Content Handbook F

Outline of method

53.1 Wetting time of a standard tape

A weighted length of cotton tape is dropped into a tall cylinder containing an aqueous solution of a wetting agent. The time required for the thread connecting the weight and the tape to relax is recorded as the sinking time. Concentrations of wetters requiring a sinking time of 15 sec are compared. The test may be used on formulated pesticides but it does not necessarily apply to cationic wetters.

53.2 Wetting of leaf surfaces

A freshly picked leaf is immersed in a solution of wetting agent under standardized conditions and a visual examination of the area wetted is made. The minimum concentration of wetting agent, which will produce complete wetting of a cabbage leaf, is normally that concentration which will give a sinking time of 15 sec by the tape test (MT 53.1)

53.3 Wetting of wettable powders

A weighed amount of the powder is dropped on water in a beaker from a specified height. The time for complete wetting is determined.

Scope

53.3 Wetting of wettable powders

The method describes a procedure for the determination of the time of complete wetting of wettable powders.