Metal containers decoration

Although it is possible to modify the planar surface of a metal container by indentation inwards (debossing) or outwards (embossing), the term decoration usually refers to one or other of the printing processes. This may be preceded or followed... 

The vast majority of metal containers built-up from sheet materials are decorated in the flat prior to fabrication. The process most used (offset lithography) was used for printing on metal long before it was adapted for printing paperboard. A process which is basically dry offset lithography is also being increasingly used. 

Metal containers produced by impact extrusion must be decorated as the last stage rather than the first stage. The process normally used is rotary dry offset letterpress. Drawn containers may be decorated either before fabrication (by offset lithography) or after fabrication (by dry offset letterpress). The choice depends on the depth of draw and the amount of distortion which can be tolerated. Deep drawn components are invariably decorated after forming. 

An alternative method, which provides a greater degree of protection than a simple snap-on cap is to apply a screw finish to the container so that it will accept a prethreaded plastic or metal cap. The actual neck finishes applied to metal containers, and hence the caps used, are not identical to those applied to glass. Aluminium caps are usually preferred for compatibility and appearance reasons in that they can be made to match the container itself. Like the container they can be plain or lacquered internally and externally and decorated or embossed/debossed with a logotype. Due to their relatively shallow depth, caps are produced by drawing rather than impact extrusion. 

Although the convenience of plastic bags is perhaps outweighed by their blight on the environment, think of what we would not have if we had none of the polymeric materials invented by chemists and then fabricated in bulk. Think of a world without nylon and the polyesters of fabrics for clothing, upholstery, and decoration. Think of a world with only heavy metal containers for drinks, food, and household fluids. Think... 

Finally, the dendrimer or star may be surface or internally functionalized or decorated with metal-containing motifs. This type of dendrimer is widely investigated with a view to preparing novel catalytic systems in which a dendritic effect results in enhanced or modified catalytic properties with respect to a similar number of mononuclear complexes. As many of these species are strictly organometaUic they do not fall properly within the scope of this volume. 

Hard plating is noted for its excellent hardness, wear resistance, and low coefficient of friction. Decorative plating retains its brilliance because air exposure immediately forms a thin, invisible protective oxide film. The chromium is not appHed directiy to the surface of the base metal but rather over a nickel (see Nickel and nickel alloys) plate, which in turn is laid over a copper (qv) plate. Because the chromium plate is not free of cracks, pores, and similar imperfections, the intermediate nickel layer must provide the basic protection. Indeed, optimum performance is obtained when a controlled but high density (40—80 microcrack intersections per linear millimeter) of microcracks is achieved in the chromium lea ding to reduced local galvanic current density at the imperfections and increased cathode polarization. A duplex nickel layer containing small amounts of sulfur is generally used. In addition to... 

Chromium makes up just 0.012% of the Earth s crust, yet it is an important industrial metal. The main use of chromium is in metal alloys. Stainless steel, for example, contains as much as 20% chromium. Nichrome, a 60 40 alloy of nickel and chromium, is used to make heat-radiating wires in electrical devices such as toasters and hair dryers. Another important application of chromium metal is as a protective and decorative coating for the surface of metal objects, as described in Chapter 19. 

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