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Oleaginous constituents

These are effectively oils, (vegetable or mineral), or other substances that will freely mix with oils, such as waxes, fats, greases, and volatile oils. When they are mixed with aqueous constituents to form an emulsion, they are known collectively as the oleaginous phase (or oily phase). However, when we are discussing creams and the like we often talk about ‘oil’ as a sort of shorthand to include all the oleaginous constituents present.

Aqueous constituents

This refers to water or anything that is dissolved in water or can mix with it – there’s quite a list, including infusions & decoctions, alcohol and ethanolic extracts such as tinctures, vinegars, glycerine, and honey. When making an emulsion such as a cream, these are known collectively as the aqueous phase. Once again, we may be lazy and just refer to the whole lot as ‘water’.

Emulsifiers

Emulsifiers (aka emulgents or emulsifying agents) must be present in creams and other emulsions in order for a stable mixture of oleaginous and aqueous constituents to be formed. Strictly speaking oil and water never actually mix together – the effect of emulsification is to cause, for instance, the oily ‘phase’ to break down into very tiny droplets that are held in suspension in the aqueous phase, (or it could be the other way round). Very ‘runny’ emulsions are usually temporary in nature (as observed when dairy cream separates from milk) but they will recombine when shaken together. In the case of a cream, some of the constituents (usually the oily ones) will set hard at room temperature, forming a stable, semi-solid product. Emulsifiers occur naturally, albeit often in very small quantities, in useful substances such as beeswax and unsaturated vegetable oils. However, much greater versatility is possible if you use a commercial emulsifying agent such as Emulsifying Wax BP, or it’s more natural predecessor, Lanette Wax.

Formulation of creams is primarily about bringing therapeutic substances in contact with the skin, but one also has to weigh up other factors: –

  • Very oily creams will tend to be occlusive, tenacious and moisturising. Conversely very watery creams will tend to be drying, well absorbed, and are soon gone.
  • It’s often advantageous to include constituents that help to make a cream more ‘sticky’, so it will spread over and adhere to the skin better. Alas, the oh-so-useful lanoline is a thing of the past, but we still have things like glycerine and soft paraffin to perform this role.
  • Because creams contain water, they are vulnerable to infection. It helps if the product and its container start their working lives sterile – but in use, exposure to the air and microbes transferred from fingers will soon cause a cream to go off… unless a preservative is used. Including essential oils for this purpose is often disappointing – they’re mostly tucked away in the oily phase, so they have very little preservative effect on the water-based constituents. Further, in order to achieve an adequate preservative (antimicrobial) effect the essential oil content of your cream would need to be at least 4%. At this level it will probably affect the emulsifying properties of the cream, and will almost certainly irritate the skin. So usually it’s necessary to use a commercial preservative if you want your creams to last more than a week or two.

 

WATER IN OIL CREAMS

The first sort of cream to attempt, water in oil creams are useful to practice and perfect as they are made from such simple ingredients. The two stage process is important, keeping the aqueous and oleaginous phases separate until the latter is fully dissolved and they both have the same temperature – this makes it easier for the emulsifier to do its work.

Basic Cold Cream

Water in oil creams are often referred to as Cold Creams (a historic term from the days when the only comparison was ointments – creams feel more cooling on application).  Although they are seldom found in modern cosmetics, they are useful therapeutically. They are indeed more cooling and less greasy than an ointment and are more easily spread over the skin, useful for dry areas such as elbows, feet, hands, knees and legs. Because they leave a good occlusive barrier behind, they can be useful for conditions like nappy rash and haemorrhoids.

Beeswax pellets

5 – 10

g
VO Vegetable oil

60

ml
Water or infusion

40

ml
EO Essential oils

10-20

gutte

This is a general formula to make 100g. Try this to start with until you’ve got the knack, after which you may want to make larger quantities for convenience. Variations to consider are: –

  • You can substitute one of the ‘butters’ (Coconut, Cocoa or Shea) for some or all of the beeswax.
  • Vegetable oils might be plain Sunflower or Olive oils (cold-pressed will work best) or an infused oil such as Marigold or Comfrey.
  • The water could be an infusion… perhaps of the same herb as the infused oil.
  • Essential oils can be chosen to compliment the therapeutic activity of the cream. If in doubt, use Lavender!

As an example, you might use Marigold (Calendula officinalis) infused oil, an infusion of Marigold flowers, and Tea Tree essential oil).

First make a good, strong infusion of your chosen herb, filter it, and return the infusion to the pan, (or just warm up some plain water if you prefer). Whilst doing this, melt the beeswax in a double boiler or porringer, then stir in the infused oil until it’s all melted. Adjust the temperature to 70°C (using a thermometer). Warm the infusion again until it also reaches 70°C. Remove both from the heat and pour the infusion in a slow, steady stream into the melted beeswax/oil mix, whisking furiously all the time. Keep whisking as it cools down to make sure the water stays finely dispersed in the oil. When it starts to thicken, stir in your chosen essential oils, transfer to a jar and seal when fully cooled. This simple cold cream has no preservatives – keep it in the fridge, but still expect it might go off within 3 months.

You may get away without using a thermometer – 70°C is close to the point at which beeswax will melt, whilst in an aqueous infusion 70°C is a comfortable ‘sipping’ temperature. The important things is that both phases should be close to the same temperature, otherwise things will probably go wrong.

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