Patent GB-314359-A (GB)
Title: Improvements in or relating to the production of coloured designs and the application thereof to the manufacture of woven fabrics
IPC: D03C3/20
Filed: 1928-03-23
Abstract: 314,359. Twyman, F., Smith, C. F., and Hilger, Ltd., A. March 23. 1928. Addition to 227,072. Optical - projection apparatus.-In producing coloured designs for woven fabrics, a specimen pattern is first woven in contrasting colours; then a number of photographic images are made in which certain colour constituent parts of the pattern are suppressed, transparencies obtained from these photographic images being then optically projected into proper mesh upon a screen there being means for selection and variation of the colour of each of the images projected; the colours in which the pattern is to be woven are then determined by recording the approved projected colours by means of a colorimeter or coloured cards illuminated by daylight or the equivalent. A suitable apparatus for the photographing and projecting is described in the parent Specification. In the case of a three-colour pattern the weaving may be done in threads of three colours, e.g. red, green, and blue, so selected that they can be photographed through filters each suppressing the other two colours; positives of the three negatives are then prepared (or the negatives reversed chemically) and mounted in the projection lantern for projection of images in mesh. Filters and means for altering the brightness are employed for varying the colour and intensity of the component images. In the case of designs with more than three colours the design may be divided into a number of areas each woven in three or four colours only and photographed separately in the manner already described. A pattern consisting of five differently coloured components may be projected by weaving a sample coloured, as in the striped pattern of Fig. 1, red (R) green (G), blue (B), black (b), and white (R); a negative with four images is then prepared by the use respectively of a red, green, blue, and another green filter or no filter at all and a positive, Fig. 3, printed therefrom so as to obtain a positive having transparencies of the red and white, green and white, blue and white, and the white components respectively of the pattern of Fig. 1. A second negative, which is to be cemented face to face with the positive to form a transparency for projection, is shown in Fig. 4; this is obtained by photographing the white component three times with the other green filter referred to above with or without a filter (these three images being superposed on the portions of the positive, Fig. 3, corresponding to white in the images containing the red and white, green and white, blue and white), and photographing simultaneously with or without a filter the red, green, blue, and white components. Fig. 6, shows the transparency with the images lettered correspondingly with Fig. 1. An alternative second negative may be prepared by photographing the pattern through blue, red, and red filters respectively and obtaining a fourth image of all the components except the black. In printing the positives, particularly where the positive is to be afterwards combined with a negative, it is arranged that the light for making the positive follows the same path as the light used in projection. A procedure for dealing with a six-colour pattern is described in detail, the colour additional to those referred to above being orange-yellow. Suppression of unwanted colours may be obtained by illuminating the pattern with a illuminant, e.g. a mercury vapour lamp, whose spectrum consists of one or more predetermined monochromatic radiations; the colours in the pattern may be produced by dyes each transmitting light corresponding to the illuminant spectrum. In order to suppress surface reflection from the fibres the pattern may be immersed in a transparent liquid of the same refractive index as the fibres. In order to produce an auxiliary effect such as a " sheen " a positive image of the high lights may be added; alternatively an oblique beam of light may be projected on to the screen. In the case of designs in two colours in which the two parts of the design are exactly similar a single piece is woven in black and white and one photograph is first taken and then the piece moved so that the white and black portions interchange positions and a second photograph taken, the lens photographs being afterwards projected. When the two designs are not similar two pieces may be woven in black and white, the patterns being relatively reversed in the two and the pieces photographed separately; or the second weaving may be avoided by making a negative containing two photographs of the pattern images, making a positive from one only of these, and scraping away or bleaching out the negative image from which the positive has been made, and binding or cementing the positive and negative face to face.