Among the various types liquid detergents sodium laureth sulfate (SLES) detergents are some of the most easy to formulate, but if not well understood can end up becoming very difficult and complex, especially when it comes to achieving the desired thickness or viscosity for the product.

Detergent crafters have very few options when it comes to thickening SLES liquid detergents.  In most cases, thickening is done using common salt (NaCl) and the result is strongly dependent on the pH of the detergent mixture.

SLES formulations are in most cases highly alkaline with pH commonly above 12.0. When salt is added at such high pH levels thickening is less likely to occur since the chemistry of the mixture is too alkaline. Therefore pH of the mixture must be adjusted (to about 6.0) using citric acid before thickening with salt.

SLES detergent formulation with all components already added
Citric acid
Salt (NaCl)
Weighing scale
pH meter

Water

Thickening SLES Detergent With Salt

1. Pour 940g of SLES detergent formulation into a bowl or beaker.
2. Dissolve 10g citric acid in about 50g water and add a little at a time while checking with the pH meter (stir gently each time) until the pH is adjusted to 6.0
3. Add 5g of salt and stir vigorously until the detergent thickens into a white foamy mixture.
4. Set aside overnight for suds to clear out.