646 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table VI Results of Factorial Design of Experiments for Samples Refrigerated at 4.5øG Batch No. __ Variable Final Con- Vege- Final Process sistency Protein- table Stirrer Water Temp After Glycol Lime Oil Speed NH4OH Temp (øC) 4 Days ø I -- -- q- - + -- 40 1 34 2 2 -- + -- -- + + 4O 2 34 2 3 -- -- + + - + 40 2 34 2 4 -- + -- + - -- 4O 2 34 2 5 + -- + -- - + 40 1 34 1 6 + + .... :•0 1 34 I 7 + - - + + + 4O 2 34 1 8 + + + + + + 40 2 34 2 9 + - 0 + 0 0 40 2 34 2 10 q- - -- q- + -- 4O 1 34 2 • When compared with a control (typical production sample), the judgment is subjectively made and classified as 0 (fair), 1 (good), or 2 (excellent). for a period of up to one week, allowed to come to room temperature, and then examined. The results of these examinations at the end of 4 days are sum- marized in Table VI and include only the results of the factorial experi- ments for those batch samples that were refrigerated at 4.5øC because none of the samples held at 34øC developed an acceptable consistency and/or structure. Apparently then, cooling of the samples is necessary for the rapid crystallization of the acid soap from solution. The most notable feature of these results is that consistency was obtained at 4.5øC with little or no effect on color. The tests showed, that at the level of variation studied, the structure- forming mehanism was hardly affected. Based on the results of the factorial experiment, no obstacle to the implementation of a continuous •nanufacturing process up to the refrigeration cycle was found.

MANUFACTURING PROCESS FOR COSMETIC CREAM 647 PILOT STUDY OF tHE CONTINUOUS MANUFACTURE OF THE CREAM AND EVALUATION OF PERTINENT EQUIPMENT This phase of the overall study was concerned with gathering data from pilot studies in the mixing and cooling of the cream and utilizing the information gained to draw up a proposal for the final design of a continuous system. The design goal was a process ,that would produce a uniform cream that was pearlescent white, that had a firm consistency, and good stability and application properties. An experimental test loop was set up. The purpose of the test loop was twofold. First, the loop was used to demonstrate the continuous in-line manufacture of the cream. In addition, experiments conducted provided information for scaling up the process. Mixing and cooling are the two most critical operations in the process. Figure 2 shows a schematic of the test loop. •'!•: PJ• Pr•T• • aJ• •o Figure 2. Equipment test loop for continuous in-line mixing and cooling PI. Pressure indicator TI. Temperature indicator VA. Volt-amp meter The aqueous phase ingredients and oil phase ingredients were heated to 60øC. Temperatures throughout the process were controlled to main- tain 60øC up to the point of the in-line mixer. This temperature was selected to be high enough to insure that all ingredients were liquefied, but not so high that potential large heat-exchanger capacity was needed. The ammonium hydroxide was added to the hot aqueous phase just prior to emulsification. The metering pumps (Fig. 3) were previously calibrated with the respective product phases to achieve the proper ratio of oil/water and a final product flow in the test loop of 200 lb/hr. The two phases were then pumped into a common line to an in-line (Fig. 4) xnixer. The viscosity of the product leaving the mixer was sufficiently high to warrant a low-capacity booster pump (Fig. 5) (200 lb/hr) to move the product through the scraped-wall heat exchanger (Fig. 6) and into a holding vessel (Fig. 7).