i have to re stain a wooden front door that has been baked by the sun
to the point that the stain behind the window in the storm door is a
grayish color with a couple of good sized(4-5 inches long) cracks in
the wood. the part of the door that is shaded by the bottom half of
the storm door is in okay shape. i am planning on sanding the door
with my palm sander but i am unsure about staining or varnishing
after sanding..what is the difference between the two, also, it is an
exterior door(with a storm door)how many coats? should i try
stripping the existing stain vs. sanding? thanks, cj

Unless you sand everything to the same level, you'll have some degree
of color variation. After you do your initial sanding pass, wipe the
door down with mineral spirits. It will color the wood just a little,
giving you an idea of how it will look with finish on it. If you like
the look, go ahead and apply the finish. If not, do more sanding.

I recommend a spar varnish or spar polyurethane. "Spar" means the
finish is appropriate for use on a boat's spar, which bends a lot, and
the finish is flexible. A door that gets direct sun changes size during
the day, so a flexible finish is a good thing. Also check for UV
resistance.

There is no permanent finish for exterior wood. They all have to be
redone regularly. The best advice I've gotten, especially for
west-facing doors, is to use a penetrating oil finish instead of a
film-forming finish. With the oils, you just paint on another coat
every six to twelve months. With film finishes, you have to sand or
strip first.

--
Steve Bell
New Life Home Improvement
Arlington, TX USA