Glue pattern (from ripped out rug) on hardwood

Q: I started ripping out an old shag rug from a hardwood floor and found that it had been glued down, much to my dismay and surprise. What is left is a red, chalky substance about ¼ of an inch thick, with a weird line design that makes it look like a truck floor.

The work was done by an old company in Philadelphia in 1972, and the glue/adhesive has dried into a chalky substance that is almost impossible to remove by hand (e.g., scraping). Do you have any suggestions on how to remove it?

A: Probably the simplest means to deal with this is to hire a professional sanding company. Preferably someone who uses a vacuum system with their equipment to capture the dust. As long as the floors have enough wear surface to tolerate a full sanding, this is the way to go.