Re: European patents AND Sury
These are selected citations from GB21958 (you need to digit GB191321958 to find it in the European patents website):No, The process with the name "Color" process is only 1924, it is on my web site, it is easy to read this. The other patents is for the 3 color layers...
"According to the invention a smooth, non-porous support is coated with a colloid containing a hard neutral powder giving a matt surface and sensitized by an alkaline bichromate.
After exposure of the sensitized surface and on development by washing with water the image appears with a matt surface on a smooth background. Th image is strengthened by the deposition on its surface of coloured powders or the like.
According to the invention, also, in order that the development of the image may be followed easily, there may be added to the colloid a pigment which is unaffected by the development but capable of being discharged by a separate treatment."
"The colloid can be gelatine, gum arabic, albumen or a mixture of these substances while the hard and neutral body may be, for instance, glass, sand, or preferably pumice stone, in a finely divided state."
"...there may be added a to the colloid a pigment which is unaffected by the development but may be discharged by the use of a suitable solvent, in a separate treatment. For this purpose there may be employed, for instance, red iodide of mercury, which is solvent in hyposulphite of soda, or prussian blue, which is solvent in neutral oxlate of potassium."
As I have written in a previous message, this method has been proposed with some variations in two following patents (DK19986 in 1915, and CH79504 in 1918). This refinement process ended with the 1924 one (DE405494 and FR580888 in 1924, GB216860 in 1925 and US1571103 in 1926 are the same), where the pigment is ultramarine blue (the "silicate d'aluminium et de sodium et du pentasulfure de sodium").