I've had people stand and watch in wonder as I slice bread straight!
I've always wondered what's the big deal? I've never found it hard to
do, and the watchers can't figure out how I do it! :) Now, I don't
pretend that my slices are all machine-perfect, but they are largely
straight and mostly even.
Have you ever used a saw on a board? you line up the saw on the mark
where the cut goes, use your eye to make sure it's straight then you
saw, continually watching it for straightness.
Slicing bread is the same, as far as I'm concerned... hold the loaf in
the left hand (I'm a rightie), use the thumb as a guide for the knife
by placing the thumb the "right" distance from the previous cut and let
the side of the blade touch the tip of the thumb, visually line up the
knife so it's parallel to the previous cut (assuming it was straight)
and watch it, correcting for alignment errors as you gently saw away at
the bread.
I've seen bread slicing guides offered in catalogs (wouldn't be surprised
if the King Arthur web store offers one) but never tried using one. I
wouldn't think they'd be particularly convenient...
Good luck!
Fred Smith -- fredex@fcshome.stoneham.ma.us