reinforced to support the size of your piece. If you see
repeatedly your piece has lost its stretch, started to bow, or
changed shape it could be an indication the framer did not
do a good job of bracing the stretcher bars with proper
fortification. You may want to speak with your framer about
replacing them or consider getting the opinion of a second
Frames customarily have something called a rabbit.
This is an interior grooved portion of the frame. The rabbit
can be as tiny as a 1/8 of an inch, to as deep as _ an inch
with the large frames. If your rabbit is too big or too small
for your artwork it can cause very obvious visual
disturbances.  To help compensate for this, framers will
stretch the canvas to where more or less of the "white" is
used to maximize the amount of image you are seeing
without showing white past the rabbit. When framing paper
artwork the white showing should be equal on all sides
except for the lower portion where the signature is showing.
Next take a look at your canvas for over
stapling. If you get your artwork back from stretching and
you see more than three or four staples per inch along the
sides, this is not a good sign. When you next have the piece
re-stretched the edging will be so torn up you won't be able
to have it done. Should you find yourself with a team of
staples running down your artwork ask the framer gently as
to whether he or she thinks once you remove these staples
the canvas will then be strong enough to re-stretch.  If
they're wise they'll get the message. If they're not wise
you may want to look for a different framer.
Don't forget to look at the back of the painting and
make sure the backing paper is a thick protective
paper. This should be drum tight and have very little give
to the touch. If your art is on canvas make sure the framer
puts air holes into the paper allowing the canvas to breath