COTTON-tipped applicators, commonly used for applying liquid nitrogen, are difficult to provide with shaped points, and in addition, hold little of the fluid. Polyurethane foam can be used to make a liquid nitrogen applicator which can be shaped to as large or fine a point as may be desired. The porous mesh of the foam will hold relatively large amounts of liquid nitrogen, reducing the number of times the applicator must be dipped into the supply.
Polyurethane foam is a soft foam rubberlike material used in packaging and in upholstering. It is easily obtained from discarded sample boxes or may be purchased in most hardware or upholstery supply stores.
To make the applicator the foam is cut by cutting with scissors. The entire process takes only a few minutes.
When the foam applicator is dipped into the liquid nitrogen it becomes quite firm. Lifting the applicator vertically permits some
Levit F. A Liquid Nitrogen Applicator Made From Polyurethane Foam. Arch Dermatol. 1968;98(2):177. doi:10.1001/archderm.1968.01610140075018