Two different woodworkers asked if it’s OK to put polyurethane over 1) Danish Oil on cherry end table or 2) teak oil over small teak garden bench?
Michael Dresdner: Yes to both. Oil-based polyurethane is fully compatible with other oil- based finishes. However, if they want to use water-based polyurethane, the answer is no.
Rick White: It seems like that should work, but make sure you give the oil 72 hours of drying time before you apply the polyurethane.
Ian Kirby: It all depends on what’s in the can labeled ‘polyurethane.’ In the beginning of its life, polyurethane came as a two-can product. It had to be mixed in certain proportions and you couldn’t mess with the mix. The chemistry involved is now well beyond that stage and today’s formulations are tolerant. My guess is that it would be fine, but read the label on the can; it should give some direction. You might prepare the surface of the object by sanding and/or thoroughly wiping it with thinners.