Patent GB-693356-A (GB)
Title: Method of dyeing and a device for use in making up dye recipes
IPC: G01J3/46
Filed: 1950-02-03
Abstract: A specified material is dyed in the colour of a given sample, using not more than three given dyes, by the following successive steps: (1) the values of the XYZ stimuli of the eye (as defined by the International Commission for Illumination) are determined for the sample; (2) three charts as defined below are selected having as nearly as possible the same XYZ values; (3) the amounts of the dyes to be used are found from the common intersection point <PICT:0693356/IV (c)/1> <PICT:0693356/IV (c)/2> <PICT:0693356/IV (c)/3> <PICT:0693356/IV (c)/4> of the curves on the charts; (4) the material is dyed with these amounts of the given dyes under the conditions specified on the charts.  The charts are provided in sets of three, one each for the X, Y and Z stimuli, each chart giving the possible combinations of the three given dyes which will produce, under the specified dyeing conditions, the desired value of the appropriate stimulus.  Each chart is on translucent material so that when superposed on one another the concentrations of the three dyes that will give simultaneously the desired values of the three XYZ stimuli can be read off.  Typical charts are shown in Figs. 1-3 and superposed in Fig. 4.  In practice, three dyes are chosen for each particular fibre, having sufficient substantivity therefor and capable of covering the whole range of desired shades when mixed in suitable proportions.  The dyeing conditions are found experimentally and sufficient information regarding temperature and duration of dyeing, presence or absence of dyeing assistants, &c. is included on the charts to enable the results to be reproducible.  A number of different dyeings (e.g. 200) is carried out with different proportions of the three dyes and the XYZ values for each piece of dyed material are found with a photo-electric colorimeter.  A preliminary set of graphs is then drawn (of which Fig. 10 is an example) showing the variation of X stimulus with dye concentration and the results replotted with different co-ordinates to give a chart as in Fig. 1.  Similar sets of graphs are drawn for the Y and Z stimuli and re-plotted to give Figs. 2 and 3.  Sufficient of the sets (as Figs. 1-3) are made so that the XYZ stimuli of given samples can be matched as closely as is desired in practice.  A separate series is required for each type of dye and each different fibre, those shown being for acid dyes on wool.  When using the charts, the set is chosen having XYZ values nearest to those found experimentally from the sample, the three charts of the set are superposed (as in Fig. 4) and the necessary concentrations of the three dyestuffs read off from the point of intersection of the curves.  Dyeing is then carried out according to the directions given on the charts.  If the match is not sufficiently close, <PICT:0693356/IV (c)/5> e.g. when using a different material from that specified, it may be improved by a method of successive approximations.  If it is known that there is no chemical or physical interaction between the dyestuffs, as is the case for acid and chrome dyes on wool, the procedure for making the charts can be simplified by carrying out a few dyeings only and calculating the remainder of the range of XYZ values.  In other cases also this can be done and the results tested to see if further experimental dyeings are necessary.  Two examples are given of the matching of grey and green shades respectively, using on wool the acid dyes Java Naphthol Red 6B, Java Yellow T.A. and Java Blue V. The values for the first example are those shown in Figs. 1-4.  The method is applicable to the matching of colours on textiles, paper, synthetic resins and any other solid or liquid coloured material.