Wood used to be made out of trees.  Stunner, I know and you are wondering what I think wood is made of now if not trees. I know wood is ultimately derived from trees but so much of what we call wood is pretty far removed from the tree. For instance, where in a 24″ diameter tree would you cut a 4′ X 8′ slab of 3/4″ plywood from? That would be pretty hard to do, right? So you see my meaning that while the wood that makes the plywood comes from trees, the plywood, itself, does not directly come from a tree.

Traditional studded doorWay back in the old days, if you needed a broad flat piece of material, say to make a door from, you were fairly limited in your choices.  Metal was heavy and expensive. Stone was heavy period. So what about wood? wood was pretty good but it came in pieces that were too small to cover any meaningful doorway. So the best thing to do was to cut some pieces that were long enough to go from top to bottom of the opening, and then cut some that were long enough to go from side to side. Nail all these pieces together with the long ones vertically and the shorter ones horizontally and you could make a door any size you needed it. Since nailing the two layers together meant the nails were going to show at least on one side, the heads were made large and ornate. They were nailed in from the outside so the points protruded from the door on the inside. Well, that was a little bit dangerous and it was also not very secure. The nails could work loose and the door would become weak and wobbly. The points would also be kinda hard to deal with if you brushed against the inside of the door. So the pointy ends of the nails were hammered over flat against the inside of the door. This was called “clinching” and it held the two layers of wood more firmly together as it prevented the nail from backing out and it made for a smoother interior of the door.

The problem was, nails were expensive to buy or make. They were, each one, made by hand. When you needed a nail, the first thing you did was to go find one that had been used for something else and pull it out. You just didn’t NOT re-use nails. But what about a nail that had been clinched either for a door or something else? The nail was pretty much useless as it could not be re-used ans was therefore considered “dead”. Therefore, we have “dead as a doornail”.