Make Soap with Caustic Soda [NaOH] or Caustic Potash [KOH]
There are at least 3 major processes in make soap several chemicals besides commercial lye (caustic soda [NaOH]) and wood ash lye (potash [K2CO3]) can be used. Of these, commercial lye (caustic soda) is by far the best, fastest, easiest to work with and makes the best soap. However, it maybe necessary use what is ever alkali is available. As to fats, tallow (beef kidney or leaf fat) is the very best animal and olive oil is the best vegetable fat but you can use any fat that is available. Under austere conditions, the best fats should be saved for eating and poorest (opossum fat, carp oil, rancid fats and used cooking grease). Soap made from soft fats (goose fat and fish oil) makes very soft soap but which worked fine for hand washing.
SOAP MAKING PROCESSES
• Warm Process- Reaction occurs at low temperatures from 95 to 120 °F, requires either caustic soda (NaOH) or caustic potash (KOH) and has a reaction time of 30 to 60 minutes with stirring and a cure time of 1 to 2 weeks at room temperature.
• Room Temperature Process- Reaction occurs at 65 to 85 °F, can use sal soda, potash, caustic soda, and caustic potash but the reaction time is very slow at 2 weeks with twice a day stirring as is the curing time at 1 to 2 months (at room temperature).
• Hot Process- Reaction occurs at boiling, uses sal and caustic soda, soda ash, caustic potash or, even, baking soda, the reaction time is variable up to 10 hours with stirring with very slow curing at 1 to 2 months(at room temperature).
• Salt Hardening Soap for Laundry Use- To ordinary cured soap shaved and dissolved in hot water, add about 1 cup salt per pound of lye used in making the soap until the salted soap curdles separates from the liquid (mostly glycerin). Skim off soap curds for reprocessing. Liquid can be further processed to recover the glycerin and salt.
Process Spot Tests
• Room Temperature Process
o Appearance when ready to pour.
1. Mix will turn honey thick, opaque, and slightly grainy.
2. Develops Tailings [lines of soap that float on the top of the mixture surface].
• Hot Process
o Drop Tests: [Drop soap mix on a cool plate and observe]
1. Drop remains clear: good, balanced soap
2. Drop is weakly gray: needs more lye
3. Drop has a weak gray margin: needs a little more lye
4. Drop has a gray skin over the whole drop and the droplet does not stick to the
plate but can be slid around: needs more fat.
o Appearance of Mix:
1. When the mix is thick, ropy and will slide off a wood spoon in a lustrous strand, it is
"green" soap and cab be poured into molds.
o Appearance of Bubbles:
1. Frothy Bubbles indicate that the soap has too much water: continue to stir and
boil down.
2. White bubbles that give a distinctive squeak, indicate that the water content low enough for it to be pour into molds.
Lye Calculation and Over Fatting Soap
• Over fatting is adding more fat than the amount expected to be saponified. This not only makes mild face and hand soap but protects against caustic, over lyed soap.
• To calculate the amount of sodium hydroxide lye for 16 oz. of lard fat to make a finished soap with a 5% excess fat, intersect the Lard row with the 5% column, to find the number 0.132. By multiplying the 16 oz. of fat weight by 0.132, you find that 2.1 oz. of lye needs to be used.
Desired Excess Fat in Finished Soap
• (Using sodium hydroxide lye and lard)
Fat Target Present: 0% 1% 2% 3% 4% 5% 6% 7% 8% 9% 10%
Lye to Fat Multiple: 0.138 0.137 0.136 0.135 0.133 0.132 0.130 0.129 0.127 0.126 0.125
(Using potassium hydroxide lye and lard)
Multiply 16 oz. of fat weight by 0.185 for 2.96 oz. of potassium lye to make 5% over fatted soap. This is due to potassium hydroxide being 1.4x heavier than sodium hydroxide.
• Substituting Alkyl by Weight
• Alkyl Molecular Weight Multiply By
• sodium hydroxide (NaOH) (39.997 g/mol) = 1.0
sodium bicarbonate (NaHCO³) (84.007 g/mol) = 2.1
• sodium carbonate (Na2CO3) (105.9888 g/mol) = 2.65
• potassium hydroxide (KOH) (56.1056 g/mol) = 1.4
• potassium carbonate (K2CO3 (138.205 g/mol) = 3.455
• Water Amount to Add:
• Water weight is 0.38x the weight of fat used.
Preparing Used Grease
• In a survival situation, edible fat will be a scarce and valuable commodity so it likely that you will be making soap with cooking grease that has been repeatedly used for cooking. The used grease can be stored in jars until enough is gathered of it to process. Once it has been cleaned to remove burnt crumbs and, especially, salt, it will make acceptable soap.
• Dirty used cooking grease even if rancid, can be cleaned of impurities by vigorously boiling for at least 5 minutes in an equal amount of water while stirring. Let the mixture cool until the grease solidifies, then carefully remove it from the water, lay it down water side up and scrape off the grease solidifies, then carefully remove it from the water, lay it down water side up and scrape off any impurities still clinging to the surface.
• Very dirty grease, which does not clean with the above process, should be boiled again for at least 10 minutes in an equal amount of water to which baking soda or lye has been added (¼ tsp per 2 lb of grease). Stirred then let cool the grease solidifies, then carefully remove it from the water, lay it down water side up and scrape off any impurities still clinging to the surface.
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