Water-soluble and oil-soluble ingredients in cosmetics formulating

Water-soluble and oil-soluble ingredients in cosmetics formulating

8.3.2023

In the making of cosmetic products, it is very important to understand the solubility of different ingredients. Difference of water-soluble and oil-soluble ingredients in cosmetics formulating is big. Converting a cosmetic formula to a recipe is always based on the principle of solubility. Therefore, as a cosmetics maker, you should know in which group each raw material belongs. Most people are familiar with the solubility of many ingredients. Oils are, of course, oil-soluble and, for example, water and hydrolats are water-soluble. In this article, I will explain the solubility issue in detail and tell you why it is so important.

Solubility – what does it mean?

A solution is a mixture in which substances, when combined, form a single phase. Such a phase remains uniform and stable even if it is left untouched for long period of time. One of the most well-known water-soluble substances is common table salt, the sodium chloride. If you mix salt with water, it dissolves and becomes one phase with the water. In chemistry, solubility is equal to the ability of a substance to form a solution with another substance.

However, salt cannot be mixed with water unlimitedly. The mixture of salt and water can be saturated by adding the maximum amount of salt to the water. The amount of solubility of a substance in a certain solvent is usually measured as the maximum concentration of the dissolved substance in a saturated solution. You can try making a saturated solution of salt and water yourself. When the maximum amount is exceeded, the salt no longer dissolves in the water but remains at the bottom of the container. Now you have a saturated saline solution.

Water-soluble and oil-soluble do not like each other

It is important to know how to distinguish between water-soluble and oil-soluble ingredients in cosmetics formulating. Water-soluble (hydrophilic) and oil-soluble (lipophilic) ingredients are quite different from each other. Difference of water-soluble and oil-soluble ingredients in cosmetics formulating are like night and day. The easiest way to make a cosmetic product is to use only water-soluble ingredients or only oil-soluble ingredients in the product.

When making homemade cosmetics, you usually start by making simple water-free creams, balms and body butters. Anhydrous products are made only from oil-soluble ingredients. All vegetable oils, waxes and vegetable butters belong to this group. They are completely lipophilic ingredients.

If you add a little hydrolate to your water-free cream, it will instantly separate from the fat-soluble ingredients into its own phase. The hydrolate never forms a solution with oils. If you want to combine hydrolate, oils, waxes and vegetable butter, you need to make an emulsion using an emulsifier.

Facial lotions are also easy to prepare for beginners. Hydrolats, herbal decoctions and water are usually used for lotions. If you want to add essential oils to your lotion, you will immediately face problems. Essential oils are oil soluble and do not dissolve in water or hydrolats. The essential oils you stay separate and rise to the surface of the lotion and come out of the bottle first. You should always remember to shake the bottle vigorously and long enough. By doing this, the essential oils mix more evenly with the water phase. Essential oils mix briefly with water, but they do not dissolve. If you want essential oils to dissolve in water, you need a separate solvent.

Which ingredients are oil soluble?

Naturally all vegetable butters, vegetable oils and waxes are oil soluble. All vegetable oils naturally contain a little water. The maximum allowed water content of oils is 0.2%. In reality, the water content of high-quality oils is significantly lower than this. All oil producers constantly monitor the water content of their products. The high water content makes the oil poorly storable and significantly reduces its quality. A water content of less than 0.2% does not affect the composition of oil-soluble products.

When making water-free cosmetics, we do not have to be content with for just oils and vegetable butters. Many active ingredients in cosmetics are in oil-soluble form. In this way, they can be used in water-free products. Next, I will introduce some of the more familiar oil-soluble ingredients that you can use in your waterless creams. These ingredients should not be used in water-based products unless you use an emulsifier, meaning you are making an emulsion cream.

Special oils

I very rarely use the term special oils. In this context, however, the name seems appropriate. For example, sea buckthorn oil or neem oil are very special oils that are used only a few drops in the product. These oils are so full of antioxidants and polyphenols that they cannot be used like some regular oil. With special oils, you get not only colour in your anhydrous product, but also a lot of plant power.

Essential oils

Essential oils are wildly popular and often misunderstood. They are not actual oils but solvents. However, they are oil-soluble substances that do not dissolve in water. Never add essential oils to your toner without a solvent. You can add a maximum of 0.5-1% of essential oils to the anhydrous cream. Also, essential oil can be added to the emulsion as it contains oil-soluble substances.

Essential oils contain more than just fragrance. They contain plenty of plant active ingredients. Get to know different essential oils and find the right products for your skin type.

Macerated oils or herbal oils

Macerated oils, or herbal oils, are a great way to get the healing effect of plants in water-free creams. You can add 5-30% herbal oil of your choice to the cream. Remember that herbal oils contain very powerful plant chemicals. They must be used very deliberately.

Vitamin E

Vitamin E is one of the most effective antioxidants. It’s almost an essential ingredient when you make waterless creams. Anhydrous creams usually do not need a preservative, but vitamin E should be added to them. Vitamin E prevents fats from oxidizing too quickly.

Retinol and carotenoids

Retinol acts as a storage form of vitamin A on the skin. Vitamin A is very important for skin regeneration. In cosmetics, retinol in particular is commonly used in products that slow down skin aging. Retinol is hard to find for homemade cosmetics needs. Instead, you can use oil extracts containing carotenoids such as carrot oil or sea buckthorn oil for homemade products. Carotenoids are precursors of retinol.

Squalane

Squalane is usually made from olives. It is the same substance as squalene, which occurs naturally in the skin. Squalane is a lipid,  fatty substance, which is also an antioxidant. Squalane also has skin-protecting properties. Squalane makes creams feel less greasy. For that reason alone, it should be included in cream recipes.

Ceramides

Ceramides are among the world’s most expensive cosmetic raw materials. Ceramides occur naturally in the skin. It is a lipid that is part of the sebum of the skin, whose task is to protect the skin. Ceramides are used in products intended for dry skin to protect the skin from epidermal moisture loss. It should only be added to creams in very small amounts.

Ascorbyl palmitate

Ascorbyl palmitate is often called oil-soluble vitamin C. However, ascorbyl palmitate is not vitamin C, the ascorbic acid, and it does not have the same effects as ascorbic acid. Ascorbyl palmitate is a very powerful antioxidant. However, it does not penetrate as deeply into the skin as genuine vitamin C, the ascorbic acid. The advantage of ascorbyl palmitate is its good shelf life. The light, time, heat and oxygen will not destroy it in the same way and as fast as natural, water-soluble vitamin C.

 

Which ingredients are water soluble?

The following ingredients are water soluble. These ingredients should not be used in anhydrous products. They do not dissolve in the oil but remain in the product as a granular or separate phase.

The most popular water-soluble ingredients in cosmetics are hydrolats and herbal decoctions and, of course, plain water. Use water-soluble active ingredients in your products when you make facial lotions and oil-free detergents. There are plenty of water-soluble active ingredients. You really have a lot to choose from. Here I have presented you just a few of the best water-soluble ingredients.

Vitamin C or ascorbic acid

Vitamin C is a particularly strong antioxidant. It has numerous positive effects on the skin. Vitamin C’s weakest feature is its shelf life. It does not last very long in products because it oxidizes very easily. I myself only make vitamin C serum for a few days’ needs at a time for this very reason.

Aloe Vera

Aloe Vera is perhaps the most famous herb used in skin care. Aloe Vera stores water in the gel-like structure of the leaves. This essence is used to make aloe vera products. You can get aloe vera in gel, juice or powder, from which you can make juice yourself. If you happen to have an aloe Vera plant at home, you can use the plant’s juice in your products. Aloe vera has many good properties. It contains a lot of salicylates, which belong to BHA fruit acids. Aloe Vera also contains a lot of saponins, which means it has skin and hair cleansing properties.

Glycerol

Glycerol is a water-soluble substance obtained from fats. All fats contain fatty acids and glycerol. Sometimes glycerol is used in very small amounts in water-free creams. Glycerol is a humectant. It attracts moisture and thus helps to keep the skin elastic. Glycerol is a very well tolerated ingredient. Many allergic persons use lotion containing water and 5-10% glycerol.

Herbal infusions

You can get plant power for products from various herbs by making herbal infusions from them. Herbal infusions are made like tea by infusing herbs in hot water. Feel free to try different herbs. You have plenty of herbs to choose from.

Alcohol extracts from herbs

Infusing wooden-like herbs and plant roots does not bring out active substances very effectively. I created an alcohol extract or tincture. Alcohol is not very good for the skin. Therefore, the tincture should only be used in very small amounts in products. A suitable amount could be 0.1-0.5%.

Allantoin

Allantoin dissolves in water to a limited extent. You can use it in products only in very small amounts. It is nevertheless a powerful ingredient. Allantoin is a skin moisturizing ingredient. It is made by synthesizing from synthetic uric and glycolic acid. Allantoin softens the skin and increases the water content of the cell’s external layer. You can also use allantoin in completely anhydrous products.

Niacinamide

Niacinamide is vitamin B3. It is an incredibly versatile active ingredient. You can use niacinamide for the skin’s protective layer and to fade uneven skin colour. Niacinamide also soothes reddened skin and reduces excessive sebum production.

Xanthan gum

Xanthan gum is a natural thickener in cosmetics. Xanthan is a food additive and therefore quite safe and well tolerated by the skin as well. Xanthan is suitable as a thickener for creams, lotions and gels.

Take advantage of insolubility

Sometimes it is quite appropriate to mix two insoluble substances together. As an example,  sugar peeling or salt peeling. Mix sugar or salt with oil. Sugar and salt are not oil soluble. That’s why they stay nicely granular in the oil. When you rub the sugar scrub on your damp skin, the sugar granules exfoliate comfortably. They melt quickly on damp skin and won’t scratch your skin. Such anhydrous products also keep well without preservatives, as long as you don’t touch the product with wet hands.

Two-phase products are a perfect example of how insolubility can be utilized in products. In a clear bottle, mix oil and hydrosol; you get a wonderful cleansing toner. However, always remember to shake the bottle well before use. If you do not do that, the oil will be floating on the surface of your toner.