MACHINE PRINTING

rapidity of production, is totally different in technique from blockprinting. Plate 84 gives an explanatory diagram of a modern three-colour printing machine; each of the engraved pattern rollers (A)receives the requisite amount of colour by contact with the colourroller or furnisher, which revolves in its colour trough or tray.

The surface of the engraved roller after receiving its colour isscraped quite clear, except the sunk or engraved portion, by thesteel colour doctor ; the coloured pattern is then transferred byconsiderable pressure upon the soft fabric as it revolves with thelarge cylinder.

Where the position of the rollers will permit, a lint doctoris placed in contact with the pattern roller after it leaves thecloth, to gather up any lint before the roller touches the furnisheragain.

The number of rollers and the size of the cylinder are neces-sarily determined by the number of colours required to produce thepattern ; they may range from one to twenty. The scale of thedesign is determinedby the width of thefabric and the cir-cumference of thepattern rollers, whichare nominally 1 6 Fig. 45.—Colour Printing,

inches. These

rollers, however, are frequently reduced in course of time to 15inches, owing to the necessity for turning the rollers down whenthey are required for other patterns.

The size of the pattern repeats will therefore be 16", 8", 4", 15",7 \ n ’, 5", 3J", 3", and 2 \”'. The larger the pattern, and the morenumerous the colours, the greater is the cost of production.

Where larger patterns are required, or where the quantity of aspecific design is insufficient to repay the cost of engraving a largenumber of rollers, the printer then has recourse to block printing.

It is perhaps singular that the oldest method of textile printing,which is with wood blocks, should be still in use side by side withthe modern machine with its accuracy of register and rapidity ofProduction. This is largely due to the quality of colour obtainableby the use of the block, especially in large and bold patterns: byquality is meant the infinite variations of tone and hue of the colourwhen it is impressed on the cloth.

The annexed diagram (fig. 45) will doubtless explain the differ-ences in the resulting colour by the two processes.

The block receives the required amount of colour by direct

G 97

Colour

.Colour

.Felt, or wood.

■MetiU strip

Copper roller

wood block