Seen on the lamppost.

There are some fancy chemicals available, but for all practical purposes out of reach. Back to basics. It's quite possible the oil in the floor is irremediable, and flooring simply has to be replaced.

Oil spill cleanup seems to be the problem with a former printing company floor that will not clean. Technique now involves applying a combination of odorless paint thinner, laundry soda and Pine Sol in hot water with damp mop. Oily gunk rises to surface in a milky emulsion. Rinse black gunk from mop repeatedly. Dry with paper towel (or other cellulose product). Result is sticky, black floor. Don't know if this is an improvement.

Jennifer Kretschmer, Associate AIA, wrote this study page and link to questions for general structures.

“I.”

Make something beautiful by design.

Anti-matter disposition.