Last updated on October 5th, 2023 at 11:04 pm
Definition of Flock Printing
Flock may be prepared from many synthetic fibres by cutting them accurately into pre-determined lengths using a suitable machine. With cotton and wool fibres, it is usually prepared by grinding and lengths may be as short as 0.3mm (0.013 in). The flock may be dyed or uncolored. A suitable material is chosen to form the base fabric for the flock and the base material, and the flock may be composed of the same or different fibres. The base fabric may be either coated all over on one side with a suitable adhesive resin, or the resin applied locally in a printed design. When printing is used a method which transfers a reasonably thick film gives the best results, e.g. rotary screen printing by the Aljaba or the Stork system or on a smaller scale, flat-screen printing.
The resin adhesive used must be one which adheres firmly to the substrate being printed, but equally so, must be capable of anchoring the flock firmly once it is attached. The resin film must be flexible, have a soft handle and possesses a good resistance to washing.
Methods of Flock Application
The flocking operation may be carried out in at least three different ways, which will now be described.
This method uses special spray guns and is simple to apply. Various sizes spray guns are available and they are used mainly by handicraft workers as well as painters and decorators. When applied by a spray gun, the flocks lie in a completely disordered state and will never produce a clear velvet-like effect.
In this method the flocks are applied merely by shaking, dusting or sprinkling the flock either directly by hand or through a fine sieve. The fabric may be shaken at the same time as the block is being sprinkled. This may be done in the case of small areas of fabric by attaching a wooden rod of hexagonal cross section to the shaft of a small electric motor, and allowing this to come into contact with the reverse side of the printed cloth. As with the previous method, shaking produces a flocked effect on which the individual flocks are attached in a random fashion.
The Electrostatic Method
A lot of development work on this system has been carried out in W. Germany. In principle, a high voltage is generated and connected to two pole-plates, one of which is earthed the other being effectively insulated. Flocks between these pole-plates will Endeavour to close the circuit and spring from one plate to the other in an intense to and fro motion which results in them becoming aligned vertically. When the resin printed fabric is introduced, the flocks are effectively ‘shot’ into it vertically and adhere in the printed areas. Because of the vertical adhesion of the flocks, the desired velvet-like appearance is achieved. A collection device removes excess flock from the treatment area and returns it to the machine for re-use.
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