What is Flock ?
Flock can be defined as short fibres, which have been cut from monofilament yarn, made from polyester, polyamide or viscose. In electrostatic flocking, millions of these short-cut fibres are fired in an electromagnetic field into a substrate coated with adhesive. The electrical charge causes the fibre to embed itself more or less vertically into the adhesive and thus provide a uniform textile-like surface.
Depending on the area of application and choice of adhesive, the flocked surface can be highly durable and very resistant to abrasion.
Flock fibres are available in various lengths and thicknesses, which are classified both in mm (for the length) and the so-called decitex (dtex) value (for the diameter). Simply put, one can say that the longer and thinner the fibre, the softer the surface; the shorter and thicker the fibre, the more brush-like. The choice of the flock length and thickness determines the primary optical and tactile effects.
Areas of Flocking
There are two distinct areas of flocking and we differentiate between all-over and partial flocking.
In the so called all-over flocking, the substrate surface is completely covered with adhesive and using automatic flocking units, a uniform flock surface is achieved. This is typically used for manufacturing high-quality and durable upholstery fabrics.
Partial flocking can be done using a masking process, but this is usually costly and difficult and therefore is only economical for one-off items. For larger quantities, the process of choice is screenprinting, which offers the advantage that it can be used both for flat substrates and three-dimensional parts, as the adhesive can be selectively printed, thus allowing unique designs to be created.
There are several different adhesive systems for processing flock. These range from solvent-based and water-based, to single and two-component adhesives. The selection of an adhesive depends on the type of substrate to be flocked and what effects are required to be achieved.
The systems for applying flock range from simple to advanced and automated systems. There are simple manual flocking units, which are suitable for small and medium size runs. For advanced use, there are modules which can be integrated into fully automated systems. These latter systems enable even long runs to be produced economically and reasonably priced.
The mesh fineness of the screenprinting fabric presents limitations in the design, when partial flocking is to be carried out. The coarse mesh which must be used restricts the fineness of the design. Furthermore, the length and thickness of the fibres is ultimately decisive for the contour sharpness, and thus for the design selection.
Fine half-tones and very thin lines are almost impossible to achieve, and with small size fonts, the result leaves a lot to be desired. Nevertheless, using flock as a surface finishing method does open up a wide field for creativity, in which many unique effects can be achieved.
In recent years, flocking on paper, cardboard and packaging surfaces, etc. has grown considerably. For example, book jackets, covers, greeting, invitation and gift cards can be printed on a large scale and ultimately enhanced by flocking.
We have found that in many cases, the issue is not simply a question of whether to flock or to print, but to find creative ideas using a combination of both technologies. Thus, a printed substrate can be significantly enhanced by additional flocking. Once more, we are finding renewed interest and demand for high quality wallpaper, which has been made even more attractive by the application of flock.
When we take a surface which has already been flocked, it can be additionally finished by screenprinting or embossing. Also, flocking on three-dimensional parts is on the increase. Take for example, the glove box in a car or the inside of a spectacle case: both have been flocked. More and more, we are finding that glass and porcelain are being screenprinted and flocked. Their flocked surfaces can even be made dishwasher-safe, thanks to the development of a special adhesive. Gift boxes made of wood or metal can be screenprinted with adhesives and then flocked.
In summary, flocking is a process that can be used both in one-off as well as in industrial production. Its application is universal, as we have seen in everyday objects and unique effects can be achieved, presenting constant challenges to the creativity of both producers and screenprinters.