70 JOURNAL OF COSMETIC SCIENCE
• European Union Guidelines -,,Data on composition between L+ lactic acid and other acids. Moreover,
and undesirable effects should be easily accessible to results of synergy studies are presented and the actual
the public -practical implementation of the Article BPD status of L+ lactic acid is discussed. To complete
7a(l)(h) of the Cosmetics Directive 76/768/WE" the picture, other important functionalities of L+ lactic
acid (e.g. descaling) in detergents are reviewed. L+
lactic acid is produced through fermentation of
L+ Lactic Acid: A BPD-Registered Anti-Microbial carbohydrates.
Ingredient For Acidic Cleaners
Robert Nolles
PURAC biochem bv
L+ lactic acid and lactates have been used for many
years in a wide variety of food products as a natural
preservative, because L+ lactic acid and lactates have a
proven functionality as a bacteriostatic agent. In this
respect L+ lactic acid gains more and more interest in
hygienic or disinfecting detergents formulations. In
addition, there is a clear trend towards more safe and
sustainable ingredients and detergents formulations.
Traditional biocides, on the other hand, are under
pressure due to toxicity issues, build-up of resistance
(e.g. Triclosan) and harm to waste water. This article
zooms in on the mechanism behind the anti-microbial
functionality of lactates and shows the difference
Formulating For Efficacy
Johann W. Wiechers 1 ,Caroline L. Kelly 2
,Trevor G.
Blease 2 ,J. Chris Dederen 3
1 Uniqema Skin R&D, Gouda, The Netherlands
2 Uniqema R&D Department, Redcar, United Kingdom
3 Uniqema Personal Care Applied Research, Meerbeek,
Belgium
Via the introduction of the Relative Polarity Index, the
authors show that the choice of emollients in cosmetic
formulations determines the total amount of skin
penetration of active ingredients whereas the choice of
the emulsifier determines its distribution within the
skin.

72
Introduction
JOURNAL OF COSMETIC SCIENCE
SrtUTEGIES AND TECHNl{JUES FOR TROUBLE-FREE
MANUFACTURING OF COSMETIC EMULSIONS
T. Joseph Lin, Ph.D.
628 Enchanted Way, Pacific Palisades, CA 90272
Faced with fierce competition and ever-changing market demands, cosmetic chemists are increasingly
under pressure to formulate large numbers of new products quickly. Frequently, insufficient time is
allowed for conducting stability tests and pilot batch experiments which are essential to assure sufficient
shelf life and trouble-free manufacturing operation. Among the various types of cosmetic preparations,
emulsion-based products, including suspensions, are most vulnerable to batch-to-batch variations in
product quality and stability. Such variations often result in QC rejection, causing time-consuming
reprocessing, inevitable delay in new product introduction or even expensive product recall. To reduce
processing costs, many manufacturers have increased batch size, and a batch failure can be very
expensive, not only in terms of the raw material cost but also the expense of disposi�g of the rejected bulk.
Clearly, the ability to ensure consistently uniform product quality in manufacturing a wide_range of
emulsion-based products is more important than ever for our industry.
Defining the Problem and Understanding the Causes
Key to developing a sound strategy for consistently producing trouble-free batches of diverse emuJsion
products is defining problems dearly and seeking to understand their true causes. Some problems, such
as pH value of a certain batch not meeting specifications, are usually not very difficult to define and the
extent of deviation from the norm can be measured objectively and accurately. Since there are only a
Jimited number of ingredients in the product which can contribute to the pH variation, isolating possible
variables and investigating the cause may not be very difficult.
However, there are other more complex problems involving certain visual characteristics such as
..product texture" which are more difficult to define and measure objectively. A sample of a cream from a
certain production batch may pass all measurable specifications such as pH, viscosity, specific gravity, and
yet its texture may appear different from that of the laboratory sample or previous batches. Whether this
variance should be sufficient to cause alarm may depend on the chemist's perception. An inexperienced
worker may ignore it whereas an experienced formulator may see it as a sign of something going wrong
with the batch and suggest further investigation. Ignoring signs of a potential problem can invite an
expensive product recall in the future. However, an error in identifying a non-problem as a problem can
also cause unnecessary delay in production -and resulting expense. Clearly, accurate definition and
evaluation of the problem is a very important first step in sohing the often complex problems involving
cosmetic emulsions.
Batch failure can result from many possible factors, and identifying the correct cause or causes requires
good understanding of the effects of key variables. Since consumer satisfaction is essential for cosmetic
products, any change in product properties that can affect consumers' perception of quality, safety, or
effectiveness needs to be controlled. For cosmetic emulsions these properties may incJude product
appearance incJuding color, opacity, and tex1ure, as well as other sensory properties such as fragrance,
odor and skin feel. Control of rheological properties is essential for emulsion products as they can
strongly affect consumer perception of product qualities like "richness," "smoothness," and
••stickiness"( I). In addition, change in rheological properties of an emulsion can strongly affect product
stability as, for example, a reduction in }ield value can cause serious phase separation which will almost
certainly be interpreted by consumers as a sign of an inferior or defective product.