SPRAY PATTERNS OI: COSMETIC PRESSURE PACKS 459 volume of foam -- volume of liquid X 100 % overrt, n = volume of liquid It depends primarily on the concentration of propellant, and the nature of the aqueous formulations. It is •vorthwhile mentioning that a spray which gives a foam on im- pingement may be obtained when using a standard spray actuator rather than a foam actuator. This method of dispensing is often resorted to when using glass packs as very few foam actuators are suitable for use with 20 min., or thereabouts, valve closures. •.. -•..- •.•. :•--• •.• • .... . ..,/•..•., ... - ,•,, -•.' •-i•-.:...'•t5.-% ' ' • .... -.,.. •-• ?•.i•,•:•?{.,..• ..•,...,.•,.• ß • ...... .• .• .... 5.•.-:a• •x•, a • '",:•: '• ß •-2 ' •'• •' .... 'S.•S...a • .. '•' - :•'•}• .. •2. :. "'•'. " .... c•'• %.. •-•, -.,.,•.- • •.•% • •:.• -.:7- ß ...... • .... " S:..•: "•.': ' a-,•.• gi• ..... •. •. ..•..... :.• •.'• ß ' •. • Figure 6 (A & B).--66% ethyl alcohol, nitrogen at 90 p.s.i.g. Valve "A" break-up spray actuator. For streams the special actuators developed principally for nitrogen packs must be employed and correct discharge is primarily a function of the product itself, once it has been established that the viscosity is not too high for discharge through the selected valve. Propellant pressure merely controls the proportion of the original fill that will ultimately be discharged, i.e., the amount of undischargeable product. Thus once the valve has been

460 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 7 (A & B).--66% ethyl alcohol, nitrogen at 90 p.s.i.g. Valve "B" break-up spray actuator. established, the product discharged will at all times be physically identical with the material originally sealed within the container. Metering valves are necessary in order to achieve drop-by-drop discharge. In order to obtain a good p•:oduct distribution, special actuators (nozzle elongators and so on) are resorted to more often with stream and drop dispensing, than with packs yielding space or surface sprays. REFERENCES (1) Dixon, K., J. Soc. Cosra•TIC C•E•., 10, 220 (1959). (2) Root, M. J., J. Soc. COSMETIC C•E•., 7, 153 (1956). (3) $chimmel Briefs, 233 (August 1954). (4) Herzka, A., Soap, Perfumery, & Cosmetics, 33, 712 (1960) .,Ierosol dge, 5, 30, (1960).