I've also seen masonite used in interior work that has worked out okay as you say concerning the insides of TDs. I'm sure it will still work well in that application. But if I had my druthers, I'd go with plywood mostly because of weight savings and the thin plywoods are pretty flexible.
Where'd that stuff come from anyway?
Masonite was developed in Laurel, Mississippi in 1920 by William H Mason, an expert on wood derivatives and an associate of Thomas Eddison. At this time timber mills in the USA were burning huge quantities of waste wood, wood thought to contain too much bark to be of any use. Mason knew that the timber waste contained the same fibres that give wood its tensile strength so it followed that in some way this timber waste could be utilised for other purposes. In the early 1920's, Mason began to experiment ways of utilising this timber waste. He heated a closed vessel loaded with waste chips. When the temperature and pressure reached a high point he opened a valve which caused the chips to literally explode and to form a feather light fibre.
After extensive trials and research, Mason developed a process, quite by accident, to condition this fibre into a high density material. The accident occurred when Mason went to lunch forgetting to release an experimental 19th century press. The press had a leaky valve, resulting in heat and pressure being applied for an unusually long period of time. When he returned Mason found that the fibre, which had originally been intended as an insulation board, had been pressed into a dense, thin, tough sheet. The sheet did not crumble, split, splinter nor crack. The word was then introduced to the versatility and practicality of hardboard, which became known world wide as MasoniteTM. The breakthrough had occurred and in 1924 Mason established the worlds first hardboard plant, The Mason Fibre Company. A year later The Mason Fibre Company changed its name to Masonite Corporation and in 1935 Masonite shares were listed on the New York Stock Exchange. In 1988 Masonite Corporation was taken over by International Paper Inc.
In 1940, William H Mason, the founder of Masonite, passed away and over the period following the Second World War the company undertook extensive research and development to create a whole new family of products including, grained wall panels, moulded door facings and a raft of different coated products.