Does oiling both faces really make a difference?

[LBCarpentry]

It's better to regret something you have done than something you haven't.

I had to stop and think about that what the **** are you on about did you just make that up?

 

[Sgian Dubh]

As i read what you've said Richard, is that they way a table top is looked after in terms of cleaning/care etc has a much more influential impact than the rings natural tendency to try to flatten as in a free standing board/plank. This being due to the locking in position of the the parts in a piece of furniture. Am I interpreting correctly then that groth ring orientation then is basically immaterial in the tops construction?

I think you've got it. Permanent set, alternatively called compression set in table tops (for instance) is usually something that develops over quite a long period, sometimes a very long period and caused by moisture cycling. Not every panel experiences moisture cycling to any significant degree, and are therefore such panels are much less affected.

Essentially, the top surface of many panels experience greater wetting on the top surface than they do on the underside, everything from an occasional wipe down with a damp cloth to regular scrubbing with hot water and a stiff bristled brush in the case of food preparation surfaces; the latter example of regular wet scrubbing is probably rare now but not so rare in previous times. Anyway, the result is the wood cells near the top surface of the wood absorb moisture and swell, then dry and shrink again. Over time those cells gradually distort and collapse taking on a permanent set or compression set which can lead to cupping of the whole panel, concave on the top face.

In my experience not every panel develops such cupping, but over the years I've seen it in many panels, mostly table tops, and for the most part they've also been old, e.g., from pre-twentieth century. Slainte.