Steam really works to remove adhesive from hardwood!
I bought myself a $50 wallpaper steamer and went to work on my hardwood floors this past week. It really works! Here are some photos:
Front bedroom before, with glue-down carpet pad of ~70's vintage, judging by the shag carpet on top of it.
I scraped off the cushy part of the pad, and used the steamer on the residue.
And here's the after. Still has some film in a few areas, but it should sand out fine.
Back bedroom before, with some sort of trowelled-on adhesive.
And after (not quite done).
It's about 8 hours of work per 11x11 room, so hasn't gone real fast. But it's not backbreaking work by any means, just slow going and tedious.
The bedroom floors are in decent shape. There's one board with a gouge in it, and a few spots with small divots, but whatever doesn't sand out I'll just leave as "character" marks. Other than the water-damaged hall area, everything I've exposed looks completely refinishable.
The kitchen is another whole ball game, as there's a couple layers of glued-down vinyl to deal with, not just residue, so it requires a lot more elbow grease and upper body strength. :-) But the steamer softens everything up, allowing me to make progress with various and sundry scrapers. And after several rounds I can get down to the bare wood. Here are some progress photos:
This was with a lot of manual scraping with a wonderbar:
And here's after a bit of work with the steamer.