Petroleum jelly, an ingredient with unique qualities

Known for over 100 years, petroleum jelly occupies an enormous space in the range of pharmaceutical and cosmetic ingredients. Its chemical nature and colloidal microstructure define its multiple qualities as well as its uses, such as:

Neutral excipient

In the same way as water is used as an inert vehicle for hydrophilic active substances in skin allergy tests (patch), petroleum jelly is commonly used to vehicle lipophilic active substances for many applications.

Inertia being one of the most sought qualities for excipients, they must be as neutral as possible with regard to fragile active ingredients like hormones, vitamins, antibiotics, perfumes, colourings, etc. It is fundamental to note that an excipient, also known as a “vehicle” or an “adjuvant”, can significantly modify the activity of an active ingredient and the shelf life of the formulation; it is therefore often necessary to repeat clinical trials after changing an excipient. Petroleum jelly is inert, and thus totally compatible, whatever the active substance used. Petroleum jelly-based ointments are recognised as the best releasing systems in terms of efficiency. For example, the efficiency of topical steroids can be increased by the application of an occlusive film created by an ointment. In fact, skin under occlusion becomes more permeable and the active ingredients are able to penetrate better.

A little chemistry…

From a chemical point of view, petroleum jelly is a purified mixture of long-chained saturated hydrocarbons (also known as alkanes or paraffin), solids and liquids of general formula (CnH2n+2). They are mainly obtained from refining petrol. Our first lessons of organic chemistry taught us the designation “paraffin” from the Latin “parum affinis”, signifying “little affinity”, with reference to their low reactivity. This chemical and physiological inertness makes petroleum jelly an ideal vehicle for protecting delicate active ingredients, for creating ointments for sensitive skin, or for formulating products with an acid or alkaline PH (such as depilatory creams, hair dyes, creams with high doses of alpha hydroxyl acids for dermatological treatments)


Structuring agent, consistency factor
Due to its semi-solid consistency, petroleum jelly can be used as an ideal structuring agent for hydrophobic ointments. The microstructure of the petroleum jelly is an amorphous colloidal gel in which the continuous phase is made up from solid wax containing oil in dispersion. The wax absorbs oil just as gelatine absorbs water. Because of this capacity, petroleum jelly can also function as an anti-exudation agent for oil by replacing ceresin or ozokerite. This plastic and semi-solid structure grants petroleum jellies their pasty consistency, their smoothness, their delicate fibrous texture and their lubricating characteristics.

According to its specifications such as fibre length, viscosity, drop melting point or its capacity to absorb oil, petroleum jelly can be used as a regulator of consistence or a stabiliser for emulsions..

Active ingredient: protection, healing, moisturising
Pure petroleum jelly is sold by pharmacies for treating cuts, burns, rashes, damaged feet, cracked lips, babies’ nappy rash and protection against cold. The main function of all these treatments is to cover and protect the skin from thermal, bacterial and chemical aggressions. Petroleum jelly is impermeable to air and water; its capacity for protecting cuts and burns prevents germs from entering the wound and keeps the wound soft by preventing the evaporation of humidity.

A skin protection screen

Some examples: the greasy gauze bands applied to burns; the petroleum jelly creates a moist environment favourable to healing. In contact sports such as boxing, it is applied to limit bleeding, protect cuts and limit the apparition or enlargement of cuts. Swimmers smear their bodies with petroleum jelly to reduce the effects of cold temperatures. Due to its characteristics, it is often found in cosmetic creams for protecting hands and feet. In short, it functions as a screen, protecting the skin from exterior aggressions and enabling self-healing in the case of wounds.


Moisturising characteristics
By reducing the trans-epidermal water loss by more than 98%, petroleum jelly is an excellent occlusive moisturiser of reference. It creates an inert hydrophobic barrier on the surface of the skin, blocks the trans-epidermal water loss and traps the water under the skin.

Due to its excellent moisturising powers, many dermatologists use petroleum jelly for treating problem skins such as dryness or squalms. Petroleum jelly accelerates the recovery of the normal properties of the skin barrier, in the case of injured skin. This is its purpose in the composition of creams prescribed for dry skin, psoriasis, atopic dermatitis, hyperkeratosis and xeroderma…


Emollient
Due to its softening ability, petroleum jelly is the ultimate emollient; its non-sensitising and highly occlusive properties are effective against trans-epidermal water loss. Its role is to remain on the exterior of the skin: therefore it is very useful in cosmetic protection creams, make-up, sun care and ethnic hair care products.

Petroleum jellies can, for example, be chosen for their stringiness (capacity of the product to stretch into fibres more or less long). The choice of the fibres depends on its use: for a massage cream or for brilliantine, short fibred petroleum jellies are preferred since they are less sticky and melt easily.

Lubricant
Due to its excellent lubricating properties, petroleum jelly is also used in athletics care. Boxers apply it to soften the skin and thus prevent it creasing and tearing from hits.
Its greasy consistency makes the punches “slide”. Rugby men use it for the same reason, but also, to protect their ears and faces from friction in the scrums. Its excellent “sliding” factor facilitates all kinds of massages. Contrary to popular belief, it is not advisable to use it as a gynaecological lubricant with condoms as it is not compatible with latex.