"Charles Spitzer" wrote in message
...


thanks. what if it is already flat? doesn't poly, or other oil finishes,
self-level pretty well?


Yes, but generally not smooth flat. There will typically be lots of
inconsistencies in the surface. Everything from brush strokes if you use a
brush to differences from the lap if you spray it, or even orange peel.
Dust finds its way in sometimes and the less than perfect surface of the
wood will telegraph in the finish. All of this - or any of this adds up to
a less than flat surface. Depending upon how irregular it is, you will
select a grit to take it down and then progress upwards in grit to be rid of
the sanding marks. With sprayed finishes it's not uncommon to be able to
start no coarser than 1000 grit. Typically, you can go to 1200 or 1500 from
there and then to a fast rub with a rubbing compound for a mirror finish.
In essence, flat is what you want to define flat to be. For some, nothing
less than a mirror finish is flat. That absolutely calls for sanding.
--

-Mike-