Mark-It Blue spray solution colorant. Use to indicate where a chemical spray has been applied. Ideal for use with herbicides, fertilizers, and insecticides. Simply add to the spray tank when it is approximately half full. Eliminates skips and overlapping spray. Washes off without staining, non-toxic, compatible with water soluble solutions, and dissipates with sunlight. Size: 8 Oz. Color: Blue Concentrate or Ready To Use: Concentrate Mix Ratio: 1 Oz. Colorant/1 Gal. Spray