Inventor of Orr’s Zinc White
John Bryson Orr had devoted himself to the search for a satisfactory white pigment and a sound practical method of producing it commercially.
Nearing ninety years of age, he said:
“Little did I think when I began experimenting, about 1860-1861, with a view to producing a new white pigment that I should see that pigment grow to such importance as to create a new industry with its present day output of over a quarter million tons annually.”
For it was at that time that he carried out experiments on mixed zinc and barium pigment and seven years later produced the pigment in bulk. In 1872 he set up a factory in Glasgow for the manufacture of Lithopone. While the Frenchman G.F. de Douhet must be considered the pioneer of the lithopone industry, it was Orr who perfected the technique and developed a viable method of production. In 1874 he patented the process for making Orr’s Zinc White.1
Put simply, Lithopone is a chemical combination of zinc sulphide and barium sulphate. However, the method of preparing the pigment is a complicated one, involving both precipitation and calcination processes. It was the latter vital stage that Orr discovered and that led to his success.
In 1880, shortly after his factory had been burnt down he formed the Silicate Paint Co. in Charlton, on the outskirts of London. Here he manufactured lithopone (sold under the name of Charlton White) and the first washable distemper, known as Duresco. To many people Duresco was at one time synonymous with washable distemper, although others became well known. The achievement of Orr’s deserves to rank equal with his pioneering of lithopone, and certainly it is in washable water paint that lithopone was to become most familiar in the home and elsewhere. Indeed it is no exaggeration to say that the washable distempers (or oil emulsion water paints, as they were called) were made possible by lithopone as no other white pigment was really satisfactory as an ingredient in such paints.
In order to produce his Orr’s Zinc White large scale industrial processes were required.
Zinc ore was roasted to zinc oxide and then dissolved in sulphuric acid and the solution purified. Barytes, the insoluble mineral sulphate of barium, was roasted with coal to make the water soluble sulphide and extracted to a clear solution. The two solutions were mixed and the resulting white precipitate of zinc sulphide and barium sulphate roasted. The “calcine” from this operation was dumped into water, dried in an oven and eventually packed as the finished product.
The workers of Widnes, in Cheshire were accustomed to handling this kind of chemical operation and on a massive scale, for the alkali industry based on the Leblanc process was then well established. Furthermore, here was an area which was ideally suited for the chemical industry – close to Cheshire salt and Lancashire coal, with abundant water supplies and the cheapest gas in England. The River Mersey, with its associated waterways and the rapidly developing railways promised excellent transport facilities and at rates attractive to a venture in its infancy. The newly constructed Garston Docks, for example, extracted no dues from Widnes merchants, who received favoured treatment and the Port of Liverpool offered direct access to all the world.
The growth of the Vine Works was typical of the wider development of the town. The Kenyon brothers set up a small zinc smelter and flux works on the site of what had once been a farmhouse that had once been noteworthy for its vine. They called their site the Vine Chemical Works. They seem to have concentrated on zinc purification for in 1886 they took out a number of patents. At the same time they also produced some zinc oxide which they ground into oil and sold in paste form.
J.B. Orr realising the advantages of Widnes as a centre for large scale production of his new pigment arranged for Thomas Kenyon to deal with the manufacturing, while he looked after the commercial development in London. The partnership seems to have begun in about 1896, but presumably did not work out because on the 21st July 1898 Orr’s Zinc White Ltd. was incorporated as a limited company.
For every ton of zinc sulphide an equal amount of barytes ore was required and so the company developed barytes mines, first at the Wrentall Mine, Minsterley, in Shropshire, then at the Gasswater Mine at Old Cumnock, in East Ayrshire, and later at the Cow Green Mine, South Durham, near Middleton-in-Teesdale. In this way continuity of supplies was assured.
The paint and colour manufacturing activities of Orr’s Zinc White Ltd., were carried on until 1923 when they ceased because the sales of the pigment lithopone had grown to such an extent that it then seemed desirable to concentrate entirely on this aspect. In order to develop Orr’s Zinc White for purposes other than paint, in 1902 Mr James Ferguson of Glasgow had been given the sole selling agency in the United Kingdom for the Linoleum, India Rubber, Cable and Asbestos trades, and thanks very largely to his efforts the new pigment soon became as well established in those industries as in paint.
In 1948 a book was published to celebrate the Jubilee Year of Orr’s Zinc White Ltd. and most of the photographs illustrating this post have been taken from this.2 By this stage it was a subsidiary of the Imperial Smelting Corporation, and some idea of the facilities in the Widnes plant can be seen below.
Its Importance in Paint
Until the gradual introduction of titanium dioxide in the 1930s lithopone was one of the most effective white pigments available. It covered better than either white lead or zinc oxide and was more flexible than the latter. It was inert in the presence of sulphur gases which tended to discolour white lead paint. However, it did have the drawback of blackening when exposed to the sun and of chalking; hence it was not suitable for exterior work. Also when mixed with white lead or colours containing a copper or lead base, it would blacken, due to the formation of sulphide of lead. This was also liable to happen when a drier containing lead salts was used in the oil paint.3
By the late 1940s lithopone was still the sole white pigment specified by British Standard 1053 for water paint, and an example of the established position of water paint at that time is that the 1937 Factory Act, which prescribed 14-monthly whitewashing for factory premises allowed this period to be extended to three years when an oil emulsion water paint based on lithopone was used.
Lithopone was used extensively in top quality interior paints, in undercoats, flat oil paints and water-paints. By the time that the book was published the following illustration had acknowledged the predominance of the Walpamur brand.
Illustration by courtesy of the Walpamur Company
A very small proportion of lithopone was contained in some later emulsion paints, but it has ceased to be of any importance in the paint industry.
1 Other synonyms include Griffith’s White, Griffith’s Patent Zinc White and Oleum White.
2 Orr’s Zinc White 1898-1948. The Imperial Smelting Corporation Limited. I am most grateful to my friend Keith Edwards for kindly giving this to me.
3 Clifford Dyer Holley. The Lead and Zinc Pigments. Chapman & Hall Ltd. 1909.
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