plywood

In the late 18th century, Samuel Bentham discovered that gluing separate thin pieces of wood together to form a composite increased the strength and he registered a patent for the idea in 1797 but as his process used hand-sawn timber it was rather rough and, more important, the final size was limited by the size of the timber that was used to produces the thin planks that were then stuck together. 

However, in the middle of 19th century, Immanuel Nobel, the father of Alfred Nobel, invented a rotary lathe that produced relatively large sheets of thin wood by rotating a trunk or branch while holding a long blade against it that was under tension. That meant that large sheets could be cut or peeled away from relatively thin trunks of trees as long as they were fairly straight and the grain was not too distorted around secondary branches. These thin sheets were then glued together with alternate sheets turned, so that the grain ran across at 90 degrees, and then the sheets were baked.

Industrial production of plywood started in France in the 1860s and was introduced to the USA about 1865. The main products, large timber sheets of various thickness, are used as a building material in construction to line the walls and roof or can be used for shuttering for poured concrete.

Using glue that is resistant to damp and mould, so called marine ply can be used for boat building and in the early 20th century it’s lightness and strength made it ideal for the construction of the frames of early aircraft. 

For furniture, plywood can be sawn and sanded, using normal wood-work tools, although some care has to be taken when using a plane. Particularly when finer or ornately grained veneer is used on the outer faces, plywood can be used as large sheets for cabinets or for the backs of furniture and the sides of drawers but thicker plywood can also be used effectively for worktops and table tops … the edge with alternate light and dark layers can make a very distinctive edge to the worktop.

When heated or steamed plywood can be bent or curved and, if held in that form while it is dried or it is heated, it retains the shape.

In Finland, the properties of plywood for construction and furniture production have been exploited, in part, because although the native birch does not grow to a particularly substantial trunk it has a good regular grain and when used for plywood, is much stronger than softwood ply.

Birch trees in a Finnish wood