Emulsions - creams, lotions

Emulsions - creams, lotions

What is an emulsion?

An emulsion is a stable mixture of water and oil. Because water and oils are not miscible, an agent is needed to ensure that the water molecules bind to the oil molecules. Because preparations containing water are sensitive to microbial contamination, the use of a preservative is mandatory. 

Certain compositions can be prepared that do not require an emulsifier, where the oily part encloses the water but is not chemically bound to it. There are also certain gels where the gel structure incorporates the oils, practically disperses them evenly, and no emulsifier is needed.

Hot emulsification is a chemical, mechanical and thermal process at the same time.

Which cosmetics can be prepared by emulsification?

  • skin and body care creams
  • cleansing or tonic lotions
  • body lotions, body milk
  • sun protection lotions and creams
  • hand and foot creams
  • body butters (which also contain water)
  • cream shampoos, hair conditioners
  • makeup: foundation, mascara

The components of an emulsion are as follows:

OILY PHASE consisting of oils, oily macerates, vegetable butters, lanolin, heat-insensitive lipophilic ingredients

EMULSIFIER and possibly one or more co-emulsifiers, wax

AQUEOUS PHASE which can be formed from a choice of plain mineral water, distilled water or floral water, glycerin, hydroglycerin extracts, thermally insensitive hydrophilic ingredients

FINAL PHASE (cooling phase) contains active ingredients (hyaluronic acid, coenzyme Q10, vitamins ...), heat sensitive ingredients, extracts and fragrance essences, essential oils, acidity correctors, preservative

Standard procedure for preparing hot emulsions:

  • PREPARATIONS: disinfect the worktop, prepare the ingredients given in the recipe, disinfected the utensils as well as the dedicated container
  • although gram measurement of ingredients is the most recommended and accurate, they can also be measured volumetrically. Our recipes generally give both options. It is recommended to use heat-resistant glasses for phase heating, for example Berzelius beakers. If you do not have a scale, you will need a few cylinders or other graduated vessels, syringes and pipettes, measuring spoons. You will need paper towels, a stainless steel pan for the water baths; a heat source should be at hand.
  • MEASUREMENTS: measure the ingredients for the oily phase and transfer them to a heat-resistant glass. In another heat-resistant beaker measure and transfer the ingredients for the aqueous phase.
  • HEATING: both phases are put in a water bath and the heating starts. The contents of the phases are mixed from time to time. After a while, the glasses may start to move around in the pan, in which case the intensity of the heat source is reduced. If the recipe does not state the temperature to which the phases must be heated, then they are kept warm until the oily phase is completely melted. The suitable temperature for emulsification is generally 70° Celsius.
  • EMULSIFICATION: the contents of the two phases must have the same temperature. Remove from the heat. Usually the aqueous phase is added over the oily phase, but the recipe may indicate the opposite, depending on the emulsifier used. Combine phases. The process takes an average of 3 minutes. To accelerate the cooling process, place the composition over a bowl with cold water and continue to mix either with the mixer or with a whisk or a teaspoon, depending on the consistency of the preparation. Stir for approximately 3 more minutes. The composition, depending on the ingredients and emulsifier, may still be quite liquid, but will thicken after cooling to body temperature. Some emulsions reach their final consistency in 24 hours.
  • COOLING PHASE: the next step is the incorporation of the final phase ingredients: active ingredients, vitamins, essential oils, lactic acid, extracts, preservatives. These ingredients are added one at a time, mixing after each. Homogenization must be done thoroughly until the composition has cooled (and solidified as appropriate). Insist on dispersing the preservative as evenly as possible.
  • READY: the composition is transferred to the dedicated container , using a teaspoon, funnel or syringe. The container is labeled with the name and possibly the ingredients, with the date of preparation and the expiration date. In most cases, it is not advisable to transfer the composition to the container as long as it is warmer than the ambient temperature.

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On our website you have a series of recipes formulated and presented in detail, but if you want to customize or replace certain ingredients, we suggest you follow the instructions found in the article about recipe adaptation.

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Depending on the basic ingredients chosen, and the emulsifier used, emulsions with various textures and with different sensations and effects on the skin can be obtained:

TEXTURES: fluid, milky, gel type, aerated foams, smooth, fine, consistent, unctuous

FEELING ON THE SKIN: fresh, slippery, refreshing, enveloping, silky

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FAILURE OF EMULSIONS

The failure of an emulsion can be evident immediately after emulsification or even during the process. It can become visible during the incorporation of the ingredients in the cooling phase or after preservation, or it can be evident in 2-3 days after preparation. a) the emulsion can become like a broken mayonnaise (or like curdled milk) during emulsification, immediately after emulsification or when incorporating the final phase ingredients b) the emulsification is not produced, when mixing the oily phase with the aqueous phase a liquid solution is formed, which does not acquire the right consistency during mixing and cooling, and in a short time the ingredients separate c) the emulsion can separate in a few hours, the next day (most likely) or in the following days after preparation. In these cases the emulsion cannot be saved. An irreversible rupture of the interfacial surface between the phases occurred. The cream is not what it should be, it can eventually be applied to the body in the form of a massage (using it generously) within 1-2 days, so as not to be a total loss. Failure can become a lesson learned.

  • the obvious aspect of a broken emulsion is the curdling and precipitation of some ingredients, or the visible separation of the phases
  • the main signs of emulsion destabilization over time are the fusion of oil molecules, sedimentation, floating of a liquid on the surface of the composition, a visible layer of water at the base of the composition

The main causes that determine the failure of hot-prepared emulsions:

  1. the emulsifier is chosen incorrectly in accordance with the dosage and phase ratio
  2. insufficient amount of emulsifier
  3. adding the emulsifier in the wrong phase
  4. low temperature or a temperature difference between phases at the time of emulsification
  5. reverse phase combination
  6. inadequate mixing - too slow or short. Generally, the mixing should take 3 + 3 minutes. The ingredients from the final phase are added progressively, the composition is mixed well after each one
  7. incorporation of incompatible ingredients, in particular the use of an inappropriate preservative
  8. the final phase is too busy, too many ingredients are used or in a large quantity

. . . Failure of cold creams It is difficult to make such an emulsion without the aid of an emulsifier. Creams made from oil, water and wax are difficult to prepare. The procedure requires patience, thorough mixing and drop by drop water dosing. In our recipes you can find cold creams prepared with the help of emulsifiers or co-emulsifiers.

Conclusions:

  • consider spoiling an emulsion as a useful experience
  • spoilage of the same emulsion several times requires a closer analysis of the ingredients and process
  • try to identify what went wrong by immediately noting your findings and suspicions
  • where did it go wrong at dosing? did you read the instructions from the emulsifier product sheet? did you not measure the temperature? did you rush into mixing? is the preservative incompatible with any ingredient? is the final phase too busy?
  • reevaluate the formula and procedure
  • prepare a small test amount, especially if you have reformulated a published recipe or formulated a new recipe

Happy formulating!

 

Video presentation with the preparation of a cream by hot emulsification

 

Video presentation with the preparation of a cold emulsification cream

This formula was developed by Elemental's qualified staff. The recipes are intended to exemplify the use of products marketed by Elemental and are believed to be accurate, however, Elemental assumes no liability or risk associated with the use of its products for the preparation and evaluation of the recipe as the conditions of preparation and use are beyond its control. The Elemental customer must ensure that the reproduction of the formulation does not infringe any intellectual property rights and that it complies with the specific rules and regulations in force. The person who prepares the recipe must refer to the safety data sheets to ensure the safe handling of all raw materials and bears full responsibility for ensuring the safe and correct use and storage of all materials procured and used. Assessments of the safety, stability, regulatory compliance and suitability of this recipe, methods and the finished product are the sole responsibility of the user and/or the legal entity placing the product on the market. Elemental is not liable for any damages resulting from the use of this information, and assumes no responsibility for misuse of selected materials, formula or method, in whole or in part.

Posted on 07/20/2015 Tutorials

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