248 SELECTION OF FURNITURE

CONSTRUCTION

No one should purchase a piece of furniture without making a
complete examination of it and acquiring information about it.
The purchaser should look at the back, the bottom, and the inside
of each piece as well as at the front. Drawers should be taken out,
doors opened, drop leaves examined, and surfaces, edges, and
joints studied. Good workmanship is indicated by complete finish
on backs and undersides and by the use of screws, not nails.

Firmness and rigidity under pressure are very important features
of good construction. Firmness depends largely on how the dif-
ferent parts are joined. The legs and the frame (rails) should be
fastened together with glue and also with dowels, screws, steel
clips, corner blocks, or corner metal plates.

Joints in wood are of two types, mortise and tenon, or dowel.
In the first type one piece of wood has a tenon, a projecting block
left by cutting away the wood around it. This is covered with
glue and inserted into the mortise or hole, which has been made
in the other piece of wood. In the dowel joint a wooden peg is
inserted into holes which have been bored in both pieces of wood
to be joined. Double dowels have two pegs. Cylindrical dowels
are best, if grooved spirally and longitudinally to take care of air
bubbles. Too many dowels close together may weaken structure.
The mortise-and-tenon joint is somewhat stronger than the dowel,
but both types are very good. Since a customer cannot see which
type of joint is used she should request that the sales slip should
state what they are, and also name the kind of glue used. Medium-
and high-priced furniture should have phenol-resin glue, which is
very strong and is heat and water resistant. Vegetable glue and
milk-products glue are less desirable and less costly,

Corner blocks should reinforce both types of joints. They are
triangular blocks, cut to fit into the unseen backs of corners, and
glued and screwed to the frame or rails. If nails are used they
should be handled carefully to avoid splitting the wood. Corner
blocks prevent dowels from breaking under heavy pressure. They
are a sign of good construction, but they cannot be used in some
pieces where the legs are inserted directly into the frame of the
chair seat.