This paper refers to the research of techniques for the measuring evaporation of droplet under laboratory controlled conditions. One aims to select chemical evaporation suppressors for further practical usage. Four chemical compounds mixed with the spray mixture were investigated and the evaporation speeds were compared with that of pure water. Out of the four, only the O.E.D. (particularly indicated for spraying) performed satisfactory results, reducing evaporation rate about thirty times. So its use land wide swath air blast sprayer as well as in aerial spraying may have a good chance to succeed.