Crossbanding was initially a veneered border of cross-grained wood, its purpose being to give strength to the edges of doors, panels, etc., to prevent damage from the occasional bump.
If long-grain veneer were used in crossbanding, it would splinter and chip away from any knocks, and this is why long-grain crossbanding is hardly ever seen.
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The earliest clocks were costly items, made for wealthy clients, principally served by London clockmakers, and rich timbers were used such as walnut and olive-wood.
Cheaper versions were made from about 1690 by provincial clockmakers and for these oak was used, being a far less costly timber, though occasionally pine was used at a lesser cost still.
These earliest oak cases were simple by intent, partly because London styles (which they copied in simplified form) were themselves still simple, but partly because there was little point in offering a clock in cheaper materials if the sheer extravagance of styling made it into a costly clock anyway.
Fruitwood and solid walnut were sometimes used as alternatives to oak at about the same price, but these woods were very prone to worm, were not too popular, and have far less often survived. An early eight-day longcase in oak, made about 1730 by Stephen Blackburn of Oakham, this one an arched dial clock with imposing caddy top, much in the style of a London walnut clock of the period. The earliest longcase clocks (let's say about the year 1700) were made in eight-day form, but also, as country versions, in thirty-hour form, the latter being about half the price of the eight-day.
This trim was usually in walnut or fruitwood from about 1730, generally switching to the instantly popular mahogany, once its import made adequate supplies available from about 1760.
Plain cases in oak alone continued to be made, but increasingly by about 1760 or 1770, they carried some amount of trim in various forms but most often in the form of crossbanding.
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