Sanded??? I never sanded the floor. That's what's so great about shellac.
It don't need no stinkin sandin
You just paint it on. Let it dry between layers about a half hour or so and give it another coat. Let dry and repeat, I usually do 3 coats. If it ever gets scratched just give it another coat. The scratches disappear because the new shellac melts the old and blends in. I use the Zinser shellac already mixed in the can that you can get at Lowes or Home depot. Some people use flakes and mix up thier own with denatured alcholol, but the Zinser works fine for me.