In the following, everyone who wants to produce their own cosmetics should be given the necessary basic knowledge to be able to try out their own individually designed recipes. The prerequisite for this is a profound knowledge of basic and auxiliary materials, emulsifiers as well as additives and active substances. At the beginning, everyone has to think about the individual components of their recipe. These are derived from the desired effect on the skin. Therefore, one starts by answering the questions:
What effect should be achieved by the product?
For which skin condition or purpose should the product be suitable?
From the basic recipe to packaging of the final product, the required individual components are described in more detail below.
As described above, the emulsion system will usually consist of an oil and water phase. It is best to use a simple basic formulation, which can then be adapted as required. By exchanging the oil phase or the emulsifier, new formulations can be successfully created. The ratio between emulsifier and oil or water phase should be maintained though.
Water phase: For the water phase, either a herbal destillate or water in distilled or demineralised form should be used. Normal tap water usually has a too high lime content and the ions in the water can negatively influence the properties of the concoction.
Oil phase: For the oil phase oils, liquid grease or waxes are required. For the application on the skin natural vegetable oils and waxes should be used.
Emulsifier: Depending on the desired end product (O/W or W/O emulsion) a suitable emulsifier is selected. The emulsifier determines the phase distribution of the end product:
Based on the desired effect on the skin, different active substances are selected. Not too many substances should be chosen at once (max. 5) because the more ingredients are added the higher the probability of incompatibilities. If one still wants to benefit from a high number of active substances, it is possible to divide them into different creams (day cream, night cream, eye cream etc.).Active substances for different skin types
Active substances in cosmetics
Additives are used to improve the smell, color or application properties of the product. As the name suggests, they are not always absolutely necessary.
Smell: For a pleasant smell of the product it is best to use essential oils. Only a few drops should be used, as the smell can quickly become obtrusive. To test the compatibility of the fragrance, an application test should be carried out on the skin.
Color: Food colors and vegetable color pigments can be used as coloring agents in cosmetics. In order to avoid allergic reactions, one can limit oneself to the skin-compatible vitamin carotene oil, which is an active substance as well as an orange-red dye.
pH-Regulators, puffers: Some substances only work optimally in certain pH ranges (e.g. preservatives), so it may be necessary to adjust the product to a certain pH value. For this purpose, the pH value of the created product is measured with a pH paper. Then a citric acid solution or lactic acid is added drop by drop and the pH value is measured again and again until it reaches about 5.5 (pH value of the skin).
Spreading agents: Spreading agents improve the spreadability of preparations. This is particularly advantageous for body lotions or sunscreens. In case of eye creams this should of course be avoided so that the product does not get into the eyes. Spreading agents belong to the group of liquid lipids and are therefore mixed with the other lipids in 2-phase systems.
Antioxidants and preservatives: Antioxidants are used to stabilize oils, fats and waxes that are sensitive to oxidation. Preservatives are used to protect against microbial decay of products containing water.
In order to ensure an acceptable period of application of the created product, additives may be required to improve the microbiological and chemical stability.
Microbiological stability: Recipes with water can only be kept in the refrigerator for a few days, as bacteria or fungal strains can grow. To counteract this process, preservatives approved for natural cosmetics can be used. Alternatively or additionally, mono- and polyvalent, short-chain alcohols can be used. Alternatively, antimicrobial and disinfectant agents (e.g. thyme oil or clove oil) can be used, although there are no reliable values of the type of stabilisation available for these.
Chemical stability: Chemically, ingredients are mainly changed by oxygen, but also by light and heat. This causes the product to turn rancid and free radicals harmful to health are formed. This process can easily be counteracted by adding antioxidants (vitamin E). The product should additionally be stored in a dark and cool place.
After you have gathered the ingredients of your recipe, they must now be processed. It is advisable to sort the ingredients and group all the ingredients belonging to the oil phase (fat soluble), as well as the ingredients of the water phases and the thermo-unstable ingredients that are added last.
Oily solutions do not contain a water phase and therefore there will be no contamination. However, antioxidants should be added to oils to avoid rancidity.
Gels used for cosmetic purposes are mostly hydrogels (water-based) and therefore preservation must be taken into account.
To obtain more solid lipophilic products, you need sufficient solid lipids, which are melted to mix with other ingredients. There is no water in this preparation and therefore there is no need for preservation. However, attention should be paid to the addition of antioxidants.
Emulsions are a mixture of two phases, the water and the lipid phase. The ingredients are divided into lipophilic ingredients and lipids, hydrophilic ingredients and water, emulsifiers and thermo-unstable ingredients. As both water and oil are present, it is necessary to preserve and pay attention to the addition of antioxidants.
The filling vessel should protect the concotion from light and air. It should be cleaned and disinfected before filling. The advantages and disadvantages of the various packaging options are listed below.
Synthetic material / Plastic: Plastic containers are porous compared to glass and allow oxygen to pass through. Oxidation can cause the contained preparation to lose its effect.
White glass: The advantage of white glass is that the color of the cream is always visible and suspicious color changes are easily noticed. However, white glass does not protect the preparation from light and should therefore be stored in light-protected drawers or cupboards.
Brown glass: Brown glass is the more cost-effective alternative to violet glass. It offers moderate protection against light and can therefore extend the durability of the contained product.
Violet glass: This type of glass is probably the most suitable type of dispensing container for cosmetics. It is capable of rejecting visible light frequencies (blue, green, yellow, red) while allowing ultraviolet, violet and infrared light to enter the glass. According to the findings of bophotine research ultraviolet and violet light has virus and bacteria killing effects as well as a cell regenerating effects.
Elsässer, S. (2008). Körperpflegekunde und Kosmetik: Ein Lehrbuch für die PTA-Ausbildung und die Beratung in der Apothekenpraxis (1. Aufl.). Berlin, Germany: Springer-Verlag.