It is essential that the glue be hot and the wood warm, so that the glue may remain as liquid as possible until the surfaces are forced together.

Glue holds best on side grain.

End grain can be made to stick only by sizing with thin glue to stop the pores.

Pieces thus sized and dried can be glued in the ordinary way, but such joints are seldom good.

Surfaces of hard wood that are to be glued should first be scratched with a scratch-plane, Fig.