Evaluation Of Shampoos 70m66

J. Soc. CosmeticCheviists,17, 539-551 (1966)

The Practical

Evaluation

of

Shampoos MARSHALL

SORKIN,

M.S., BERTRAM

SHAPIRO, B.S., and GUS S. KASS, B.S.*

PresentedDecember1, 1965, New York City

Synopsis•ppearance, performance during use, and effect on hair after use are the three major criteria by which shampoosshouldbe evaluated. Within these three broad categories, 25 separate characteristics arc enumerated. The importance of each of these and laboratory and beauty salon test proceduresfor evaluating shampoosare discussed.

INTRODUCTION

The developmentof a shampoothat can win a significantshareof a highly competitivemarket is not a simpletask. Even thougha shampoo is more or lessa rather prosaictoiletry, many of its qualities, or lack of these qualities, can affect the consumereither favorably or adversely. The chancesof developinga utility shampoowith a significantinnovation are rather remote. The term utility shampoois usedto differentiate between the generaluse shampooand those which are more specifically defined, such as antidandruff shampoos,color shampoos,etc. In order to producea successfulshampooof the utility type, it must have a quality of excellencebuilt into it. This quality of excellenceis almost always a total combination of many factors, some of which are immediately obviousto the consumerand many of which are not. The consumerreacts to a shampoo at three different times. The consumerwill be consideredto be female, sincealmost all of the general use family shampoois purchasedby a feminine member of the family. * Alberto-Culver Company, Melrose Park, Ill. 539

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It is true that her decisionis influencedby advertising, packaging,brand name, and reputation of the manufacturer--and, perhaps a great deal more than one would like to it, by price. Her first real impressions are established when she picks the package off the shelf. If she is favorably impressedat that time she may buy and use the shampoo. Her decisionwhether to purchasethe product again is influenced twice more. How did the shampooperform, and how did it leave her hair ? Most discussions of shampooperformancefound in the literature are limited to evaluation of foaming qualities, manageability, and detergency. There are many other factors that contribute to a quality shampoo,which have been delineatedin 25 distinct categories. Every shampoounder development and all competitive shampoosare evaluated against this checklist. Many of the qualities can be measuredby well-establishedlaboratory procedures. Others must be evaluated by specially devised techniques. And still other qualities can only be determinedsubjectively,and hereexperienceand a thoroughunderstanding of shampoosare invaluable. Details of the formulation or compositionof shampooswill not be considered. Instead, the major objectiveis a discussionof the practical evaluation of the 25 characteristicsor qualitieswhich enablethe chemist to determinewhether or not a shampoohas that certain "quality of excellence," as measured by the consumer. These qualities are reviewed not necessarilyin order of importance; nor are they studied in the order shown; and many of them are interrelated. The methods of evaluation as describedin this paper apply to a clear liquid shampoo although similar criteria may be applied to a liquid lotion or a cream shampoo. The 25 shampooqualities can be divided into three broad groups. This is primarily a checklist designedfor the fairly rapid evaluation of large numbers of shampooson a routine basis. The first group concerns the appearanceof the product itself in the bottle and includesthe following nine qualities for evaluation: 1. Clarity 2. Viscosity 3.

Color

4. Color stability 5. Cloud point 6. Clear point 7. pH

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Fragrance Sterility

The second group of qualities relates to or is directly concerned with the actual performanceon the hair and includes: 10. 11. 12. 13.

Foam Foam Foam Foam

production--hard water production--soft water production--hard water plus soil stability

14.

Foam

texture

15. 16. 17.

Speed of foam production Rinseability Fragrance of lather

The third groupof characteristicsconcernsthe effectof the shampoo on both the hair and skin. Here the followingqualitiesare evaluated: 18. Combability of wet hair 19. Combability of dry hair 20. Static electricity of the hair 21. 22.

Fragrance of the hair Hair gloss

23.

Effect

24.

Staining of bleached or permanent waved hair

on artificial

hair color

25.

Feel on hands

SHAMPOO EVALUATION

Clarity

From a consumerpoint of view, the general outward appearanceof the shampoois the first with the product itself, stripped of its outer coveringof label and package. For this reasonit is most important that a clear shampoo be manufactured with maximum care. A shampoowith sparkling clarity has obviouslygreater consumerappeal that one that is hazy. The danger in formulating clear shampoosis loss of clarity with aging, a fairly commondefect. Only thorough stability testing of the shampoowill reveal this problem so that measurescan be taken to solve it. Among the factors contributing to lossof clarity are temperature, perfume, water hardness,contaminationby microorganisms,and waterinsolublefatty compoundsusedas hair conditioningagents. Cloud point and clear point evaluationsare important in order to maintain clarity under a range of colder-than-normaltemperatures.

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The cloud point is the highest temperature at which the shampoowill cloud or haze when cooled. The clear point is the lowest temperature at which the product will clear when warmed from a chilled opaque condition. They are not always the same. Clarity, insofar as cloud and clearpointsare concerned,shouldbe maintained at about a maximum of 10 øC. This should insure clarity in storesand homesunder average conditions of temperature. Viscosity

Liquid shampooscomprisethe largest share of the shampoomarket, with clearliquid shampoosingfor better than 50% of the market. Among the most important characteristicsof these productsis viscosity which may range from water-thin products to viscousliquids. There are both psychologicaland practical advantages to relatively high viscosity liquid shampoos. They often imply a high. concentration of shampooingredients plus a richness that is usually associatedwith hair conditioningand management. There is also a practical value. High viscosityliquid shampooscan be pouredinto the palm of the hand for application to the hair, thus eliminating dripping through the fingers or down the face and neck.

A desirable viscosity range will vary between 500 and 1500 s. Shampooshaving viscositiesbelow this level tend to be runny; and if the viscosity is over 2000 s., they may not pour too well. Maintaining viscosity within a close range over a long period of time can sometimes be a problem. Here again, stability testing is of utmost importance. Color

A shampoomay be uncolored, or it may have certified color added. The color of a shampoois dictated by esthetic considerations,packaging, and subtle psychologicalfactors. The market to which it is directed is alsoa factor. A shampoofor men may be blue, green, amber, or gold, or it may be colorless,but pink would be a doubtful choice. There has been a transition over the years in the colorswhich the consumer prefers. Until recent years liquid shampooswere usually amber, yellow, or orange. More recently, green and blue shampoos have become popular. Clear, colorlessshampoosare also on the market. Such shadesas lavender and red and deep colors are particularly unacceptable.

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( 'olor •¾tab ilit y

In selecting the color to be used, color stability or instability can become a problem. Many of the certified dyes used are sensitive to light, pH, and other chemical factors. It should be unnecessaryto state that every shampooshouldbe thoroughly tested for light stability. Sinceit is not always convenientto set the product in the sun and since the results are not reproducible, a commercial "fadeometer" may be used to determine color stability. In such equipment the shampoois

exposedto high intensity ultraviolet light under controlled conditions. A minimum exposureof six hours with negligible or no color changeis usually consideredacceptable. Incidentally, oneof the pitfalls to be avoidedin light exposurestudies is to test the shampooin a containermade from the samematerial as the ultimate package. It is not unusual to find a color that may fade in glassbut is stable in a given plastic and viceversa. With the de-listing of many certified colors,the problem of finding a suitable color that is stable to light has increased. The use of ultraviolet absorbents in the shampoo can be extremely helpful in improving the light stability of fugitive colors. Some container manufacturers are coating their glass or plastic bottles with ultraviolet absorbentswhich serve the same purpose.

A third area where the color of a shampooshould be evaluated is one that is frequently overlooked. Some hair, and this is especially true of bleachedand permanently waved hair, is quite porousand may absorb the color from the shampoo. Here again, pH and chemical compositionof the product may be contributingfactors. Only thorough testing on laboratory hair swatchesand subsequentapplication to subjects with bleachedor permanently waved hair will determine whether this problem exists. pH

The pH of a shampoomay have definiteeffectsupon its properties. Most liquid shampoostoday are formulated to have a pH between 6.5 and 8.5. Within this range a suitableviscosityand clarity can usually be achieved,as well as goodstability and lathering properties. A few generalizationscan be made concerningthe effectsof pH on a typical clear shampooformulation: 1. Shampoosformulated on the high side of the pH range will exhibit a greater degree of foaming and cleansing as well as a greater ability to strip the natural oils from the hair.

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Conversely, shampooson the low side of the range will generally leave the hair in better condition with a greater degree of manageability and combability. Shampooswith pH's above and beyond the high side of the range can causeeye irritation more readily than those within the range. It is easierto maintain clarity on the high side of the pH range. Viscosity generally increases as the pH is lowered. This is

especiallytrue of alkylolamide-laurylsulfate shampoos. pH can, therefore, be consideredas a key factor in formulating a product to suit the consumer'sdesires. Although she may never have heard of the term, pH can affect the appearance,efficacy,and residual performanceof a shampoo. Fragrance

The fragrance of a shampoois a most important quality. It can add a touch of cosmetic eleganceto the product plus an air of distinction. It can significantly influence the consumer whether or not to purchasethe product initially or to repurchase it. It is the authors' opinion that a shampoofragrance should be a light and clean bouquet; but the perfume type will be dictated by whether the shampoo is marketed primarily to women, men, children, or for family use. The shampoo fragrance should be evaluated critically at three dif-

ferent stages. First, the productitself in the bottle. A buye) will often remove the cap and sniff the product at the shelf or counter. Does it have a light refreshing scent with high appeal? Is the shampoofree of a chemical or detergent odor; is it effectively masked? Does the fragrance appeal to the consumergroup to whom the shampoois directed? The fragrance at point of purchasecan often make or prevent a sale.

The secondtime that the fragrance may elicit a responsefrom the consumeris during application to the hair. The use of hot water plus the fact that shampoosare often applied to the hair in a confinedarea, such as the bathroom or shower,can result in a fragrance changenoticeable in the lather and in the atmosphere. The fragrance should retain its basic characteristicswithout becoming overpowering. The third important stageis the fragranceof the hair after shampooing. The hair should retain an almost imperceptiblescent. Certain perfumetypes shouldbe avoided,suchas heavy, sweettypes which tend to cling to the hair. Hair that hasbeenbleachedor permanentlywaved

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tends to retain more of the fragrance than chemically untreated hair. Also, hair that hasbeen shampooedwith productscontainingamphoteric surfactants often retains more fragrance than when anionic surfactants are used.

Sterility For some reason cosmeticchemists often disregard or minimize the potential problemof shampoocontaminationby microorganisms. They would not consider marketing a cream or lotion that is inadequately preserved,but shampoosare often found without preservatives. There is a mistaken notion that, since sulfated lauryl alcohol and sulfated ethers are consideredantagonistic to bacterial and fungal growth, no contamination problems exist in shampoos. Several investigators

(1, 2) have shownthat this is only partly true, and shampoos are often found that give high bacterial counts--particularly of gram-negative bacteria. This has been confirmedby the authors' experienceover the years. Contamination by microorganismsposes not only a health hazard but can cause changesin the shampoo, such as malodor, turbidity, and viscosity changes. On the other hand, it is also possibleto find grosslycontaminated products without visible signsof change. All shampoosmust be preservednot only for original freedom from contamination but also must be protected against the possibility of future contaminationwhen the packageis openedand reopenedfor use. Many preservativesare available for use in shampoostoday, and their incorporation is fairly simple; however, their effect on certain organisms may either diminish in time or causethe generation of resistant strains. Thus, evenafter many years of preservationby specificagentshave ed safely, a periodic investigation should be undertaken to determine whether the preservatives are still effective. Freedom from microorganismsnot only dependson adequate preservation but also upon uncontaminated raw materials--particularly water. Vitally essential are strict sanitary measures during manufacture. Constant diligence is required, and development production shampoosshould be routinely subjectedto bacteriologicalevaluation. Foaming

To the consumer, foaming or lathering action is one of the most important aspectsin determining the quality of a shampoo,and the measurement

of foam has received much attention

in the literature.

The

volume, foam structure, foam viscosity, and foam stability are also

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important criteria by which the consumerjudges the shampooeven though she may not realize it. Undoubtedly, techniques to measure and evaluate foaming qualities are important. Normally, suchmeasurements are first performed in the laboratory and then in actual use on models. There have been many laboratory techniquesdevelopedover the years to measure foam, some of them highly sophisticated. The authors use a very simple techniquewhich requiresonly a 500 ml glass stopperedcylinder and a device to revolve or agitate it. This very simple method has been widely criticized, and there are more precise procedures(3-5). For practical purposesand after thousandsof foam

tIt /" ,

/

/

'

SOFT

-----

VERY HARD WATER (310ppm)

WRY

U•D

WAT•

/

/'

VOLUME OF 10% SIIA24P00 SOLUTION

Figure 1. Foam curves of a commercial shampoo (Shampoo A)

tests, this technique has been found to meet the following conditions: It is fast, it is reproducible,and it reflectsthe performanceof the shampoo on the hair.

First, 10% dilutionsof the shampooin either soft water or water of known hardnessare prepared. Increasing increments of the diluted shampooare pipetted into the cylinder, diluted with water of required hardnessto a fixed level, and then rotated for a precisenumber of times. The foam volume is recorded, and the bubble structure and foam sta-

bility are examined. Three foam curvesare plotted for every shampoo: A soft water dilution;

a dilution with water of known hardness; and

a dilutionof waterwith knownhardness plusthe additionof 1 ml of olive oil. The foam determinationin the presenceof oil fairly accurately

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reflects the performance of the shampoo on the first lathering. During the first lathering the foam is often depressedbecauseof sebum, hair dressings,and other cosmetiroducts which may be on the hair. The hard and soft water curves represent the range of water hardness used by consumersthroughout the country and can be a major factor in the type of foam developed. Figure 1 illustrates these three foam curves of a nationally d brand of shampoo. Figure 2 shows

the foam curvesin very hard water (310 p.p.m.) of two popular shampoos. This significant difference in foam production of shampoos A and B is also evident when the two shampoosare actually applied to the hair of a subject using a "half-head" technique.

•oo

200

100

VOLb"t'IE0P

50LUT10•

Figure 2. Comparisonof the foam volume of two shampoosin very hard water (810 ppm)

The most important test in evaluating shampooperformanceis to shampooa variety of hair types under controlledconditionsand observe the results. The recommended method is the "half-head" technique

which involvesparting the hair down the center and shampooingeach half simultaneouslywith two different shampoos. The "half-head" techniqueis commonlyusedwith many hair preparationssuchas hair sprays,wave sets, hair dressings,etc. With these,"half-head"testing is simpleand easy, but it is not quite so simplewith a shampoo. The reasons for "half-head" testing are quite obvious. No two headsof hair are the same. The hair varies in texture, length, condition, sebumand soil content, and presenceof cosmetics. Therefore, cornpar-

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ing ShampooA on one headwith ShampooB on anotherhead is rather meaningless,especiallyif only subtle differencesexist. One must then rely on memory and, therefore,cannot comparethe results of a head shampooedwith product A and subsequentlytreated with shampooB. A skilled beautician can apply two shampoosto the samehead and, if done on a number of heads,obtain meaningful and reproducibleresults. Two shampoosare applied to dampened hair in equal amounts (from glasshypodermicsyringesfor accuracyand convenience)to both sides. The lather is worked up as uniformly as possibleon both sidesof the head and the various lathering and foaming qualities observed,includingthe speedat which the lather develops,the so-called "flash-foam" characteristics. A secondlather is worked up, again using

syringesfor accuratedispensingof the shampoo,and the evaluationis repeated. Very often the secondlather is allowed to remain on the hair for three to five minutes and foam collapse,if any, noted. The shampoosare rinsed from the hair and the rinsing characteristicsobserved. It has been found that some shampoos rinse very rapidly

while others continueto producefoam for severalminutes during the rinsing procedure. The foam texture is also examined during these tests. Foam made

up of large, thin bubblesis not desirable;neitheris foam made up of very smallbubbles,which tend to make the foam feel like a cream. Incidentally, one observationmade duringthese"half-head"testsis frequentlyoverlooked. How doesthe shampoofeel on the handsduring application? Does the shampoo impart the desirable soap-like lubricity, or doesit impart a raspyharshfeelto the hands? The consumer has been conditionedto the feeling of lubricity or slip that is always characteristicof soap and most shampoos. With the current trend to shampoosof lower pH, this quality can be lost. A shampooof pH 6.0 to 6.5 can lack this feelingof lubricity on the hands,but the problem can be resolvedby skillful formulation. Manageability

Perhapsone of the most abusedwordsusedin shampooadvertising is "manageability" or "conditioning." Such claims are frequently madefor shampoos,even though they do not exist. However,they are meaningfulto the consumerand are, therefore,importantto the chemist. Just what do thesewordsmean? A healthy, normalheadof hair is one that is easily combedwhen either wet or dry. This is due to natural secretionswhich coat the hair with a lubricating film, eliminate

PRACTICAL

EVALUATION CLINIC

Date

Subject

Short

Medium

Tinted

Bleached

SIIAMPO0

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T•ST

Ph.

DESCRIPTION

OF HAIR

Long P.W.

Date

Normal

Oily

Fine

Medium

Coarse

Good

Fair

Poor

Date of Last Shampoo

Shampoo Used

LEFT

RIGHT

Shampoo Used Dilution Amount

1st

1st

Slew

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Foaming

2nd 1st

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Heavy

Volume

2nd 1st

Av.

Fast

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Av.

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2nd 1st

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Density

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0 1 2 3 4 5 0 1 223

4 5

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3

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5

O 1 2 3 4 5

012345

Rinsability

o

•

•

•

h

5

Feel-Wet

o

•

•

•

•

5

Combability-Wet

o

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5

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Static Charge

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345

0

1

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34

0 1 2 3 4 5 O !

2 3 4

0 1 2 3 h 5

Body

0

Sheen

Other

Call

Slew 2nd 1st

1

2

3

4

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5

Comments

Back

Comments

Date

Figure 3.

Bcauty Clinic form

staticcharges, and impart glossor sheen. Many shampoos will completely strip the hair of sebumand other natural secretions,with the resultthat the wet hair snarlsor tanglesand is difficultto comb. The

dry hair is oftenlustreless and alsodifficultto comb. A strongstatic chargeresultsin "fly-away"or hair difficultto holdin place. There are two solutionsto this problem. One is to formulate a shampoowith reduceddetergency. The shampoowill removesurface

soil on the hair and most--but not all---of the sebumcoating. The amountof naturaloilsremainingonthe hair is sufficient to impart some

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degree of "manageability." A secondsolution is to compound a shampoo that will cleansethe hair but still leave a film on it to serve temporarily as a conditioning agent until natural scalp secretionsare replaced. The authors doubt that most so-called "conditioning agents" incorporated in shampoosare depositedon the hair. There are, however, substantive materials which are useful for this purpose. After the hair has been thoroughly rinsed and towel dried, it is again parted down the center and combed (using two identical clean combs) by both the beautician and the chemist, and differencesin combability are noted. No other cosmetic products are used on the hair when shampoosare evaluated. When dry, the hair is again checked for dry combability, gloss, and static charge. Excellent methods have been devisedfor the measurementof static chargeon hair (6, 7) but for routine purposesvisual observationis sufficient. All beauty clinic observations are recorded on the form shown in Fig. 3. A subjective rating system is used whereby many of the characteristicsdiscussedabove are scoredfrom 0 to 5, with 0 being very poor and 5 very good. In a series of tests on a shampoo,using suitable controls, meaningful observations are readily made as to the performancecharacteristics.

t•ffect of Shampooon Hair Color In view of the tremendousgrowth of hair coloring, the possibleeffects of shampooson artificially colored hair cannot be ignored. Specialty shampooshave been developedfor use on color treated hair, but utility shampoosshould also be checked. This is routinely performed in the laboratory and in the beauty clinic on hair that has been colored with oxidation dyes and with semi-permanent dyes. In the laboratory, the AATCC Launderometer as modified by Goldemberg (10) is used. Observations of loss of color during shampooingand of color changes are made. Here again the "half-head" technique is usefulbecausecolor changesand attrition of color may be due primarily to the color and not to the shampoo. CONCLUDING COMMENTS

There are additional shampooqualities that require evaluation, and omissionof these from the list of 25 characteristics does not necessarily minimize their importance. Safety to the consumer is of paramount importance,and certainly no shampooshouldever be marketed that is a sensitizeror an irritant to the eyes or skin. Factors that contribute to

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such hazards are well known, and Inethods to detect them are in wide-

spread use. Detergency has not been listed as an important consideration for routine evaluation. Although excellent methods have been reported for the measurementof detergency (8, 9), some cosmeticchemistsare of the opinion that a shampooshouldnot be so powerful a detergentas to strip all natural secretionsfrom the hair and scalp. Modern sham-

poosare basedon surface-activeagentsthat performthis task adequately for all practical purposes. The latitude for degree of detergencyis fairly wide. When oneconsiders that mostheadsof hair are shampooed with two applications of shampoo, the factor of detergencybecomes relatively unimportant.

(ReceivedNovember24, 1965) REFERENCES

(1) Bryce, D. M., and Smart, R., J. Soc. CosmeticChemists,16,187 (1965). (2) Schwartz, A.M., Perry, J. W., and Berch, J., SurJkceActiveAgentsand DetergentsII (1958), intersciencePublishers,Inc., N.Y. (1958). (3) Myddleton, Wm. W., J. Soc. CosmeticChemists,4, 150 (1953). (4) Bromley, J. M., Ibid., 15,631 (1964). (5) New, G. E., Proceedings of theSecondCongress of theInternationalFederationof Societies of CosmeticChemists,London, 1962. Edited by A. W. Middleton, The Macmillan Company, New York (1963).

(6) Mills, C. M., Ester, V. C., and Henkin, H., J. Soc.Cosmetic Chemists,7, 466 (1956). (7) (8) (9) (10)

Barber, R. G., and Posner, A.M., Ibid., 10, 236 (1959). Barnett, G., and Powers, D. H., Ibid., 2,219 (1951). Ervin, J. C., Ibid., 3, 81 (1952). Goldemberg, R. L., Ibid., 10, 291 (1959).