I have an old (1912) house with pine or fir wood floors
and I think shellac finish over stain. We just removed
some ~20 year old carpet and padding, and the floor doesn't
look too horrible, so we would like to preserve as much
of the original finish as possible.

We are using mineral spirits to remove the gummy pad stains,
but it is not coming off too easily. We have about a 1x4' area
completed in 3 hours, and you can still see some of the spots.
They even seem to look grey or white (dried out) instead of
looking like the surrounding finish.

I tested the finish with water, and in the corners it will
bead up with no white spots, so I do not think there is much
if any wax buildup. The high traffic areas do not bead, but
will soak in and darken the wood.

We have tried plastic scrapers to no avail. Fingernails seem
to do the best job. Acetone removes the finish and lightens the wood.

Eventually we would like to apply a coat of paste wax to add
some protection and shine to the floor.

Any ideas or suggestions?
Jay and Kelli