![]() It is important that the bronze powder is fully secured to the printed image. Other colors can also be produced by dyeing the platelets with colored dyes. The use of different metals to produce the platelets gives differing tones of bronze powder, plus copper based powders and silver aluminium. Molten metal is processed to produce tiny platelets and the platelets are graded for size, greased and polished. These machines feature a powerful internal vacuum system which draws the surplus bronze from the dusting section of the machine and the powder is filtered and collected to be used again (Figure 5.3).īronze powder is made from brass, zinc alloy and copper platelets. This is done by rotating rollers covered with a soft material. These dusting bands make contact with brushes which are positioned at each end section allowing the dusting bands to be brushed clean as they rotate.Ī final dusting and burnishing is carried out prior to the sheets exiting the machine. The sheets pass over the rubber blanket through the bronzer and the flow of bronze powder onto the tacky image is controlled through a duct similar to a conventional printing press ink duct.Ī series of rotating dusting bands pass over the dusted sheet to remove the surplus bronze and burnish the image area. The bronzing process is illustrated in Figure 5.1 below. The sheet or web is then burnished using rotary burnishing bands of soft material which polishes the image giving the appearance of gold.Ī further pass through the press may then be required to apply a varnish coating to the bronzed area to ensure the correct scuff resistance is met to meet agreed quality standards. A final dust removal is then carried out to ensure that no Image printed using bronze prep residual powder is left on the substrate surface. The excess powder which has not adhered to the image is then vacuumed off the substrate and re-cycled back into the bronze powder reservoir. The ‘ prep’ dries by the oxidation process thus sealing in the bronze powder. Whilst the image is still wet a metallic bronze powder is applied to the surface. ![]() This bronze ‘ prep’ (preparation) is a varnish which contains a colored pigment. The label or sheet of labels is printed (usually by letterpress or litho) with a special adhesive ink known as ‘ prep’. Used in Europe and the USA, today the growth markets for bronzing are in Asia, China, India and Indonesia, where it is also used for security purposes and as an anti-counterfeiting measure.
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