Why is there a progressive reduction in oil for finish/maintenance? Is it necessary?

Question

For oil finishes, such as tung or linseed, it's common to see advice where you apply multiple coats early on, then fewer and fewer coats progressively. For example, a common adage is: "Once a day for a week, once a week for a month, once a month for a year, and once a year for life."

I understand why you would want to do multiple coats early on (as a finish) and a few coats over the long run (for maintenance). But what is the purpose of the intermediate phases, i.e., in the example above the once a week/once a month phases? If it's simply to continue the finish, couldn't you just compact those into the finishing process (e.g., roughly once a day for three weeks), then swap to the maintenance phase?

Answer 1

If it's simply to continue the finish, couldn't you just compact those into the finishing process (e.g., roughly once a day for three weeks), then swap to the maintenance phase?

It's possible this may work for some*, but not in my experience. The main practical issue is that as you build up the oil in the surface wood fibres with the initial coats the wood becomes successively less and less absorbent, and by a certain stage (which will be variable with wood type and minor differences in technique) this can lead to multiple later coats applied closer together more easily building up to a gummy surface. And any amount of soft surface film is to be strenuously avoided when doing an oil finish.

*No two workshops are exactly the same and two people working in Phoenix and Tampa respectively would not have anything close to the same experience during even the first week!

And I wouldn't suggest you go as far as 20 coats anyway. Something that is not clearly stated in almost any guide is that past a certain point you gain nothing with further applications of oil, which is something either implied or directly stated by many old-timers giving advice on finishing ...the type of person most likely to trot out the old adage you quoted :-) You do definitely gain something by applying more than the 2-4 coats that are not uncommon today, but past about six or eight I defy anyone to see any difference whatsoever (on most woods) if they are applying the oil in the correct manner.

Here's why: after the initial buildup within the wood oil finishing is nearly entirely about burnishing of the surface, not "building up the finish" in the sense that most people would understand it (particularly if they're more familiar with varnish or an oil/vanish product like "Danish oil").