by waaytoomuchintothis » Thu Sep 12, 2013 11:14 am
Some of the older doors that had a lot of millwork on them, like those arched top glass panels, were made from red oak, with inserts made from other woods, like the maple that Jeremy mentioned. They were sold as paint grade, and saved big money for the builder. These paint grade doors were almost always intended for interior use, or in situations where an exterior door was used in a protected area, like a large porch or mud room. Still others were made from red oak or maple entirely, and they were stain grade, which also meant that the cut of the lumber used to build the door was intended for display. Quarter sawn oak was very popular from 1880-1940, and was actually an essential element of several important styles (Mission, Craftsman, Morris, Stickley, etc). If that is a quarter sawn oak door under that paint, you have something very fine and valuable, not to mention beautiful.
Windowed doors of that era frequently had etched, stained, or cut glass inserts which allowed light to come through, but distorted the view, allowing privacy. The ones that had plate glass usually had curtains made from a sheer material, which was very expensive to make until the early 1900's. In the West, with fewer trees to give significant shade, some houses had Isinglas curtains, which were flexible panels of fish bladder sewn into rollup shades. I only mention it because all of these things produce marks on the door, which you may well want to avoid filling because they are historic.