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Figure 4
In addition to the factors affecting trace, we wondered whether it was necessary to reach trace in order to prevent separation of soap in the mold. We made up two identical 2-kg batches of our 4-oil soap. They were poured at 44oC ( 111oF) into vertical molds, one at a viscosity of 143 cP and the other at 282 cP. After two days in the mold, they were cut into bars and the alkalinity of the top and bottom bars was measured by titration. In both cases, the top and bottom bars were neutral to phenolphthalein indicator, meaning that they were not excessively alkaline. There was no measurable difference in alkalinity between the top and bottom bars. We took that to mean that there had been no separation in the mold, despite the fact that both batches had been poured well before trace. The viscosity of soap, however, remains an important parameter for the many crafting techniques that soapmakers use to produce their wonders. The temperature of your oil prior to mixing is the most important factor in controlling that viscosity.
of different known viscosity (water, olive oil, castor oil) and come up with an equation to relate “pipet-sec” to cP. But for your brand of pipet, you can simply use pipet-sec as your own private unit of viscosity. Figure 3 shows the viscosity of palm oil soap using units of pipet-sec on the left and cP on the right. Thin trace was observed at 12 min (10 pipet-sec), medium trace at 19 min (15 pipet-sec), and thick trace at 23 min (20 pipet- sec). That is, at a thick trace, it takes 20 seconds to  ll the pipet to the 1 mL mark. Your numbers may differ from ours because the tip of your pipet may be larger or smaller, but if you use the same brand consistently, you should be able to distinguish thin, medium, and thick trace. You can even use the poor soapmaker’s viscometer to determine how close you are to trace before there is any visible effect on the surface of the soap.
We used the more accurate Norcross Shell cup to measure the viscosity of our standard 4-oil soap (39% olive oil, 28% coconut oil, 28% palm oil, 5% castor oil) at temperatures of 40oC (104oF), 50oC (122oF), and 60oC (140oF). In each case, medium trace was observed at about 30 Shell Cup-sec
(500 cP). Figure 4 shows that the warmer the soap was, the more quickly it reached trace. Thus, if you routinely record the temperature of your soap, you can hasten or slow trace in future batches of the same soap by raising or lowering the oil temperature prior to mixing.

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