The Big Book of Homemade Hair Care

A shampoo is five systems working together: a primary surfactant for cleaning, a secondary surfactant to soften it, cationic conditioning agents, pH and rheology modifiers, and a broad-spectrum preservative.

The book treats a modern shampoo as an engineered system rather than a recipe, and names five ingredient classes.

Primary surfactants — anionic surfactants such as Sodium Laureth Sulfate (SLES) or the milder Sodium Cocoyl Isethionate (SCI) — do the cleaning. Their molecules surround oil and grease so it can be suspended in water and rinsed away. Secondary or co-surfactants such as Cocamidopropyl Betaine (CAPB) or Decyl Glucoside are added to modify the primary: they improve foam quality and stability, reduce irritation potential and can add viscosity.

Conditioning and stabilizing agents — cationic polymers such as Polyquaternium-10, proteins and silicones — deposit on the hair shaft after cleansing, neutralize static charge, smooth the cuticle and improve manageability. In solid formats an emulsifier like BTMS is essential to bind the oil and water phases.

pH and rheology modifiers set the rest. A shampoo should be slightly acidic, pH 4.5–5.5, to match hair's natural state and help close the cuticle; citric or lactic acid adjusts it. Xanthan gum or a salt such as sodium chloride controls flow and thickness.

Finally, preservation is non-negotiable. Anything containing water supports microbial growth, so a broad-spectrum system — a phenoxyethanol-based blend, or potassium sorbate with sodium benzoate — is required for safety and shelf life.

Source: The Big Book of Homemade Hair Care — The Shampoo Matrix: Beyond Basic Cleansing · Open the article

Divide the active percentage you want by the active percentage of your raw material, then multiply by 100. For 5% active CAPB from a 40% solution: (5 / 40) × 100 = 12.5 g.

Surfactants are almost never sold at 100% purity. A bottle of Cocamidopropyl Betaine is typically a 30–40% active solution in water, and a formula that asks for '5% CAPB' usually means 5% active matter, not 5% of the bottle.

The book gives the calculation directly: if a recipe calls for 5% active CAPB and your raw material is a 40% active solution, you weigh (5 / 40) × 100 = 12.5 g of that solution per 100 g of product.

This matters twice over. Weigh the bottle percentage instead of the active percentage and your shampoo will be roughly a third as strong as intended — it will not lather, will not clean, and will feel thin because the extra water thins the whole system. The water that came with the surfactant also has to be subtracted from the water phase, or the batch will overrun its yield.

Source: The Big Book of Homemade Hair Care — The Shampoo Matrix: Beyond Basic Cleansing · Open the article

Almost always one of three things: the two phases were at different temperatures when combined, the mixing order was wrong, or there was not enough emulsifier. The book's fix is a strict sequential mixing protocol and cycle testing before you call a formula finished.

The book gives a general protocol for order of addition, and warns that it is critical: hydrate gums and thickeners in the water phase first, dissolve primary surfactants with gentle heat if needed, add secondary surfactants and conditioners, cool to below 40 °C before adding heat-sensitive actives such as peptides, vitamins and extracts along with fragrance, adjust pH, then incorporate the preservative last.

For emulsions such as the repair mask, both phases must reach the same temperature — 70–75 °C — before they are combined. Adding a cool water phase to a hot oil phase gives an emulsion that looks fine warm and breaks overnight. Phase B goes into Phase A slowly, under a high-shear mixer, for two to three minutes.

Stability is not something you judge by eye on day one. The book asks for cycle testing — alternating hot and cold for 24 to 48 hours each — plus long-term shelf testing at room temperature, watching for separation, colour change, smell and pH drift over weeks.

Source: The Big Book of Homemade Hair Care — The Shampoo Matrix: Beyond Basic Cleansing · The Intensive Repair Hair Mask · Open the article

Shampoo should sit at pH 4.5–5.5. Conditioning masks and balms go lower, pH 4.0–4.5, because the acidity both seals the cuticle and lets cationic conditioners work.

Hair is naturally slightly acidic, and a product matching it helps the cuticle lie flat. The book sets shampoo at pH 4.5–5.5 and adjusts with citric or lactic acid as one of the last steps in the formula.

Conditioning products go further down. The intensive repair mask targets pH 4.0–4.5, adjusted with a 10% citric acid solution below 35 °C. There are two reasons for the lower figure: the acidic pH helps seal the hair cuticle, and cationic conditioners such as BTMS-50 need it in order to carry the positive charge that makes them deposit on the negatively charged hair shaft. Formulate the same mask at neutral pH and the conditioner simply rinses away.

pH is adjusted after the actives and before, or alongside, the preservative — and it must be measured on the finished, cooled product, since viscosity and temperature both shift the reading.

Source: The Big Book of Homemade Hair Care — The Shampoo Matrix: Beyond Basic Cleansing · The Intensive Repair Hair Mask · Open the article