NATRASORB® BATH

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

Lactic acid

What is it? Lactic acid is an alpha hydroxy acid that is used for pH adjusting and for creating skincare formulations that chemically exfoliate the skin. Humans have been embracing lactic acid in skincare for centuries—lactic acid is part of the magic of a milk bath! Lactic acid is considered to be more gentle than its sister AHA, glycolic acid.

Health Canada regulations stipulate that all formulations that contain 3% or more lactic acid must bear these warnings:

  • “Use only as directed.”,
  • “Avoid contact with the eyes.”,
  • “If irritation persists, discontinue use and consult a physician.”,
  • “It is recommended that prior to exposure to the sun, users cover areas where AHAs have been applied with sunscreen.”,
  • “Contact of the product with the skin must be of limited frequency or duration.”

Lactic acid is part of the skin’s natural moisturizing factor (NMF), compromising 10–12%.

INCI Lactic acid
Appearance It is often sold as an 88% or 90% liquid solution; this is is a clear, slightly viscous fluid.
Usage rate For pH adjusting, generally less than 1% (though usually less than 0.5%). For chemical exfoliation, no more than 10%, though I’d recommend starting with less.

Health Canada regulations limit non-professional use of lactic acid to 10%, with a pH equal to or greater than 3.5. Any concentrations higher than 10% are limited to professional use.

“The CIR Expert Panel evaluated the scientific data and concluded that … Lactic Acid… [was] safe for use in cosmetics and personal care products at concentrations of 10% or less, at final formulation pH of 3.5 or greater, when formulated to avoid increasing sun sensitivity or when directions for use include the daily use of sun protection.” (Source)

Scent Sour, tangy
pH 0.6
Solubility Lactic acid is water soluble.
Why do we use it in formulations? Lactic acid lowers the pH of our formulations; it is often used at very low concentrations to adjust pH.

In higher concentrations lactic acid acts as a chemical exfoliant and skin care active.

Some skincare benefits from using lactic acid include:

Do you need it? No, but it is very useful if you are interested in making high-performance skin care.
Refined or unrefined? The lactic acid used in cosmetics and skin care is always a refined product.
Strengths Potent pH adjustor, occurs naturally in the skin, mild as far as acids go.
Weaknesses Like all potent ingredients, it requires care when formulating with it.
Alternatives & Substitutions Other pure acids (citric acid is typically the most readily available) will work for pH adjusting, though it won’t be a 1-for-1 swap; you’ll need to test and adjust the formulation using the new acid.

Other alpha hydroxy acids like mandelic acid and glycolic acid can also be used to create exfoliating products. As with pH adjusting, this will not be a 1-for-1 swap; you will need to test and adjust the pH of the formulation to ensure it is safe.

How to Work with It Wear gloves; concentrated lactic acid is very acidic.

I’d say you need a digital pH meter to formulate products where lactic acid is a feature ingredient. The precise pH of the formulation is very important for safety, and strips aren’t very precise.

Lactic acid can be hot or cold processed.

Ensure the final pH of the product is 3.5 or greater: if you are creating an exfoliating product you will almost certainly need to raise the pH of your formulation (I use a 10% sodium hydroxide solution). As lactic acid has a pKa of 3.86, I recommend aiming for a pH close to 3.86 for optimal performance. Learn more about pKa with this fabulous article from Lab Muffin!

If following a formulation that calls for lactic acid, make sure you pay attention to the concentration called for in the formulation. If yours is a different concentration, adjust the lactic acid and water content of the formulation if required to end up with the same final percentage of lactic acid.

Storage & Shelf Life Stored somewhere cool, dark, and dry, lactic acid should last at least 2 years.
Tips, Tricks, and Quirks I recommend re-packaging your lactic acid in a glass bottle with a dropper top lid for easy dispensing.

You can create a buffer with lactic acid and sodium lactate in a 1:2 ratio, which should hold a formulation around a pH of 4. Learn more here.

Lactic acid does occur in milk, but cosmetic grade lactic acid is synthesized (and vegan).

Do not use lactic acid (or other AHAs) together with retinol. Do not apply to irritated skin.

Recommended starter amount 30mL (1fl oz) for pH adjusting; 60mL if you intend to use it as a chemical exfoliant.
Where to Buy it  Buy it from an online DIY ingredient supplier or Amazon.

Some Formulations that Use Lactic acid

L-Arginine

What is it? L-Arginine is an amino acid with a basic pH—it’s useful for boosting the pH of our formulations.

It has moisturizing, skin conditioning, and barrier boosting properties, but if used at pH-adjusting amounts those benefits are unlikely to be noticeable in a finished product. The formulations I’ve found that use it as an active ingredient use it at 0.5–2%. Your mileage may vary, though! Depending on the formulation you may be able to work in enough L-Arginine to get skin benefits and a perfect pH.

INCI Arginine
Appearance White crystaline powder
Usage rate As needed to get the pH of your formulation where you want it; generally less than 1%.
Scent Nothing noticeable at pH-adjusting levels.
pH A 10% L-Arginine solution has a pH between 10.5–12.
Solubility L-Arginine is water-soluble.
Why do we use it in formulations? L-Arginine is used to raise the pH of our formulations; I find I’m most likely to need it when working with acid-based natural preservatives that dramatically lower the pH of a formulation.
Do you need it? No, but you should have something to raise the pH of your formulations and this L-Arginine is a good choice if you can get it.
Refined or unrefined? L-Arginine only exists as a refined ingredient.
Strengths An easy, gentle ingredient for raising the pH of our formulations.
Weaknesses It’s not terribly easy to find.
Alternatives & Substitutions A 10% NaOH (lye) solution or triethanolamine will work, but not in the same amounts—if you’re following a formulation that includes L-Arginine to adjust the pH you’ll have to test and adjust with the new base/pH raising ingredient.
How to Work with It L-Arginine isn’t super strong, so you can add the straight powder to some formulations, or make a dilution—whatever works for each formulation. I keep a 10% solution and the pure powder on hand.
Storage & Shelf Life Stored somewhere cool, dark, and dry,
Tips, Tricks, and Quirks Cosmetic grade L-Arginine is not the same as food, dietary supplement, or pharmaceutical grade. I’m unsure if L-Arginine purchased from the drug store would be a good workaround if you can’t purchase cosmetic grade L-Arginine.
Recommended starter amount 30g (1.06oz)
Where to Buy it I’ve only found cosmetic grade L-Arginine at Skin Chakra (Germany) and Essential Wholesale (USA).

Some Formulations that Use L-Arginine

Silicone Elastomer (Dimethyl Siloxane Elastomer, Fumed Silica)

What is it? Silicone elastomer is a super fine, slippy, gorgeous powder ingredient that improves all kinds of colour cosmetics. It helps with oil control, improves skin feel, and helps disguise imperfections.

If you’ve used Silica Dimethyl Silylate and Silica Microspheres, I’d say silicone elastomer exists somewhere between them. It’s slippy like silica microspheres, but thickens a bit more like Silica Dimethyl Silylate (SDS).

INCI Dimethyl Siloxane Elastomer, Fumed Silica (generic)
Appearance Ultrafine white powder
Usage rate Up to 20%
Texture Ultra-smooth and rich
Scent None
Solubility Insoluble, but so fine that it is indistinguishable.
Why do we use it in formulations? Basically, it makes everything better! It blurs fine lines, improves slip, and can improve wear time by helping control sebum. It improves colour/pigment payoff and makes our cosmetics feel more expensive/luxurious. TKB lists the usage rate as up to 20%, but I’ve noticed big differences including it at less than 1%!
Do you need it? No, but if you love making high-end colour cosmetics I definitely recommend it.
Refined or unrefined? Silicone Elastomer only exists as a refined product.
Strengths It’s a potent and highly effective way to level up your cosmetic formulations.
Weaknesses  I have only found silicone elastomer for sale from TKB Trading in the USA.  They ship internationally, but I know that can get expensive.
Alternatives & Substitutions Silica Microspheres would be my first suggestion. Keep in mind that when you’re making substitutions in cosmetics even very small changes can dramatically impact the performance, wear time, and consistency of the cosmetic. I worked on a formulation that included 0.25% Silica Dimethyl Silylate (SDS), which didn’t work—I switched that 0.25% to silicone elastomer and it was perfect.
How to Work with It Avoid inhaling silicone elastomer; I find it is far less floaty/inhalation prone than Silica Dimethyl Silylate and Silica Microspheres.
Storage & Shelf Life Stored somewhere cool, dark, and dry, silicone elastomer should last three years or more.
Tips, Tricks, and Quirks Read the reviews for this product on TKB Trading to get some fun ideas for using it!
Recommended starter amount 30g (1.06oz) will last a long time!
Where to Buy it  I have only found silicone elastomer for sale from TKB Trading.

Some Formulations that Use Silicone Elastomer

Glycol distearate

What is it? Glycol distearate is “the diester of ethylene glycol and stearic acid.” It can function as an emulsifier and emulsion stabilizer but tends to be primarily used as an opacifier/pearlizer for surfactant products. Glycol distearate lends a really lovely creamy, pearlescent appearance to surfactant products without thickening them or negatively impacting lather (as added fats do).

Glycol distearate is often sold with some variation on the word “pearl” in the name, so make sure you’re searching by INCI when looking for this ingredient.

INCI Glycol distearate
Appearance Medium-sized flat white flakes
Usage rate 1–4%
Texture Brittle, snappable flakes
Scent Nothing noticeable.
Approximate Melting Point 60–63°C (140–145°F)
Charge Non-ionic
Solubility Oil-soluble, self-emulsifies in water
Why do we use it in formulations? Glycol distearate gives opacity and some pearlescence to our surfactant formulations without diminishing lather.
Do you need it? If you want to make an opaque, creamy-looking body wash/face wash/shampoo that still has rich, plentiful lather, you’ll want some glycol distearate.
Refined or unrefined? Glycol distearate only exists as a refined product.
Strengths Glycol distearate is a very effective way to opacify surfactant products without negatively impacting lather.
Weaknesses It can be harder to find, depending on where you live.
Alternatives & Substitutions Glycol distearate is unlikely to be a lynchpin ingredient in a surfactant formulation, so you can likely just replace it with more distilled water if you don’t have it. This will mean the end product is not opaque, but the function of the product should not be massively impacted.

I’ve had good results using Glyceryl Stearate SE instead of glycol distearate with two main modifications. The first is that you’ll need to reduce the thickener in the formulation as Glyceryl Stearate SE contributes much more thickening than glycol distearate does—a one-for-one swap without any other adjustments will make for a noticeably more viscous end product. And, for better pearlescent-ness, I’d include a small amount (perhaps 0.25–0.5%) of a shimmery mica of your choice.

If you can find a liquid pearlizing ingredient that contains Glycol distearate you can likely tweak the formulation to work with that instead. Make sure you are reading through the documentation on that ingredient (specifically the recommended usage rate) to see how much you are generally supposed to use and go from there.

How to Work with It Glycol distearate must be melted, so include it in a heated phase. I’ve used it in heated oil and heated water phases; both work, so let your formulation guide you.
Storage & Shelf Life Stored somewhere cool, dark, and dry, Glycol distearate should last at least two years.
Tips, Tricks, and Quirks It is also possible to purchase products that contain Glycol distearate blended with other ingredients like Laureth-4, Cocamidopropyl Betaine, Sodium Laureth Sulfate, and Cocamide MEA. These are usually sold as pearlizing agents for surfactant products. Make sure you are watching the INCI of what you are purchasing, as these ingredients are not necessarily directly interchangeable.

While many suppliers list glycol distearate as an emulsifier, I have not found it makes a suitable replacement for emulsifying waxes like Polawax, Olivem 1000, Glyceryl Stearate SE, etc.

Recommended starter amount 30g (1.06oz)
Where to Buy it  Buy it from an online DIY ingredient supplier or Amazon.

Some Formulations that Use Glycol distearate

d-Limonene

What is it? d-Limonene (citrus terpenes) is a natural solvent derived from citrus peels. I mostly use it in cleaning applications. It is a terpenoid hydrocarbon found in many essential oils. It can also be found as an adulterant in low quality essential oils (especially citrus ones).
INCI d-Limonene
Appearance Clear liquid
Usage rate Up to 100%, though that would be a very strong cleaning solvent! Recommendations for incorporation in formulas are typically 20% or less.
Texture Thin, volatile liquid
Scent Citrusy—orange/lemon
Approximate Melting Point -74ºC to to -96.9ºC (-101.2°F to -142.6°F)
Solubility Oil, alcohol
Why do we use it in formulations? d-Limonene is an excellent de-greasing solvent that also adds a fresh, citrusy scent to our products. I have only used it in cleaning products.
Do you need it? It’s great if you intend on making your own cleaning products, but beyond that I wouldn’t bother.
Refined or unrefined? d-Limonene only exists as a refined product.
Strengths Fantastic natural de-greasing solvent that also smells great.
Weaknesses Can degrade/break down some plastics in high concentrations with extended exposure.
Alternatives & Substitutions Citrus essential oils are typically high in d-limonene; sweet orange, grapefruit, clementine, bitter orange, tangerine, and satsuma essential oils can all contain upwards of 90% d-limonene. Those essential oils seem like a reasonable place to start, though they are all likely to be more expensive than isolated d-limonene. Out of those essential oils sweet orange, satsuma, and tangerine are not photosensitizing, so I would likely choose one of those.
How to Work with It Include in the oil phase of your products or solubilize into the water phase. Avoid heating as the flash point is quite low (43–49°C/109–120°F).
Storage & Shelf Life Stored somewhere cool, dark, and dry, d-limonene should last at least two years.
Tips, Tricks, and Quirks Try solubilizing some d-limonene with vinegar for an excellent cleanser.
Recommended starter amount 100mL (3.3fl oz)
Where to Buy it  Buy it from an online DIY ingredient supplier or Amazon.

Some Formulations that Use d-Limonene