Tetrahexyldecyl Ascorbate (vitamin C)

What is it? Tetrahexyldecyl Ascorbate is a stable, oil-soluble form of vitamin C, offering the benefits of L-ascorbic acid without the formulation challenge.

Mine is from Simply Ingredients and their product page has lots of great information; check it out to learn more.

INCI Tetrahexyldecyl Ascorbate
Appearance Clear oily liquid
Usage rate 0.5–20% (I’ve found upper limits ranging from 2 to 20%; the listed range is from Simply Ingredients)
Scent Nothing noticeable
Approximate Melting Point Liquid at room temperature
Solubility Oil
Why do we use it in formulations? Like L-ascorbic acid, Tetrahexyldecyl Ascorbate can help reduce pigmentation and age spots, increase collagen synthesis, and is a powerful antioxidant.

Unlike L-ascorbic acid, Tetrahexyldecyl Ascorbate is oil soluble (so it can be used seamless in anhydrous formulations) and it’s stable, so you don’t have to worry about pH and oxidization when formulating with it. It’s also less irritating than L-ascorbic acid.

Do you need it? No, but I’d consider it a great luxury ingredient.
Refined or unrefined? Tetrahexyldecyl Ascorbate only exists as a refined ingredient.
Strengths It works and it’s easy to work with!
Weaknesses It’s really expensive.
Alternatives & Substitutions A different oil-soluble format of vitamin C like L-Ascorbyl Palmitate would be a good place to start.

Depending on the formulation you could look at other forms of vitamin C, like Sodium Ascorbyl Phosphate, Magnesium Ascorbyl Phosphate, or L-ascorbic acid.

Different formats of vitamin C will have different formulation requirements and usage rates, so make sure you are doing your research to ensure compatibility, safety, and success.

Depending on the formulation and role Tetrahexyldecyl Ascorbate is meant to play in it, you could also try replacing it with a different ingredient (or ingredients) that offer similar benefits. For example, Niacinamide (Vitamin B3) also has skin brightening benefits, and Tocopherol (Vitamin E) is a great antioxidant.

How to Work with It A pH of 3–6 is recommended for hydrous formulations. Avoid prolonged heat, Sandream Impact recommends 80°C as the maximum temperature.
Storage & Shelf Life Stored somewhere cool, dark, and dry, Tetrahexyldecyl Ascorbate should last 3 years.
Tips, Tricks, and Quirks According to Sandream Impact, “THDA [Tetrahexyldecyl Ascorbate] is approved as a quasi-drug in Korea at 2%, and in Japan at 3%.”
Recommended starter amount 30g (1.06oz)
Where to Buy it  Buy it from an online DIY ingredient supplier; mine was a gift from Simply Ingredients.

Some Formulations that Use Tetrahexyldecyl Ascorbate

Ascorbic acid (vitamin C)

What is it? Ascorbic acid is also known as vitamin C; it’s a potent antioxidant with fabulous brightening + collagen-boosting skincare benefits.
INCI Ascorbic acid
Appearance Crystalline white powder; much like table salt or sugar.
Usage rate 3–25% (source)
pH 2.2–2.5 (5% solution in water) (source)
Solubility Water soluble
Why do we use it in formulations? Vitamin C helps increase collagen production, reduce excess pigment/brighten the complexion, boost healing, and counter UV damage. It’s an amazing, well-studied skincare active. Learn more about it with this great post from LabMuffin!
Do you need it? No, but if you’re interested in formulating high-performance skincare products it’s definitely something to consider.
Refined or unrefined? Pure ascorbic acid only exists as a refined ingredient.
Strengths Ascorbic acid is a well studied, highly effective skincare active. It’s also pretty inexpensive!
Weaknesses Ascorbic acid is very unstable in water, breaking down in less than a month.

Ascorbic acid can also be irritating to the skin, with higher concentrations having a higher irritation potential. More isn’t necessarily better; start with a lower concentration and work your way up if desired/required.

Alternatives & Substitutions Vitamin C derivatives like Tetrahexyldecyl Ascorbate, Ascorbyl Palmitate, magnesium ascorbyl phosphate, sodium ascorbyl phosphate, and L-ascorbyl palmitate can be good alternatives. These derivatives can be oil or water soluble, so make sure the solubility is compatible with your formulation. These derivatives are typically more stable than ascorbic acid and less irritating, but they’re generally not as effective and they’re usually more expensive ($7/oz vs $20/oz).

You can also look at using other ingredients that also offer similar skincare benefits (you may want to blend two or three ingredients). Niacinamide (Vitamin B3) would be my top choice as it has both skin-brightening and collagen-boosting effects. N-Acetyl Glucosamine (NAG) also offer skin-brightening benefits. Vitamin E is a great antioxidant.

How to Work with It When formulating with ascorbic acid and water you’ll need to include ingredients that stabilize it and/or plan to use it within a week or two. For a formulation including stabilizers, check out this Skinceuticals-Dupe Vitamin C serum from The Acid Queen. For an easier, use-it-up fast formulation, Lab Muffin has shared a 5-minute DIY Vitamin C Serum formulation.

As ascorbic acid is very acidic you’ll need to raise the pH of your formulation to around 3.5 using something basic; a 10% sodium hydroxide solution works well for this job.

You can also use ascorbic acid in anhydrous formulations, like ones sold by The Ordinary and Paula’s Choice. Since ascorbic acid won’t dissolve in an anhydrous base you’ll want to use a finely powdered version for a smooth finished product; you can purchase extra-fine versions or use a coffee grinder/mortar & pestle.

Storage & Shelf Life Lotion Crafter recommends purchasing ascorbic acid in amounts you can use up in 3–4 months. Learn more here.
Tips, Tricks, and Quirks Don’t use ascorbic acid products with copper ions or benzoyl peroxide as those ingredients will deactivate the vitamin C (source: LabMuffin).
Recommended starter amount 30g (1.06oz)
Where to Buy it Buy it from an online DIY ingredient supplier or Amazon. This is an ingredient that you can purchase as a supplement, just be sure to choose a pure powdered version rather than pressed tablets (those will have some other ingredients in them to bind the tablet together). The powdered L-ascorbic acid that The Ordinary sells will also work, and is reasonably priced for a small amount.

Some Formulations that Use Ascorbic Acid

Tocopherol (Vitamin E)

What is it? Vitamin E is a potent antioxidant and beneficial skincare ingredient, helping protect the skin from environmental damage. It’s a naturally occurring vitamin that can be found in many carrier oils, like argan oil and cherry kernel oil, but when we talk about adding vitamin E to our formulations, it is a refined and concentrated ingredient.

The term “vitamin E” refers to 8 different chemical compounds: four tocopherols and four tocotrienols (alpha, beta, gamma, and delta). Different vitamin E products can contain different blends or isolations of these different vitamin E chemicals. Those different blends can mean the product is better suited to certain uses than others, and can also impact the price. I recommend this very thorough article from Skin Chakra to learn more. The Wikipedia article on tocopherol is also very helpful.

It is important to know that vitamin E is not a preservative. While it can help extend the shelf life of our products by delaying the onset of rancidity, it does nothing to prevent microbial growth.

I use Vitamin E MT-50 Full Spectrum in my formulations. This product is composed of 50% tocopherols (d-alpha, d-beta, d-gamma, and d-delta) in a base of GMO-free soybean oil. You could use Vitamin E USP instead, but it is typically more expensive. I don’t recommend using vitamin E capsules or oils that are designed for direct application to the skin as these are not cosmetic ingredients, but cosmetic products.

INCI Tocopherol
Appearance Viscous amber liquid
Usage rate I typically use vitamin E at 0.5% of the oil phase to delay oxidization. New Directions Aromatics recommends 2–30% for skincare benefits.
Texture Sticky, thick
Scent Oily
Approximate Melting Point The 50% vitamin E I have is a thick liquid at room temperature; the more concentrated the product is, the thicker it will be.
Solubility Vitamin E is oil soluble.
Why do we use it in formulations? When you see vitamin E used at low concentrations (≤0.5%), it is there as an antioxidant, acting to delay the onset of rancidity. At concentrations of 2% and more, it will be contributing skin benefits as well as antioxidant benefits to the formula.
Do you need it? Yes.
Refined or unrefined? Vitamin E only exists as a refined product.
Strengths Vitamin E is an excellent, readily available antioxidant that also has skincare benefits.
Weaknesses It can be a bit pricy, but a little goes a long way!
Alternatives & Substitutions Look for other oil-soluble antioxidants; rosemary seed extract is a common one, though it is more expensive.

Vitamin E acetate is not a great alternative for tocopherol if you are including vitamin E in a formulation as an antioxidant (source). Vitamin E acetate can sub in for skin benefits, but not as an antioxidant.

How to Work with It Include tocopherol in the cool-down phase of your formulations.
Storage & Shelf Life Stored somewhere cool, dark, and dry, vitamin E should last 12 months. I don’t recommend purchasing vitamin E in bulk; at 0.5% you likely won’t use much over the course of 12 months!
Tips, Tricks, and Quirks Learn more about vitamin E with this great blog post from Realize Beauty! This awesome post includes a de-bunking of the myth that excess vitamin E becomes a “pro-oxidant”.
Recommended starter amount 30g (1.06oz)
Where to Buy it Buy it from an online DIY ingredient supplier or Amazon. I don’t recommend using dietary capsules, though if you really want to please research exactly what is in the capsules you want to use so you understand what you’ve got.

Some Formulations that Use Vitamin E

Niacinamide (Vitamin B3)

What is it? Niacinamide is “an amide derivative of nicotinic acid“, also known as Vitamin B3.
INCI Niacinamide
Appearance White powder
Usage rate Niacinamide is typically used in the 2–6% range, though I’ve seen recommendations as low as 0.05% and as high as 10%.
Scent Nothing much
Solubility Water
Why do we use it in formulations? Niacinamide is a fantastic skin care active! It helps down regulate sebum production, reduce inflammation, decrease acne lesions, increase the synthesis of ceramides, reduce transepidermal water loss (TEWL), reduce fine lines, fade age spots and hyperpigmentation, and brighten the complexion.
Do you need it? No, though if you are interested in skincare I recommend it.
Strengths Highly effective, well-researched skin care active with many benefits.
Weaknesses While it is usually well tolerated, it can be irritating to some.
Alternatives & Substitutions Nothing is a complete substitution; you may need to combine multiple ingredients to replace all the jobs niacinamide (Vitamin B3) performs in our formulations.

Panthenol (vitamin B5) plays some of the same roles and can be a decent alternative. N-Acetyl Glucosamine (NAG) is also worth trying.

You could try choosing a botanical extract that has comparable properties depending on what you are trying to achieve. A humectant or hydrolyzed protein could also be a decent choice.

You will have to do your own research and testing if you wish to substitute niacinamide (Vitamin B3).

How to Work with It Include it in the water phase of recipes; supplier formulations indicate it is a-ok to include in the heated water phase.

I’ve found varying recommendations for the final pH of the product. The recommended final pH is typically around 5–6, but Amanda at Realize Beauty and Stephen at Kind Stephen have articles on on how and why a lower final pH is also likely to be ok. There’s also some interesting discussion on Chemists Corner (1, 2, 3) that draws the same conclusions. Based on the conclusions of professional cosmetic chemists, I generally aim for 4–6.

Storage & Shelf Life Stored somewhere cool, dark, and dry, niacinamide should be shelf stable for up to three years.
Tips, Tricks, and Quirks If you want to try niacinamide in your skin care routine before investing in the raw ingredient I would highly recommend The Ordinary’s 10% Niacinamide + 1% Zinc formulation. It has absolutely revolutionized my skin and it’s under $6!

If your primary aim is brightening, a combination of niacinamide (Vitamin B3) and N-Acetyl Glucosamine has been shown to be more effective than niacinamide (Vitamin B3) alone (source).

La Roche Posay (a well-respected skincare brand) uses niacinamide (Vitamin B3), glycolic acid, and salicylic acid together in their Effaclar Ultra Concentrated Serum, which would have a pH around 3.6–3.8 as that is the pKa of glycolic acid. I’ve used this serum for months without any irritation.

Recommended starter amount 10–30g (0.35–1oz)
Where to Buy it  Buy it from an online DIY ingredient supplier.

Some Formulations that Use Niacinamide

Panthenol (Vitamin B5)

What is it? Panthenol (vitamin B5) is a vitamin that is fantastic for skin and hair care. D-panthenol (dextrorotatory panthenol) is metabolized into D-pantothenic acid by the body, and that’s the type of panthenol that works wonders in our formulations.
INCI Panthenol
Appearance You can purchase it as a white crystalline powder or a clear liquid.
Usage rate 1–5% in skin care, with the higher end of the range for more therapeutic applications.

0.75–1% for shampoos and conditioners, 0.5–0.75% for hair styling products. 1% for nail care.

Scent None
pH 8–9
Solubility Water
Why do we use it in formulations? Panthenol acts as a moisturizer by drawing water from deeper layers of the skin into the upper layers of the skin. It helps with softness and elasticity, and is anti-inflammatory. It stimulates skin re-generation and boosts healing.

In hair care it is a small enough molecule to penetrate the hair and moisturize it, helping increase elasticity/reduce breakage. It makes hair softer and shinier, and reduces static.

Do you need it? I highly recommend it.
Strengths Panthenol is an insanely versatile skin and hair care ingredient with a proven track record of awesomeness.
Weaknesses I can’t really think of anything. There’s been a shortage lately so it’s more expensive than it was in 2017, but given the low effective usage rates it is still a very cost effective ingredient.
Alternatives & Substitutions N-acetyl glucosamine, allantoin, and urea share some similarities with panthenol. You can attempt to replace some of the humectant properties with ingredients like a hydrolyzed protein or a humectant, and some of the skin soothing benefits with an herbal extract like calendula.
How to Work with It Include the powdered version in your heated water phase; the liquid version is heat sensitive so it should go in the cool down phase. Both versions can be cold-processed in products that don’t require heat.

If a formulation calls for powdered panthenol and yours is liquid, you’ll need to make some slight modifications as the liquid version is less concentrated than the powdered version. The first thing you’ll need to do is determine the strength of your solution; this is a piece of information your supplier should provide. From what I’ve seen, liquid panthenol products are usually a 50% solution. That means that in order to get the same amount of panthenol, you’ll need to use twice as much, and reduce the amount of water in the formulation to make room for it. So, if a formulation called for 2% powdered panthenol you’d need to use 4% liquid panthenol, and reduce the water in the formulation by 2%.

Storage & Shelf Life Stored somewhere cool, dark, and dry, panthenol should last two years.
Tips, Tricks, and Quirks The “Pro-V” in Pantene is panthenol! V = 5 in Roman numerals.
Recommended starter amount 30g (1oz)
Where to Buy it  Buy it from an online DIY ingredient supplier or Amazon.

Some Formulations that Use Panthenol