The present invention relates to a method for minimizing the buildup of set gypsum on a tool used to apply a calcium sulfate hemihydrate-containing composition to a surface as well as to a method for cleaning a tool having set gypsum deposited thereon. The method for cleaning a tool having set gypsum deposited thereon comprises the steps of (a) contacting the tool with a cleaning solution having a pH of less than about 7, said cleaning solution which comprises a non-calcium phosphate, water, and, optionally, a pH modifier; (b) optionally agitating the solution; (c) removing the tool from the cleaning solution; and (d) rinsing the tool with water. The method for minimizing the buildup of set gypsum on a tool further comprises step (e) using the tool to apply a calcium sulfate hemihydrate-containing composition. An additional step (f), flushing the tool with water, may also be employed. Optionally, steps (a) through (e) or (a) through (f) may be repeated during the application of the calcium sulfate hemihydrate-containing composition. Examples of non-calcium phosphates which may be used in the cleaning solution are sodium, potassium, or ammonium salts such as tetrasodium pyrophosphate, tetrapotassium pyrophosphate and sodium tripolyphosphate.