Lactic acid (88 %)
A harder bar that unmoulds sooner.
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
Lactic acid is sold as a solution in water. This grade is 87.5–88.5 % lactic acid by weight, a liquid about a fifth heavier than water.
Galactic primary source
How much
- 0.5–1 % of the oils (as pure acid) filled in Classic Bells supplier or guide
The calculator fills in 0.5 % of the oils (as pure acid): 5.7 g for the 1000 g of oils in its starter recipe.
When and how
- Usually: into the oils.
- Also used: in the water, before the lye.
- Dissolve it in about twice its weight of the recipe’s water, then blend that into the oils.
Classic Bells supplier or guide
What it does to the recipe
- Every 100 g takes 39.07 g of sodium hydroxide, which the calculator adds to the lye.
- 12 % is water, taken off the recipe’s water.
Classic Bells supplier or guide, Galactic primary source, Stoichiometry primary source
Spoons and drops
- 1 tsp ≈ 5.91 g
- 1 tbsp ≈ 17.7 g
- 1 cup ≈ 284 g
- 1 drop ≈ 31 mg (29–33 mg): droppers differ
Galactic primary source, Österreichisches Arzneibuch primary source, Aroma-Zone supplier or guide
INCI name
Lactic Acid
- CAS number
- 50-21-5
- EC number
- 200-018-0
- As weighed
- Lactic Acid 88 %, Aqua 12 %
- In the finished bar
- with NaOH, Sodium Lactate; with KOH, Potassium Lactate
Guides that discuss it
Sources
Classic Bells, "Lactic acid": "5 to 10 g lactic acid per 1000 g fats (0.5% to 1%)", as pure acid; dissolve it in about twice its weight of water and blend into the oils; "10 g lactic acid neutralizes 4.44 g NaOH".
Galactic, Galacid Excel 88 (lactic acid 88 %), specification: total acidity 87.5–88.5 % w/w; density 1.19–1.21 g/mL at 20 °C.
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.
Österreichisches Arzneibuch (ÖAB), drop table for the Ph. Eur. standard dropper at 20 °C (2024 draft, BASG): refined olive oil 22 mg a drop, sunflower and castor oil 24 mg, lactic acid 29 mg, glycerol 42–43 mg.
Aroma-Zone technical sheets, bottle dropper: CO₂ rosemary extract "1ml = 0.98g = 30 gouttes"; natural vitamin E 32 drops per mL; lactic acid about 36 drops per mL.