What is it? NATRASORB® BATH is a modified tapioca starch manufactured by Nouryon. Its INCI is just Tapioca Starch, but it performs very differently from plain grocery store tapioca starch in bath formulations.

NATRASORB BATH starch is able to absorb and carry large quantities of oils and anhydrous liquids, such as bath oils. The starch is processed in a manner that creates unique ‘pockets’ that can carry the oils essentially in a solid, powder form. NATRASORB BATH starch is hydrophilic so that once the starch comes in contact with water, it immediately dissolves, releasing loaded oils, fragrances and/or emulsifiers, dispersing them into the warm water. The starch itself provides a soft feel to the bath water, but does not settle or leave a film.” – Nouryon

INCI Tapioca Starch
Appearance Ultra lightweight fluffy white powder
Usage rate Nouryon states that NATRASORB® BATH is able to absorb up to 16% of its weight in mineral oil without any change of appearance, and up to 19% without loss of free flow.

With this in mind, if you wanted to include 1% fragrance oil or essential oil and 2% polysorbate 80 in a formulation, roughly 20% NATRASORB® BATH should be sufficient to ensure the final formulation remains free-flowing (aka doesn’t clump up).

Texture Smooth, light, fluffy
Scent Nothing noticeable
pH 6.5–8
Solubility Water soluble
Why do we use it in formulations? The most common use for NATRASORB® BATH is in creating bath salts that don’t seize up over time. If you’ve ever made bath salts with a fragrance oil, but without an ingredient like NATRASORB® BATH, you’ve likely experienced them turning into a brick after a week or so. Bummer.

NATRASORB® BATH allows us to create free-flowing bath salts and other formulations where both oil adsorbency and water solubility are required (like haircare applications!).

Do you need it? If you want to make bath salts I’d say you need either NATRASORB® BATH or Dendritic Salt.
Refined or unrefined? NATRASORB® BATH only exists as a refined product.
Strengths Excellent at ensuring bath salts remain free-flowing.
Weaknesses I can’t think of anything.
Alternatives & Substitutions Dendritic salt is a good alternative for creating bath salts that don’t clump.
How to Work with It When making bath salts, combine NATRASORB® BATH with fragrance and a solubilizer until uniform (I do this with gloved hands, as if I was rubbing butter into biscuit dough). Once uniform, blend that mixture with the remaining ingredients in the formulation.
Storage & Shelf Life Stored somewhere cool, dark, and dry,
Tips, Tricks, and Quirks 15g (half an ounce) of Natrasorb is approximately 250mL (1 cup) by volume!
Recommended starter amount 50–100g
Where to Buy it  Buy it from an online DIY ingredient supplier (USA / Canada / UK / NZ). Beware of substantially cheaper products with an INCI of tapioca starch; they may just be plain grocery store tapioca starch without any of the ability to hold oil.

Some Formulations that Use NATRASORB® BATH


Posted on

November 16, 2023