"A shampoo bar is not a soap bar used on hair. It is a completely different formulation. Get that right first.
"KaiRenner26th of April 2026
Why Shampoo Bars Are Different from Soap
A cold-process shampoo bar uses a different oil profile than body soap. The goal is high-lather, low-conditioning — the opposite of a luxury body bar. High-lauric oils (coconut, palm kernel) create abundant lather and cleansing ability. Castor oil (up to 10%) boosts lather quality dramatically. Superfat is kept at 0 to 3% — too much conditioning oil leaves hair greasy and dull. Sodium hydroxide (lye) is the essential chemical that saponifies the oils.
0to 3 Percent
6to 8 Weeks
Calculate Your Lye and Water with a Soap Calculato
Never estimate — use Soap Calc or SoapMakingFriend for every batch.
Calculate Your Lye and Water with a Soap Calculator
Enter your oil weights into a lye calculator (soapcalc.net or soapmakingfriend.com). Set superfat at 2%. The calculator outputs the exact sodium hydroxide and water amounts for your oil blend. Never estimate lye quantities — errors produce bars that are either lye-heavy (caustic) or over-superfatted (greasy). Print the calculation and keep it with your batch records.
Mix the Lye Solution Safely
Add lye to water — never water to lye — in a well-ventilated space.
Mix the Lye Solution Safely
Always add sodium hydroxide to water, never reverse. The reaction is exothermic — the solution heats to 200°F and releases caustic fumes. Work outdoors or in a well-ventilated space with eye protection, gloves, and long sleeves. Stir until fully dissolved. Allow to cool to 90 to 110°F before combining with oils.
Combine Oils and Lye at Trace
Blend with a stick blender to trace, then pour into molds.
Combine Oils and Lye at Trace
Melt hard oils (coconut oil) and combine with liquid oils to reach 90 to 110°F. Pour lye solution into oils (not reverse). Blend with a stick blender in short bursts until trace — the batter thickens to a pudding-like consistency where a drizzle holds on the surface. Pour into molds immediately. Shampoo bar batter traces faster than body soap due to the high coconut oil content.
A Basic Shampoo Bar Formula (500g batch)
350g coconut oil (70%) — cleansing, high lather
50g castor oil (10%) — lather booster
100g olive oil (20%) — conditioning, reduces harshness
Sodium hydroxide — calculated from lye calculator
Distilled water — calculated from lye calculator
Safety: gloves, goggles, long sleeves, ventilation
Hair Needs an Adjustment Period Switching from commercial shampoo (which contains silicone and sulfate detergents) to a shampoo bar causes a 2 to 4 week adjustment period where hair feels waxy or heavy. This is normal — the scalp is adjusting its sebum production. Rinse with diluted apple cider vinegar (1 tablespoon per cup of water) as a conditioning rinse to help during the transition period.
"The bar will work better on week six than on week two. Both the bar and your scalp need time.
"KaiRenner26th of April 2026