Aerial spray deposits were measured on collection surfaces using two methods: spectrophotometry for Day‐Glo®, a fluorescent dye tracer; and gas‐liquid chromatography (GLC) for triethyl phosphate (TEP), a chemical tracer. The spray mix consisted of glycerol, water, Atlox®3409F and the two tracers. It was sprayed on May 4, 1988 at 5 L/ha over an 8‐ha flat area of the Sault Ste. Marie airport, using a Cessna 188 aircraft equipped with rotary atomizers. Balsam fir‐shaped aluminum branch tips, natural fir needles and glass plates were used to collect deposits.