[ponch37300]

When do you use a U notch over a square notch trowel?

 

[oh'mike]

I've only seen U-notch trowels in larger sizes--all mine are square notch except for an old Saltillo trowel---3/4" deep if I remember right.

 

[JazMan]

I agree with Mike. I think the curved tops help keep the ridges from drooping. I doubt it makes much difference except in the person who thought of the idea's bank account. Like this one.
http://www.custombuildingproducts.c...notch-trowels/premium-notch-trowel-large.aspx

Jaz