COMPUTER-ASSISTED PRODUCT DEVELOPMENT 787 Figure 4. PERT network-final stages-product through production Figure 5. PERT network R & D functions-critical path analysis for nail lacquers estimates for completion of the network have been established using the criti- cal path method. In the following sections of the paper, specific applications of computer techniques to product formulations, analysis, and color formulations are dis- cussed.

788 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS The computer printout will be listed in the form of a table under the follow- ing headings (3) S = starting event E = ending event D = duration of activity ES = earliest start date LS = latest start date EF = earliest end date LF = latest end date F = maximum float factor **: critical activities RES = resources utilized (PD = product development) The critical path method for a nail lacquer is illustrated in Table I. The float time of an activity is the difference between the earliest and latest start- ing dates. An activity is near critical if the float for that activity is equal to or less than some previously specified float factor. Table I Critical Path Analysis for Nail Lacquer Production • S E D Cost ES LS EF LF F ** RES Base formulation I 2 10 600 12/12/72 12/12/72 12/18/72 12/18/72 0 CR Shade formulation I 3 2 120 12/12/72 12/18/72 12/12/72 12/18/72 8 PD Primaryoeormu]a 2 4 2 19.0 12/19/72 12/19/72 12/19/72 12/19/72 0 CR PD Primary formula 3 4 2 120 12/13/72 12/19/72 12/13/72 12/19/72 8 PD DUM 4 15 0 0 12/20/72 1/12/73 12/20/72 1/12/73 30 D DUM 4 6 0 0 12/20/72 12/29/72 12/20/72 12/29/72 10 D DUM 4 7 0 0 12/20/72 12/20/72 12/9.0/72 12/20/72 0 CR D DUM 4 8 0 0 12/20/72 1/12/73 12/20/72 1/12/73 30 D Paneltest 5 9 10 660 12/20/72 1/12/73 12/28/72 1/18/73 30 TS Safety 6 9 30 1500 12/20/72 12/29/72 1/11/73 1/18/73 10 OS Stability 7 9 40 240 12/20/79. 12/20/72 1/Vt/73 1/18/73 0 CR TS Analysis 8 9 10 600 12/20/72 1/12/73 12/28/72 1/18/73 30 TS Finaloeonnulation 9 10 2 120 1/19/73 1/19/73 1/19/73 1/19/73 0 CR Product 10 11 0 0 1/9.2/73 1/22/73 1/22/73 1/22/73 0 CR MM "Total number ooe activities = 14 total cost -- 4080. COMPUTER lrVOBMLILATIO1NI In any product development laboratory, a given portion of work involves the formulation and reformulation of the product. Often, reformulation is required ,vhen either substitute ingredients or additives are introduced into a product, or ,vhen one mixture of ingredients replaces another mixture.