I’ve heard it suggested that linseed oil (raw or boiled) should be applied to wood floors before applying oil-based polyurethane. Various reasons are given: seal the wood, establish a better bond, or add color.
Doing this is risky, however. Raw linseed oil can take months to dry. Boiled linseed oil can take a week or longer deep in the large pores of oak.
If you apply polyurethane before the linseed oil is thoroughly dry, the linseed oil and polyurethane will mix right on the wood and create an oil/varnish blend, which will never get hard. It would be like brushing or spraying a wet coat of Danish Oil and not wiping off the excess.
The finish will be soft and it will scratch easily, when what you surely want on a floor is a very hard film of polyurethane. The finish could also be sticky, which would not be functional at all on a floor.
