This low temperature soap making technique works best with soap formulas that have no more than 45% hard oils. A 55/45 liquid to hard oils ratio prevents the soap formula from becoming solid at low temperatures.
Making soap using low temperatures prevents the more volatile elements of essential oils and the more delicate top notes of fragrances from burning off during the exothermic heat (gel-stage) of saponification. A gel stage is not needed to complete the saponification process.
Even at very low temperatures, the chemical process of saponification is going to complete itself, just at a slower pace. Heat is a result of friction. The hotter the starting temps of your soap oils and lye solution, the faster the molecules move, creating friction or the ‘gel stage’ that we are accustomed to seeing. Lower temps means slower movement, less friction and heat build up.
Low temperature soap making often results in Non Gelled soap. Since some fragrance oils tend to generate additional heat due to the chemical components in the fragrance itself, you can put your freshly poured Low Temp batch in the refrigerator or freezer. Freezing your soap will not damage or change the composition of your soap. When you take the batch out of the refrigerator or freezer, just let the batch equalize to room temp (let any condensation evaporate) before slicing into bars.
When using a Low Temp method, expect to leave your batch in the mold approximately 12 to 36 hours longer. This is because saponification is slower using low temps. Turn your batch out of the mold when your soap feels firm to the touch, and you feel it will be firm enough to handle. Time will vary with soap oil formula, water amount, and fragrance or essential oils used.
Tutorial of Low Temp Soaping
1. Oils at low temperature. Soap formula oils have been weighed, measured, melted, blended, and then cooled to 78 – 82 degrees.
2. Low Temp pre melted oils, cooled to 82 degrees.
3. Close up of thermometer for oils: Oils are 82 degrees
4. Close up on temp of Lye Solution, Lye Solution is 52 degrees.
5. Adding cold lye solution to cool oils:
6. Stick blending on med to blend lye solution and oils. Sometimes a false trace occurs, but it 'loosens' up with movement even with a spatula. Movement creates friction, which in turn creates small amounts of heat, which in turn loosens the false trace. You can see the thick false trace below.
7. Light trace, continuing to mix lye solution and oils. Fragrance was also added and is being blended in.
8. Fully blended, back to a light - med trace.
9. Pouring off 8 oz of soap mixture and adding a Lab Color Orange Basic to this portion.
10: Ready to add the colored portion back to the pot at medium trace now.
11. Adding colored portion of soap back to the kettle. Swirling in the Pot method.
12. Pour into mold, moving mixture to 'place' swirls as soap streams out of kettle.
13. Soap is still med trace. When done pouring into mold I will set this batch in a cold location to finish ‘setting up’ (saponifying). I will put the batch in the refrigerator or the freezer to prevent any gel stage if I am using fragrance or essential oils that I know generate additional heat.