Sodium Lauryl Sulfoacetate (SLSA), 100 g

Sodium lauryl sulfoacetate (SLSA)

Sodium lauryl sulfoacetate, abbreviated SLSA, is a powder surfactant that produces dense and stable foam even in solid and anhydrous products. It is therefore used primarily in bath bombs, foaming bath bars, solid shampoos and syndet soaps, where liquid surfactants are difficult to process.

Compared to the commonly used Sodium Lauryl Sulfate, it has a lower irritation potential. Its molecule contains a sulfoacetate group instead of a sulfate group, yet the foam remains rich and creamy. It is therefore also suitable for rinse-off products for sensitive and children's skin.

Key properties

• Rich foam – dense, creamy foam with small bubbles that lasts a long time in the bath.
• Sulfate-free – a product containing it can be labelled as sulfate-free, while foaming performance is comparable to sulfate surfactants.
• Powder form – introduces no water into the formula, which is decisive for solid and powder products that would otherwise activate or disintegrate.
• Anionic character – combines with anionic, amphoteric and non-ionic surfactants, making it suitable as a primary surfactant or as a co-surfactant in solid shampoos.
• Readily biodegradable – meets the criteria for ready biodegradability according to OECD 301.

Use in formulation

In anhydrous products, SLSA is simply blended with the other dry ingredients. The recommended usage level is 1 – 50 %. In bath bombs with baking soda and citric acid, it is used at the lower end of the range. In foaming bath bars and solid shampoos, the proportion is significantly higher, as it is the primary foam carrier and forms the backbone of the product. The powder becomes sticky when moistened, so the binder (oil, butter, glycerin) is added gradually and the mass is pressed or shaped while wearing gloves.

In water, SLSA disperses and dissolves only partially, so producing a clear liquid shampoo from it is difficult. It is better suited to creamy shower products, powder facial cleansers or blends where cloudiness is not a concern. It is added to the water phase or during the cooling phase at temperatures up to 70 °C and mixed until the powder disperses without lumps. The recommended pH of the finished formulation is 5 – 7.

Suitable for products such as

• Bath bombs and foaming salts – foam in the bath is produced without liquid surfactants that would prematurely activate the bomb.
• Foaming bath bars – SLSA is the primary ingredient here; without it the bar does not foam.
• Solid shampoos – on its own or combined with Sodium Cocoyl Isethionate, which adds creaminess.
• Syndet soaps – solid cleansing bars without saponification, with a pH close to skin.
• Powder cleansers for face and body – loose preparations that activate only when water is added in the palm.
• Rinse-off children's and intimate cosmetics – where a low irritation potential matters more than maximum foaming.

Good to know

SLSA belongs in rinse-off products. Surfactants of this type are not commonly used in leave-on products.

In solid shampoos, it is advantageous to combine it with a milder surfactant, such as Sodium Cocoyl Isethionate or Cocamidopropyl Betaine. SLSA provides foam volume and quick lathering, while the second surfactant softens the washing sensation and reduces scalp tightness. A higher proportion of SLSA alone can strip the hair of oils.

The powder is sensitive to moisture. After absorbing ambient humidity it clumps and loses its free-flowing properties, which in bath bombs can trigger a premature reaction. Pack loose mixtures in airtight containers.

The powder is white, so it will not affect the shade of a coloured bomb.

Frequently asked questions