The following is excerpted from Vol. IV of “The Woodworker, The Charles H. Hayward Years,” which covers the shop & furniture.
As a general classification some six general types of doors have been evolved over the years, though the variations on each are almost unlimited. Only a few can be illustrated here, but the reader should find the range useful when he comes to design or make up a piece of furniture.
The purpose of a door is clear and obvious enough, yet the variety of ways in which it has been made over the years is amazing. Consider, for instance, how far removed the delicate-traceried door in Fig. 2 is from the single slab oak door in Fig. 1, virile and spirited though the latter is. Of course, the two belong not only to different ages, but also to different techniques of construction. Obviously, too, the usage the two would have to face would be entirely different, the Gothic specimen standing up to everyday use, whereas the eighteenth-century door belongs to a cabinet intended for a drawing room, used only by genteel people.
At the outset it is interesting to consider the reasons for changes in construction, apart from the variations in form largely dictated by fashion. A single slab of wood is the simplest form but carries with it certain disadvantages, perhaps the chief of which is its liability to shrink. It might also cast, though both of these potential faults would be minimised by the use of quarter-cut timber. Possibly a more serious drawback is the limitation imposed by the widths in which timber is available. A wide door would have necessitated jointing and possibly using cross-battens at the back. A last undesirable feature is the single grain direction. Oak is a tough wood, but it does cleave easily, and such a door could easily break.
It was no doubt a combination of these drawbacks that brought about the framed system of construction. The frame itself provided strength across width as well as height, the panel being more or less a filling. Being free to move in its grooves, there was no liability to split in the event of shrinkage, and the over-all width of the door could be increased—in fact it only needed centre muntins for the width to be increased ad lib.
The introduction of veneering made it desirable to have flush surfaces, and so the clamped and flush panelled door was used, not always with success owing to its liability to split due to resistance to shrinkage. Finally today we have veneered flush doors of multi-ply, lamin-board, or chipboard, in which many faults have been eliminated (though even here there are certain snags).