Distilled water

What is it? Distilled water is water that has been distilled to remove impurities like minerals and salts.
INCI Aqua
Appearance Funnily enough, it looks just like water 😝
Usage rate Up to 100%
Texture It feels just like water
Scent Nothing
Absorbency Speed Fast
Approximate Melting Point 0°C (32°F)
pH ~5.8 (read this to learn more)
Solubility Water
Why do we use it in formulations? We use distilled water in our formulations because it removes the variable of whatever might be in tap or mineral water. Learn more here.
Do you need it? Yes
Strengths Inexpensive, generally easily available, low-variable water.
Weaknesses It doesn’t come out of your tap?
Alternatives & Substitutions De-ionized water is a good alternative, and tap water will likely work in a pinch assuming your tap water is clean and not extremely mineral heavy. You can learn about other alternatives here.

If you’d like to fancy up a formulation you can swap some of the water for other watery-type ingredients like aloe vera juice, witch hazel distillate, or hydrosols.

How to Work with It Use as the formulation directs—it’s an extremely flexible ingredient!
Storage & Shelf Life Stored somewhere cool, dark, and dry, distilled water should last indefinitely.
Tips, Tricks, and Quirks Distilled water is not sterile—it simply lacks the minerals and salts that can be found in tap water or mineral water.
Recommended starter amount 4L (1 gallon)
Where to Buy it I recommend buying it from your local grocery store; you’ll be buying it roughly 4L/1 gallon at a time (at least) and you don’t want to pay to ship that!

Some Formulations that Use Distilled Water

Isododecane

What is it? Isododecane is an extremely lightweight, very volatile (fast evaporating) liquid. It is an emollient and solvent that is frequently used in cosmetics. It gives a fantastic dry-touch finish very quickly.
INCI Isododecane
Appearance Water-like clear liquid.
Usage rate Up to 20%
Texture Thin liquid with great slip, very fast evaporation, and great leftover skin feel.
Scent Nothing noticeable
Absorbency Speed Very fast evaporation
Solubility Soluble with silicones, hydrocarbons, isoparaffin, and mineral spirits.
Why do we use it in formulations? Isododecane is incredibly useful in liquid cosmetics—I’d call it indispensable. It is an excellent choice for liquifying cosmetics that we need to set quickly (liquid lipstick, liquid eyeliner, etc.) as it sets quickly but spreads beautifully before setting. It is also an excellent solvent for strong film-forming silicone resins like trimethylsiloxysilicate.
Do you need it? If you want to make liquid cosmetics it is necessary.
Refined or unrefined? It only exists as a refined product.
Strengths Fantastic fast-evaporating emollient.
Weaknesses Not natural if that is a priority for you. Low flash point (43°C/109°F).
Alternatives & Substitutions Nothing, really. Cyclomethicone is also slippy and volatile, but doesn’t have the same dry-touch finish as isododecane and that finish can be absolutely instrumental to the performance of cosmetics like liquid lipsticks and eyeshadow primers.
How to Work with It Include it in the cool down phase of your recipes. If necessary, very briefly heat it to incorporate it into pre-melted waxes. Keep the flash point (43°C/109°F) in mind! Don’t forget to replace the lid promptly—it will evaporate if left uncovered!
Storage & Shelf Life Stored somewhere cool, dark, and dry, isododecane should last at least two years.
Tips, Tricks, and Quirks Its weightless feel and fast evaporation speed make it an excellent addition to many products where we want great spreadability but no residual weight—think cosmetics and hair products.

Isododecane is a great solvent, which makes it fantastic for cleaning up hard-to-clean messes! I find it brilliant for cleaning up stubborn smudges of colourful cosmetics.

Recommended starter amount 250mL (8fl oz)
Where to Buy it  Buy it from an online DIY ingredient supplier.

Some Formulations that Use Isododecane

Arrowroot Starch

What is it? Arrowroot starch (or arrowroot powder) is a fine, starchy powder.
INCI Maranta Arundinacea Root
Appearance Fine white powder
Usage rate Up to 100%
Texture Soft and silky
Scent Nothing noticeable
Solubility Insoluble
Why do we use it in formulations? In anhydrous products it helps reduce the greasy/oily skin feel, and in higher concentrations it can give the entire product a powdery, dry-touch finish and contribute to thickening.

In powdered cosmetics it acts as a diluent and improves slip.

It can also be used in dusting powders, or even used as-is for a dusting powder.

Do you need it? No.
Strengths Ultra silky, inexpensive ingredient.
Weaknesses I can’t think of any, though it is easily replaced.
Alternatives & Substitutions Other starches like corn and wheat work well in its place.
How to Work with It Include it in the heated or cool down phase, or the grinding phase of powdered products.
Storage & Shelf Life Stored somewhere cool, dark, and dry, arrowroot starch should last up to three years.
Tips, Tricks, and Quirks Despite all my best efforts I’ve never been able to bake arrowroot biscuits that taste like the delicious arrowroot biscuits we give to kids. If you have a brilliant recipe, please get in touch!
Recommended starter amount 100g (3.3oz)
Where to Buy it  Buy it from an online DIY ingredient supplier or Amazon.

Some Formulations that Use Arrowroot Starch

Citric Acid

What is it? An inexpensive white crystalline alpha hydroxy acid.
INCI Citric Acid
Appearance White crystals; looks like table salt or white sugar.
Usage rate It depends. If part of bath bombs or other “fizzing” products it can be used upwards of 25%. If being used as a pH adjuster it is used at significantly lower rates (less than 1%).
Scent Sour, tangy.
pH 2.2
Solubility Water
Why do we use it in formulations? In bath bombs and other fizzing products it forms all or most of the acidic part of the reaction that causes the fizz. It can also be used to lower the pH of products as part of a 50/50 solution of citric acid and distilled water.
Do you need it? I’d recommend it; it’s an accessible and inexpensive acid that doesn’t have the characteristic smell of vinegar.
Strengths Highly effective, inexpensive acid.
Weaknesses I can’t think of any that aren’t inherent to strong acids (potential to be irritating, sour tasting, etc.).
Alternatives & Substitutions In bath bombs it’s very difficult to adequately substitute citric acid. I have no suggestions at this time.

For pH adjusting a lactic acid solution is a good alternative.

How to Work with It In bath bombs and other primarily powdered fizzing products, include citric acid with the rest of the powdered ingredients.

For pH adjusting, create a 50/50 solution of citric acid with distilled water (by weight!) and use single drops to adjust the pH, re-checking the pH between additions. (For example, combine 5g each citric acid and distilled water.)

Take care not to inhale.

Storage & Shelf Life Stored somewhere cool, dark, and dry, citric acid should last at least three years.
Tips, Tricks, and Quirks Citric acid is an alpha hydroxy acid along with acids like lactic and glycolic.
Recommended starter amount If you want to make bath bombs I’d start with at least 500g (1lb). If it’s just for pH adjusting 30g (1oz) will be more than enough.
Where to Buy it  Buy it from an online DIY ingredient supplier or Amazon.

Some Formulations that Use Citric Acid

Penstia™ powder

What is it? Penstia™ powder is a white powder additive for our emulsions and makeup to improve slip and feel.
INCI Adipic Acid/Neopentyl Glycol Crosspolymer
Appearance Clumpy white powder
Usage rate 3–5%
Scent None
Solubility Insoluble
Why do we use it in formulations? Penstia™ powder makes our products feel more luxurious and higher end—it almost feels a bit like cheating! It adds a silky, creamy feel to emulsions and makeup. It is made up of porous spheres that roll across the skin on application, giving excellent slip. It also helps reduce sensations of tackiness and greasy/oiliness.
Do you need it? No, it’s definitely a luxury ingredient.
Strengths Stunning skin feel!
Weaknesses Poor availability outside North America.
Alternatives & Substitutions There’s nothing that’s quite like Penstia™ powder so it can be a bit tricky to substitute. If you’re looking to improve the slip of a recipe you could try including 1% dimethicone 350 to the oil phase. If you don’t have Penstia™ powder you can generally leave it out without drastically impacting the recipe. In a lotion you can substitute Penstia™ powder with more water. In a cosmetics you could replace it with more sericite mica.
How to Work with It In emulsions, include it in the cool down phase. It is not heat sensitive (so you could add it at the same time you combine your heated phases if you like), but it will not melt in the oil phase or dissolve in water, and that can be a bit disconcerting if you’re waiting for it to dissolve.
Storage & Shelf Life Stored somewhere cool, dark, and dry, Penstia™ powder should last 1.5–2 years.
Tips, Tricks, and Quirks Try incorporating Penstia™ powder into anything you find sticky!
Recommended starter amount 30g (1oz)
Where to Buy it  Buy it from Windy Point (Canada) or Lotion Crafter (USA).

Some Formulations that Use Penstia™ powder

Baking Soda

What is it? Baking soda is an alkaline (basic) abrasive powder.
INCI Sodium bicarbonate
Appearance White powder
Usage rate It depends on the use; probably no more than 60% in most cases, and those cases would be bath products where it is highly diluted (in bath water) when used.
Texture Abrasive semi-fine powder
Scent A bit salty & bitter
pH 9
Solubility Water
Why do we use it in formulations? It reacts well with acids like citric acid to create fizzy products like bath bombs, fizzing bath salts, and fizzing scrubs. It can also be a useful abrasive as a household cleaner.

Baking soda is too basic and too abrasive to be regularly used on the skin—read more on this here. For this reason, I do not recommend using it unreacted in facial scrubs or deodorants. It can be fine as an ingredient in bath salts for occasional use as it would be highly diluted in bath water and is unlikely to be used on a daily basis.

Do you need it? Not unless you want to make fizzy bath things.
Refined or unrefined? All baking soda is refined.
Strengths Excellent for creating fizzy bath products.
Weaknesses Too basic for use in skincare products.
Alternatives & Substitutions When you need baking soda it’s really the only thing that’ll do. Good thing it’s inexpensive and widely available!
How to Work with It When blending it with acids like citric acid and Cream of Tartar be sure to keep the mixture as dry as possible until the moment of use to prevent pre-emptive fizzing.
Storage & Shelf Life Stored somewhere cool, dark, and dry, baking soda should last indefinitely.
Tips, Tricks, and Quirks Baking soda is much cheaper if purchased from an online store in bulk rather than at the grocery store, so if you really like making bath bombs I’d recommend going online. DIY suppliers typically have it for good prices, and so does Amazon.
Recommended starter amount For bath bombs, I’d recommend at least 500g (1.1lb). For pH adjusting, 30g (1oz) would be enough.
Where to Buy it  Buy it from an online DIY ingredient supplier or Amazon.

Some Formulations that Use Baking Soda