Conditioning Agents for Hair and Skin

Petrolatum: Conditioning Through Occlusion 69
Different "variations" of petrolatum can be obtained (higher or lower melting
points, different consistencies, etc.) by changing the formula of the wax
product which is to be purified, as shown in Figure 6. Another method of
preparing different petrolatums involves simply blending the final petrolatum
product with wax and/or oil. Since the petrolatum is already present as the base
material, additional wax or oil can be mixed without the aforementioned problems
of separation which are encountered when attempts are made to prepare
petrolatum from just oil and wax.
Of course, in every step along this lengthy production process, the refinery
operator can make adjustments which will vary the types and amounts of products
formed. Thus, the process is quite flexible and allows the maximum utilization
of crude oil while simultaneously providing maximum yield of the desired
petroleum products. Such an efficient process enables the refinery to
make multiple salable products with essentially no waste. Given the cost of
crude oil, it is not surprising that the petroleum refinery recycles the processing
material as much as possible and utilizes every drop of the crude oil.
VI. APPLICATIONS OF PETROLATUM
A. Skin Conditioning as a Cosmetic ingredient
Two key characteristics of many skin conditioning agents are that they eliminate
dry skin and maintain moist, healthy skin. Petrolatum is one ingredient
which has performed these roles superbly for decades. In fact, the first public
document which described the benefits of petrolatum on dry skin was probably
Chesebrough's 1872 patent (12), in which he cited its excellence for use on
chapped hands. The current literature overflows with evidence that petrolatum
acts on the skin to make it more moist, supple, and both visually and
physiologically appealing. Even newspapers and magazines tout the benefits
of spreading petrolatum onto dry skin, especially during the winter season
when the need for skin moisturizers is great due to a combination of low humidity,
indoor heat, and reduced fluid intake.
While some studies indicate possible pharmacological mechanisms involving
petrolatum and the skin, this material's excellent occlusivity is the primary
reason why it is used as a skin conditioner. Blank showed in 1952 that water
in the stratum corneum is a primary factor for supple, smooth, healthy-looking
skin (19); therefore, ingredients which are effective at keeping moisture in skin
(such as petrolatum) will undoubtedly be excellent skin conditioners.
1. General Information
This conviction is widely held throughout the cosmetic industry. Petrolatum is
known as an excellent moisturizer, and this "moisturization" (i.e., reduction
of transepidermal water loss, TEWL) of the skin by petrolatum arises from its