116 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Because of their film-forming property, the water-soluble resins have been satisfactorily employed in cosmetic formulations. The use of water-soluble resins for protective films has been investigated by several workers. Sperandio and co-workers have prepared an ointment base (1) and a film-forming base (2, 3) with polyvinyl alcohol as the water-soluble plastic. Preparations containing water-soluble resins as skin protectants in film-forming bases were reported in Part I (4) of this series. It was the purpose of this investigation to develop a spray-on bandage with water-soluble resins as the main ingredient and water as the solvent. It is probable that such a product would be better in some respects than the conventional type of spray-on bandages which use organic solvent systems. EXPERIMENTAL The starting point for the development of a spray-on bandage was the formulation of the aerosol concentrate. The major ingredient in the concentrate is the resinous film-forming agent. Several resins were investigated with different plasticizers. The basic formula for the concentrate was as follows: Resins Plasticizers Solvent system Benzoic acid 0.05% Sodium nitrate 0.05 Antifoam 0.1 Nonionic surfactant 0.2 Distilled water With water as the solvent in the concentrate the need for a preservative against mold growth and an inhibitor of corrosion of the metal con- tainer were required. A surface active agent to prevent gelling of the resins and a defoaming agent were also added to all formulations. The concentrate preparations were evaluated for two qualities: The stability of the preparation and the properties of the film formed. The stability tests included viscosity measurements, color, odor, emul- sion creaming, and mold growth. The period of observation lasted 9-10 months. The film properties were evaluated by studying the drying time of the film, the tackiness of the film, the film strength, the resistance of the film to water, and the ease with which the film could be moved. To determine the film properties the concentrate was ap-

AQUEOUS TOPICAL ADHESIVES 117 plied directly on either the back of the hand or on Petri dishes. Despite the subjective nature of the tests, sufficient differences were noted to allow for differentiation of the preparations. In the following discussion of the preparations, the procedure and results are considered in reference to individual resins. Polyvinyl Alcohols The film-forming properties and preparation of aqueous solutions of po!yvinyl alcohols are discussed in detail in technical bulletins and in Part I (4). From the experimental data obtained from the prepara- tion of thirty polyvinyl alcohol concentrates the following was observed: 1. Polyvinyl alcohol rapidly combines with polyethylene glycol to form a gel. 2. Glycerin and sorbitol delay the drying time. 3. Propylene glycol increases the film strength. 4. Triethanolamine markedly increases the viscosity of the con- centrate. 5. Formaldehyde solution USP was the best piasticizer. It has no effect on viscosity, shortens the drying time of the film, improves film strength, and prolongs adhering time. Optimum concen- tration of formaldehyde as a plasticizer for polyvinyl alcohol was 1.6-3.2% (v/v) of the resin concentration. As no free formaldehyde could be detected in the formulations, it was considered to be bound with the polyvinyl alcohol. However, despite the low concentration used and the absence of free formaldehyde, it is realized that the material has potential sensitizing properties and should be carefully tested. Polyvinyl Acetate Unlike polyvinyl alcohol, polyvinyl acetate is not water soluble. Commercial products, such as Gelva ©* aqueous emulsions, are available which form clear continuous films at room temperature. Gelva emul- sions containing 54.5•o of solids were readily diluted with water but were not stable for extended periods of time. * Gelva, a product of Shawinigan Resins Corporation, Springfield, Mass.