Plastering Trowel
Professional plasterers use only top quality trowel like Marshalltown ranging from 11" to 20" depending on what stage the plasterer is at.
For the application of the finish plaster (laying on) a plasterer may use a 13" or 14" trowel. Once he/she has finnished applying the coat they most probably use a 16" or 18" trowel to flatten out any lines, fill hollows or misses...