EFFECT OF BASE COMPONENTS ON OXIDATION HAIR DYES amine should therefore be eliminated from further consideration. The monoisopropanolamine gave excellent pH control and a reasonable tem- perature rise on the other hand, but poor control of drop-movement in the particular base system studied. These results confirm unpublished reports (7) from other laboratories. The presence of more than 2.5% DEA (the lowest level tested) in a dye base solution can result from the use of DEA as an alkalizing agent in place of ammonia (4, 5), or from faulty amide manufacturing, resulting in the presence of a substantial amount of free amine in the amide thickener. Sample #6 (5.0% free DEA) was repeated without dye. A temperature rise of 2øC was obtained, instead of the 6 øC rise obtained with dye present. It is important to distinguish between actual "free amine" and total titratable amine. Most amide manufacturers measure total titratable amine by simply dissolving the amide in alcohol and titrating directly with HC1. In the case of diethanolamides, this is often reported "as diethanolamine." This is not free amine, however, which should be measured by first extracting the amide with a solvent such as ether- xylol, and then titrating the remaining water-soluble fraction with HC1. Many manufacturers do not differentiate between these two values the difference can be enormous. For example, Base Solution #2 adds 15% of a hydroxyethyl stearyl amide to the dye bases reported in Table XI. The temperature rises recorded for this series of tests were gen- erally 1 øC. Yet, this amide contains 23% diethanolamine if measured as "total titratable amine" if this were "free" amine, able to react with the dye intermediates and peroxide, about 3.5% DEA would be available in the final dye base. Such a high level of free DEA would produce temperature rises of approximately 5-6 øC (Fig. 2). When measured by the ether-xylol extraction method, however, this particular amide is found to contain only 0.78% free DEA. The low temperature rise observed in connection with its use in this and other hair dye bases confirms this low level. An anomaly concerning dye bases containing amounts of free amine is that the pH drops drastically after they are mixed with peroxide. The pH can drop from the pH range 9.5-10 to the pH range 7-8 two or three hours after mixing with the peroxide. This does not occur with systems which do not show large temperature rises, and may be further indication of a reaction forming an amine oxide of some sort in the presence of the dye intermediates. Distinctive color effects were noticed as the level of amine was raised in this series both the DEA and TEA interfered with dye uptake

444 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS when present at high levels. At 2.5% free DEA, there was apparently no interference (in comparison to the ammonium hydroxide standard) at 5% DEA, some effect is noted, and this interference increases approxi- mately in proportion as the level of DEA is raised thereafter. It was not felt that the temperature rise noted (in the dye base mass plus peroxide) was a significant factor in dyeings made from these mixtures, because the dye was applied to the hair on a cold plate and left to stand 30 minutes at room temperature thereafter. SUMMARY A method of evaluating hair dyes for their tendency to drip from the head during application has been developed into a semiquantitative test. The "drop-movement test" involves measurement of the distance that a drop of dye solution will move down a glass plate under standardized conditions. This was only one of a number of tests performed on several stan- dardized dye base solutions into which ten different classes of hair dye additives were incorporated. The effects of these additives on viscos- ity, temperature rise on admixture with peroxide, pH, clarity of the solutions, and on the color yield on human hair were also determined, both on fresh solutions and on solutions which had been aged 1000 hours at 2 øC and at 48 øC. Very little direct relationship has been found between the viscosity of a hair dye base and its drop-movement. However, the per cent in- crease in viscosity, on dilution with peroxide before actual application to the head, does seem to be related. The greater such increase, the less the drop-movement. The best compound in each class tested can be determined by consulting the tables. Excessive temperature increases, resulting when the peroxide is added to oxidation dye solutions, are attributed to the presence of free amine, especially diethanolamine. Unusual temperature increases are also associated with the use of more than 1% sodium sulfite. ACKNOWLEDGMENT The authors thank Lowenstein Dyes and Cosmetics, Inc., and Van Dyk and Company for their support of the research reported in this paper, and for permission to publish the results. (Received October l l, 1967)