Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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Dutch gold ( Dutch leaf, Dutch metal )

The generic name for a blocking foil that has found considerable use as a substitute for gold leaf since the latter years of the 19th century. It was introduced in Germany and its use, in sheet form, expanded rapidly, followed by a similar foil in roll form. Although often referred to as "bronze leaf," bronze being an alloy of copper and tin, it is actually composed of brass, which is an alloy of copper and zinc. As the amount of copper is increased, the color of the leaf deepens. Unlike gold leaf, Dutch gold discolors, tarnishing more rapidly in polluted environments. When blocked on leather, the leaf or foil turns green very quickly; and even when blocked on cloth or paper, it will eventually discolor. Discoloration is due to the action of gases in the atmosphere, such as hydrogen sulfide (H 2 S), plus heat and light. Great differences exist in the rate of tarnishing among the various brass foils, however; flat foil for some reason discolors less rapidly than the rolled Dutch gold. This may be due to the high melting-point waxes used on the flat foil but not on the rolled, which coat the metallic particles after they are deposited on the material in the blocking process. This coating apparently acts as a (partial) seal against the deteriorative effect of the atmosphere. Because of the chemical action of the plasticizers in pyroxylin fabrics, the deterioration of the foil is more rapid on these fabrics than on starch filled fabrics. (233 , 236 , 264 , 356 )

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