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This requires a large quantity of agent because the particles are
so finely divided that they have a large surface area. A pound
weight of particles has a surface area of about a quarter of an
acre.
Thin-film coatings Metals can be deposited directly onto
plastic film without the use of binders so achieving 100%
concentration. Three methods are possible. Electroplating with
a primer coating and with small amounts of phosphorous to
provide a grain structure so that magnetic zones can be formed;
evaporation from boiling metal in a high vacuum to reduce the
temperature; and ionic sputtering by bombardment of a metal
cathode by positive ion ...