EFFECT OF BASE COMPONENTS ON OXIDATION HAIR DYES 441 0.2-2.0%. The viscosity (of the dye base alone) peaked at 1.0%, dropping off below and above that level. This reflects a typical "salting out" effect of the oleyl alcohol thickener present in this dye base. Vis- cosity of the dye base plus peroxide showed a more complicated pattern of behavior--peaking twice, at 0.5% and 2.0% levels of the sulfite salt. In contrast, drop-movement measurements of this series show a startling minimum at 0.5% sodium sulfite, with values which are only one-twelfth those at higher and lower concentrations of this salt. The distinctive results obtained at this concentration were repeated several times. It should also be noted that the maximum temperature rise rose sharply as concentration of sodium sulfite increased beyond minimal levels. At 0.2-0.5%, the maximum temperature rise was 2øC at 1%, it was 3 øC and at 2%, it was 8 øC. This may have been due simply to the oxidation-reduction reaction with peroxide, or it may have in- volved the dye intermediates as well. This particular series was not repeated without dye. The only effect on shade or color uptake noted for the series was a distinct darkening of shades obtained from aged solutions containing 0.2% sodium sulfite higher levels did not seem to affect color. Replacing Part or All of the Ammonia with Other A mines Several laboratories have noted previous to this paper (7) that extra- ordinarily large temperature rises can occur when dark shades of oxida- tion hair dyes are mixed with peroxide, if a large amount of free amine is also present. To the authors' knowledge, no systematic study of this effect has been published, however. Table XIII shows the results re- placing part or all of the ammonium hydroxide of Base Solution #4 by di- ethanolamine (DEA), triethanolamine (TEA), and monoisopropanol- amine, respectively. This dye base contains no amide, to avoid cloud- ing the issue the thickener used (oleyl alcohol) is "neutral" in two respects: it contains no amino groups and does not contribute to pH changes. The first attempt to achieve the necessary pH levels was solely by use of amines in place of ammonium hydroxide, as previously suggested in the literature (4, 5). This explains the rather extraordinary levels of DEA (18%) and TEA (29%) used in experiments #2 and #3 (Table XIII). The 30 øC temperature rise at 18% DEA should be noted how- ever, as well as the 13 øC rise which resulted from the presence of 29% TEA. There is no question that the effect was much greater for the

442 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 2. Effect of concentration of diethanolamine in oxidation hair dye base on temperature rise on mixing with hydrogen peroxide DEA than for the other two amines checked. The monoisopropanol- amine (at 7%, giving a pH of 10.2) produced a temperature rise of only 3 øC, whereas use of 7.5% DEA produced a 19 øC rise. The DEA effect was then checked in greater detail, and the tempera- ture rise increased approximately linearly with increasing amine con- centration. This relationship can be seen in Fig. 2. The pH was main- tained approximately constant in this latter series (experiments #5-8, Table XIII) by supplementing the DEA with ammonium hydroxide as needed. In general (except for experiment #2 at 18% DEA), the results summarized in Table XIII show no great viscosity effect from varying either the nature of the amine, or its concentration. Drop-movements, on the other hand, at all levels of DEA were excellently low with ammonium hydroxide and TEA, good and with monoisopropanol- amine, poor. It would be impossible to achieve necessary pH levels with reason- able quantities of TEA alone in the oleic acid/oleyl alcohol system used above. Since it produced definite temperature rise at high levels, this