which incorporated a novel method of changing
the glass plates.
The chief competitor to Willis’s platinotype was
Pizzighelli’s printing-out platinum paper, invented in
1887, which was manufactured by Hezekiel and Jacoby
in Berlin, Dr Just in Vienna, and Unger and Hoffmann
in Dresden. Such paper was also made in England by
Berger and Company, and by Hardcastle; but the major
photographic companies, Ilford and Kodak, did not
enter the platinum paper market until the early 20th
century. To retail the Platinotype Company’s products
in the United States, the sister-company of Willis and
Clements was founded ca. 1885, with offi ces at 25
North Seventh Street, Philadelphia, later moving to
1624 Chestnut Street. Rival suppliers in the United