For over 20 years, we used Deft Danish Oil mixed with 20% polyurethane varnish. To choose this product and mix, we tested a dozen or more oil finishes (some with toxic solvents and some without) to find the finish that would resist water spotting the best and achieve a satin look and feel. Deft Oil is no longer made. We had to test again.
Oil finishes are subject to "water-spotting"--that is the appearance of a shadowy mark where water sits for a time. Some are notoriously bad about it.
To find the finish most resistant to water spotting, we applied three coats of the various finishes to sample blocks of wood.
After 3-4 weeks curing, we placed drops of water into a marked grid on the samples.
We dried some of the drops individually on a timed schedule, and let some dry completely.
Originally, we found that Rubio Monocoat (with its accellerater) was the best of 10 candidates. NOTE: WE HAVE SUBSEQUENTLY FOUND THAT RUBIO FAILED ITS PROMISE. ONE: IT GAVE SOME OF US A RASH. TWO: IT DID NOT ALWAYS PROVIDE ADEQUATE PROTECTION FROM WATER SPOTTING.
The company claims Rubio is a one coat finish (monocoat). For the results we are after, it is not. The company did not respond to our reports on the rash.
We now use Old Masters Tung Oil Varnish, adding 25% polyurethane varnish. We wear masks and run our VOC scrubber (scroll down to see.)