Shampoo cubes: recipe, production and how to handle the transition period
TL;DR: Shampoo cube is a solid shampoo without preservatives, equivalent to 2-3 bottles of liquid shampoo. There are two types: surfactant (neutral pH, no transition period) and CP soap (alkaline, requires an acid rinse and a transition period of 2-4 weeks). pH is the key difference from body soap.
The shampoo cube is a solid shampoo - no plastic bottle, no preservatives, with a duration of use equivalent to 2-3 bottles of liquid shampoo. The zero-waste trend and interest in natural hair care have moved it from the niche category to mainstream interest.
But there's one crucial thing that distinguishes a shampoo bar from a body wash: pH.
Why is a shampoo bar different from a body wash - and why is it important?
This is the most important thing to know: body soap has a pH of 9-10, while hair and scalp have a pH of 4.5-5.5. Washing your hair with alkaline soap causes coarseness, dullness and possibly breakage. A proper shampoo bar therefore uses different principles - either acidic surfactants or a special formulation with higher conditioning.
- Opening of the hair scales (cuticle) - hair appears coarse and dull
- Potential breakage in chemically treated hair
- Formation of soap deposit in hard water - "wax film“
Shampoo cubes therefore work on a different principle: they either use acidic or neutral surfactants (instead of soap salts from leaching), or formulated as a solid conditioning bar.
There are two types:
1. Surfactant shampoo cubes (recommended type): They contain solid surfactants (SCS, SLSA, Cocamidopropyl betaine) with a naturally acidic or neutral pH. Do not require a transition period, foams well.
2. CP soap shampoo cube: Solid soap from leaching with high content of castor and coconut oil. pH is alkaline - requires acid rinse (vinegar) and transition period.
This page covers both types.
How to make a surfactant shampoo bar — method without lye?
Surfactant shampoo cubes are easier to make, safer (no lye) and do not require a transition period. The pH remains naturally acidic (5.5-6.5), which is ideal for hair.
What are solid surfactants
Solid surfactants are cleaning agents in solid form that can be compressed into sticks:
SCS (Sodium Coco Sulfate): Related to SLS, but derived from coconut oil. Solid form. Good foaming. Softer on the scalp than SLS.
SLSA (Sodium Lauryl Sulfoacetate): Softer variant, large bubbles, popular with sensitive skin.
SCI (Sodium Cocoyl Isethionate): Gentle, creamy, conditioning. The gentlest of the group. Good for dry and coloured hair.
Cocamidopropyl Betaine (CAPB): Amphoteric surfactant - acts as a co-surfactant and conditioner in one. It helps to reduce the irritation of other surfactants.
Recipe: Basic shampoo bar for normal hair
| Yield | ~150 g (2–3 bars) |
|---|---|
| pH | ~5.5–6.5 |
| Difficulty | ★★☆☆☆ |
Ingredients:
- 60 g SCI (sodium cocoyl isethionate) - 40 %
- 45 g SLSA or SCS - 30 %
- 15 g Cocamidopropyl betaine (CAPB) - 10 %
- 15 g conditioner (BTMS-50 or Incroquat BTMS-25) - 10%
- 15 g panthenol or hydrolysed silk - 10%
- 5-7 g essential oil (rosemary, bergamot, ylang ylang)
- Optional: 2 g citric acid for pH adjustment
Procedure:
- SCI and SLSA are powders - mix them in a bowl.
- CAPB is liquid - add it to the powder, mix.
- Melt BTMS-50 in a water bath (melting point ~70 °C), add to the powder.
- Stir until homogeneous - it will resemble dough.
- Press into moulds or shape with hands (with gloves - SCI irritates).
- Allow to cool and set at room temperature - 2-4 hours.
Modifications for different hair types:
- Dry hair: increase BTMS-50 to 15%, add 5 g of argan oil
- Oily hair: reduce BTMS-50 to 5%, add 10 g of corrective (kaolin clay)
- Coloured hair: use SCI as the only surfactant base, omit SCS/SLSA
How to make a CP shampoo bar — method with lye?
CP shampoo cubes are all natural - no synthetic surfactants. For those who prefer a natural soap base, require higher conditioning (higher superfat) and transition management (acid rinse, hard water).
Key recipe properties
CP shampoo cube works like a body soap - by saponifying lye and oils. For hair, the formulation is different than for body soap:
- Castor oil 20-25%: Creates a thick, conditioning lather
- Coconut oil 30-40%: Cleaning power and hardness
- Olive or jojoba 20-30%: Conditioning
- Super fat higher 10-15%: More unsaponified oil conditions the hair fiber
Recipe
Ingredients:
- 175 g coconut oil (35%)
- 125 g castor oil (25 %)
- 125 g olive oil (25 %)
- 75 g shea butter (15 %)
- 66,2 g NaOH (SF 10 %)
- 245 g of water
⚠️ A note on oils: Jojoba and olive oil cannot be substituted in this recipe - have significantly different SAP values (olive 0.134 vs. jojoba 0.069). The substitution would fundamentally change the amount of NaOH needed and could lead to a dangerously lye-heavy soap. If you want to use jojoba oil, recalculate the gram of NaOH in the calculator.
Additives:
- 10 g panthenol (vitamin B5 - conditioning)
- 5 g rosemary essential oil
- 5 g tea tree essential oil (for shine and skin health)
How to bridge the transition period — getting hair used to a new bar?
The CP shampoo cube requires adaptation - the hair has to get used to the alkaline wash and the different conditioning mechanism. The transition period typically lasts 2–4 weeks and is manifested by slight greasiness, „waxiness“ or possibly increased shedding - all normal and transient.
- Oily or heavy hair in the first 1-2 weeks
- "Waxy“ feeling in hard water
- Possibly increased shedding (transient)
How to bridge the transition period:
1. Acid rinse: After each wash with a shampoo cube (CP type), rinse the hair with a solution of apple cider vinegar - 1 tablespoon of 5% apple cider vinegar per 500 ml of water. The rinse closes the hair scales and neutralizes the alkaline film.
2. Soft water: Hard water reacts with the soap shampoo cube and forms deposits. Filter the water or add a pinch of citric acid to the water.
3. Patience: After 3-4 weeks, the hair regulates its natural sebum production and stops being greasy.
What are the benefits of zero-waste shampoo cubes?
One 60-80 g shampoo cube is equivalent to approximately 2-3 bottles of liquid shampoo (250 ml). No plastic bottle, no preservatives (water independent), long shelf life (12-18 months) and suitable for travelling without liquid limit.
The shampoo cube is ideal for travel - it does not count towards the liquid limit in your hand luggage.
Frequently asked questions
What type of shampoo cube is best for beginners? Surfactant cube (without lye) is safer and does not require a transition period. It is ideal for a first project. CP cube (with lye) is for advanced soapmakers who already have experience with the chemistry of lye.
How long will the transition period last - when will my hair normalize? CP shampoo cubes typically require 2-4 weeks. Greasiness and „waxiness“ of the first 1-2 weeks are normal - the hair regulates its natural sebum production. An acid rinse (vinegar) speeds up the process.
Can I buy ready-made surfactants (SCI, SLSA) in the Czech Republic - where? Yes, available in soap and cosmetics e-stores. SCI and SLSA are common raw materials. Price: 200-500 CZK per 100-500 g, depending on quality and industry.
Will my CP shampoo cube smell like liquid shampoo? The essential oils in the cube last, but the scent is more discreet than in liquid shampoo. Higher doses of EOs (5-10g per 500g of oils) will enhance the scent but may irritate the scalp.
How do CP and surfactant cube differ in how they feel on the hair? The CP cube has a more foaming and conditioning effect due to the high content of castor oil. Surfactant cube foams stronger, is more cleansing but less conditioning - ideal for oily hair.
What is the difference between a shampoo bar and a conditioner bar? The shampoo cube cleanses (contains surfactants), the conditioner moisturizes. Often used together - shampoo on the roots, conditioner on the lengths. They can also be combined - e.g. surfactant cube + jojoba oil on the ends.
See also:
- Soap additives - panthenol, silk and conditioners
- Essential Oils in Soap - selection for hair care
- EU regulations - a shampoo bar is a cosmetic product, not a soap
⚠️ Recipe disclaimer
This recipe was created or revised with the help of artificial intelligence tools and has undergone NaOH gram recalculation. Nevertheless, we recommend verifying lye amounts in an independent calculator (e.g. SoapCalc or Brambleberry). Working with sodium hydroxide requires protective equipment — see Lye safety. Information is for educational purposes; the manufacturer is not liable for damages resulting from their use.
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