Vinegar (5 % acetic acid)
Replaces some or all of the water.
Opens the calculator’s starter recipe, 1000 g of oils, with this additive at the dose it fills in, ready to change.
What it is
Vinegar is acetic acid diluted in water: about 5 % in kitchen vinegar, and at least 4 g in every 100 mL under US rules. Vinegars sold for cleaning differ, from 3.5 % with a surfactant added to 30 % grades.
Dunn, Scientific Soapmaking primary source, FDA primary source, Harris primary source, USDA FoodData Central primary source
How much
- 50 % of the water filled in Classic Bells supplier or guide
The calculator fills in 50 % of the water: 154 g for the 1000 g of oils in its starter recipe.
When and how
- Usually: in the water, before the lye.
- Also used: at light trace.
Classic Bells supplier or guide, Faiola, Milk Soaps primary source
What it does to the recipe
- Every 100 g takes 3.33 g of sodium hydroxide, which the calculator adds to the lye.
- 95 % is water, taken off the recipe’s water.
Dunn, Scientific Soapmaking primary source, FDA primary source, Stoichiometry primary source
Worth knowing
- Caution: This is for 5 % vinegar. Cleaning vinegar is sold at other strengths, some with detergent added, and a stronger one takes more lye. Stoichiometry primary source, Harris primary source
- It may need cutting sooner than usual, at 8–12 hours. Classic Bells supplier or guide
- One book says vinegar lowers the soap’s pH; another source says it does not stay an acid in soap. Here the lye is raised to neutralise it. Faiola, Milk Soaps primary source, Classic Bells supplier or guide
Spoons and drops
- 1 tsp ≈ 5 g
- 1 tbsp ≈ 14.9 g
- 1 cup ≈ 238 g
USDA FoodData Central primary source
INCI name
Acetum
- CAS number
- 90132-02-8
- EC number
- 290-419-7
- In the finished bar
- with NaOH, Sodium Acetate; with KOH, Potassium Acetate
Guides that discuss it
Sources
Kevin M. Dunn, Scientific Soapmaking (Clavicula Press, 2010): "666 g of sodium hydroxide to react with 1000 g of acetic acid" (p. 165); vinegar is about 5 % acetic acid (p. 175); 10 g of NaOH neutralise 16.01 g of citric acid (pp. 354–355); "The most potent preservative was edta ... when added to the lye at a rate of as little as 0.3 ppt" (p. 285).
US FDA, Compliance Policy Guide 525.825: vinegar strength is grams of acetic acid per 100 mL, at least 4 g per 100 mL.
Neutralisation stoichiometry with IUPAC 2013 molar masses: grams of NaOH per gram = protons × 39.997 ÷ molar mass. Disodium EDTA dihydrate (372.24 g/mol) takes 2; sodium bicarbonate (84.007 g/mol) 1; magnesium sulfate heptahydrate (246.47 g/mol) 2; borax decahydrate (381.37 g/mol) 2, to sodium metaborate; malic acid (134.087 g/mol) 2; citric acid (192.124 g/mol) 3. An acidity given in milliequivalents per litre takes that many millimoles of NaOH per litre.
Classic Bells, "Acetic acid (vinegar)": vinegar for up to all of the water, about half usual; "Stir the lye slowly into the vinegar"; the soap may need to be cut "earlier than usual", at 8–12 hours; vinegar does not remain an acid in soap.
Anne-Marie Faiola, Milk Soaps (Storey, 2019): too much sodium lactate makes a "brittle, crumbly bar of soap" (p. 222); apple cider vinegar at trace "will quickly start to thicken the batter", and she writes that it lowers the pH.
P.F. Harris: "Cleaning Vinegar" (lavender), 3.5 % acetic acid with under 2 % decyl glucoside; 30 % vinegar safety data sheet, acetic acid 25–40 %.