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Innovative Scanning Electron Microscopic Techniques for Evaluating

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					                                          16,
J. Soc.Cosmet.Chem., 24, 609-622 (September 1973)




         Scanning
Innovative        Electron
MicroscopicTechniquesfor
         Hair CareProducts
Evaluating
                                                      SAL P. DxBIANCA, M.A.*



Synopsis-The utilization of microscopyin studying human hair is briefly reviewed.
Reasons for selecting the SCANNING ELECTRON MICROSCOPE (SEM) over the
transmission  electron microscopeand the optical microscopeare discussed.The use of
the SEM in evaluating HAIR CARE PRODUCTS is then described. A new technique
employing a ROTATING HAIR STAGE, specially designed and fabricated for this
study, is presented.The procedure devised allows one to view hair in the SEM while
still attached to the panelist'shead. The technique is nondestructibleto the hair, per-
mitting the study of sequentialtreatmentson the same hair. For example, the evaluation
of a shampooon the hair after 0, 5, 10, and 20 treatmentsis now possible.The hair is
removable from the SEM as many times as required for treatment without the necessity
of cutting the hair from the scalp. In addition, the apparatusallows for complete axial
rotation of the hair in the SEM.
  The functionality of two hair care products(a shampooand a conditioner)is demon-
stratedusing this technique.MICROGRAPHS of hair damages    before and after treatment
are categorizedand numericallyrated. The difference ratio was devised as an index to
measurethe degreeof improvementof damagedsites.


                                   INTRODUCTION

  In the past, evaluationof hair care productscenteredaroundsubjective
beautysalonstudies. Recently,however,the value of the scanning  electron
microscope                                                  has
           (SEM) in revealingthe effectsof hair preparations cometo
             This reportsummarizes of our investigations this area
the forefront.                      part                   into
andreveals how to employthe scanning  electron         as
                                              microscope a tool to dem-
        the             of
onstrate functionality a hair product.Beforegivingthe detailsof this

*The Mennen Co., Morristown,N.J. 07960.

                                          6O9
610      JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS

            it                              the
investigation is pertinentto brieflydescribe capabilitiesand limitations
of the threemicroscopictechniques                         why the SEM
                                   availableand demonstrate
was chosen.

                         MICROSCOPY OF HUMAN      HAIR

 The scanningelectron         has
                     microscope overcome                 of
                                           manylimitations optical
         and
microscopy conventional             electron
                         transmission                 in
                                            microscopy elucidating
the structure of human hair.
                                     one
   Usingthe opticalmicroscope, viewsa pattern of light and dark areas
           by                 or
produced the reflection passage           througha thin sliceof the specimen.    Al-
thoughhair can be viewed without interferences,                            its
                                                         while maintaining natu-
ral colors,only thoseparts that lie in the sameplane can be reproduced
sharply.Also,sincelight in the visiblerange of the spectrum the energyis
        the
source, diameterof eachpart reproduced               mustbe larger than the wave-
lengthof light. Only at low magnifications       (below 200 diameters)is the light
microscope                        the
             usefulfor showing shape         anddepthof hair.
   In orderto avoidthis problem,                     of
                                      earlystudies hair involvedthe viewingof
very thin hair disks.Only limited information         can be drawn from this tech-
nique,for onlyan extremely                   of                can
                                thin section the specimen be viewed.
   The conventional    transmission  electron  microscope   (TEM) far exceeds    the
                of
magnification the optical microscope.         This enormous    magnification (up to
200,000x) allowsthe study of detailswhich never appearedin the optical
              The
microscope. TEM image is produced monochromatic   by                  electrons that
have illuminated a specimen      which transmitsor scattersthe electrons.      Once
                      the            are                 on
pastthe specimen, electrons thenfocused a screen sheet film          or      of
              the
magnifying image.What one seesis a two-dimensional                  pattern of light
                             by
and dark areasproduced passage electrons  of            throughthe ultrathinspeci-
men.The useof ultrathinspecimens                  in
                                         results an extremely      low definition of
 depth.Sincethe transmission      electron               no
                                            microscope longerworkswith light
                the
but electrons, images                  are
                             produced not colored.
   Sample                for                         and
           preparation the TEM is complex time consuming.                 Mostbio-
                  are
logicalsalnples replicated.                           or
                                   Acetylcellulose a similarmaterialis placed
 overthe specimen    whichis wettedwith methylacetate.         After solventvolatili-
zation the replicais carefullypeeledoff. This replica, or a second        replica,is
                   In                a
now shadowed. this process heavy metal suchas platinum or gold is
             in
evaporated vacuumon the samplesurface.                What we seethen is not the
         but
sample a two-dimensional                     of                     on
                                  silhouette the metaldeposits thehair.
   Eliminatingthe opticalmicroscopy         problemof narrowdepth of field and
the transmission      electron microscope      limitations of extensivespecimen
                the
preparations, SEM has gainedpreference today's       in         research endeavors.
It is an extremely  versatile instrument              the
                                           revealing exacttopographical        struc-
                          In                       the
ture of the specimen. normaloperation, magnification                  rangeextends
 from 30x to 200,000x. The high depth of focus,a bonuscharacteristic              of
          SCANNING     ELECTRON         MICROSCOPIC   TECHNIQUES         611

the instrument,revealsextreme architecturaldetail. Sample preparationis
                                               it
relatively simple.If the sampleis conductive need only to be fastenedto
the sample                         has
            mount.Our experience sho•vn                          of
                                               that micrographs hair up to
                         by
1000x may be obtained this simplemounting         procedure. For greaterdefi-
nitionof features                    to
                  andmagnifications over 10,000x, the hair is coatedwith a
thin layer of metal,usuallya gold palladiumalloy.
  The SEM is fundamentally                                         in
                              differentfrom its TEM counterpart that the
electrons usedto producethe imagenormallyare not thosefrom the electron
        but
source lo•v-cncrgy     (secondary) electrons released                  of
                                                       from the surface the
sample.Althoughthe signalis typically producedby thesesecondary          elec-
                                  by
trons,an imagecanbe produced any signalresulting          from the interaction
of the high electronsource with the sample.Suchinteraction   produces X-rays,
uv radiation,deflected(backscattered)                ir
                                          electrons, radiation,etc., all of
                             system
•vhich•viththe properdetection                  an
                                    couldproduce appropriate signal.
   The high-energy                      from a heatedtungsten
                  beam,usuallyoriginating                   source,
              alemagnified, focused producea beam spotof approxi-
is accelerated,          and         to
mately50 A. Deflectioncoilsplacedbetweenthe last lensprovidemeansfor
               of              in
X-¾ scanning the specimen a rectangular        raster.When the electron
source        the
       strikes specimen,              electrons released
                            lo•v-cncrgy        are         from the sur-
face. Thesesecondary           are
                      electrons dra•vnto a collector  and phototube.The
instrument            are
            electronics such as to producea synchronism     betweenthe
electronbeam and a spot on a cathoderay tube, resultingin a one-to-one
correspondence  betweenthe positionof the electronbeam on the specimen
                                  ray
andthat of the spoton the cathode tube.The resultis an image   produced
on a televisionscreen                                             struc-
                     allowingthe viewerto infer a three-dimensional
ture from a two-dimensional   screen.
                        for                   the
  The SEM was chosen this studybecause micrographs             produced
containmuchmoretopographical   information  than other microscopictech-
niques.The imagesproducedreveal the true surfacestructureover a •vide
                      It
rangeof magnifications. is obviousthat for evenrelativelylo•v magnifica-
tions,the SEM has distinctadvantagesover a standardoptical microscope;
for example,only the SEM could reveal cuticleuplift or fiber flyaway as
shownon Figs. 1, 2, and $.
                                    Historgt
  Electron             has              our        into
           microscopy greatlyextended insights the structure         of
                           of              to
hair. The first application the instrument this field •vas initiated by
                  in              (1).                     by
Zahnin Germany the early 1940's This •vorkwascontinued othersin
the United States,            and
                   Netherlands, Australia,andby 1948various methods  of
           the         of
replicating surface hair •vcrcdevised                because instru-
                                        (2). Ho•vcvcr,        of
                                       of
ment limitationsand the nonconductivcncss hair, little work was performed
directlyon hair itself. Most of the •vorkinvolvedthe use of a metalliccon-
ductivecoating.
619.         JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS




         Figure 1. Micrographo[ damagedhair fiber (250X) showingexposedcortex




              .,,'.:%.. •.'•.•,,;..:•.•.:":::....•.. .-.-c',,....'
                    '..'•.'.
  ,."'."'•';..;...::;:            ,-i- '.:. .......... .?--:...•..•-•:•....::¾:•-; '--
                                :'":.                                •,•••'";'•;.
  • -..:-•,•'.. .• ......
  ø'
              ..., ß .•         .:;':,     .... .•
                            '* ....,,. .........
                                                       ....    •..
                                     '-"• •,•.,,.,..'•'•." • ' ....
                                                    'r'.:.-'•.'..
                                                                         .... .; '*' ..... ....
                                                                      "".;::'""':'.Z•"'•...... .." '-"•'•'.
                                                                               .... ...,...•.
                                                                      ' ?'
                                                                                                ,••...••..•......•..•,..,•,•;.,..
                                                                                             • --'-•'•-'••'         .
                                                                                                               -:•r-½        .:.'
    a... ,. % "      •. % .*,,.                    .
                                             . ',-,,,, . .½•.                                     .::..:-..-.-. ...
                                                                      . .•,f%.•.•--:c•..;-'.'-.-.•-•-,,                      .-
     •         ,    ,•.""            • .... .,.. :.?,-.,?:•:..•.-•,-•......•,.............:-.
    •'     • ,.'"• "'•.                                           '"'../'-'-
                                    '-i.. "....'"'"'??S?'"--,.•?."•'•:/:" .....

                                              o[
                            Figure2. Micrograph hair fiberpulledapart(300X)
           SCANNING ELECTRON MICROSCOPIC TECHNIQUES                                   613




  Figure 3. Micrographof hair fiber pulled into a kn3t (800X) (note severecuticleuplift)



  XVolframand Lindemannemployedthe SEM to reveal the morphological
              of
characteristics hair (3). They pointedout that the cuticle,often neglected
                 the
when considering stress-strain              of
                                 properties hair, may in reality have a
          effect.The concept cuticle-cortex
substantial                  of                                   to
                                              ratio wasproposed explain
                   properties hair. It was found that the level of super-
the supercontraction          of
contractiondecreaseswith increasingrelative cuticle (decreasingfiber diame-
ter).
                    the
  Swift investigated architectural          of
                                    changes hair surfaces   resultingfrom
simpletoiletrytreatments (4). Althoughthisstudygivessome           in
                                                           insights how
to choosethose productswith optimum characteristics     (e.g., cleaningby
              it
shampooing), still impliesthat manyhairsmustbe evaluated.
  Ayer and Thompson(5) utilized the SEM to stndy the coatabilityof hair
                                                                   the,.
sprayfihnson individual and small groupsof hairs.They investigated use
                     to
of severalsurfactants improvethe coatabilityand improvethe properties
of hair spray formulationssuchas luster and flaking. The techniqueinvolved
sprayinga hair swatch,drying,and gluingit to a mount.The samplewas then
       with a gold film, placedin the SEM, and viewed.
shadowed
614      JOURNAL OF THE SOCIETY OF COSMETIC                 CHEMISTS

                                 EXPERIMENTAL

                              Rotating Hair Stage
  All previous SEM studies of hair suffer from the primary experimental
diffculty that hair exhibitsconsiderable                not
                                         heterogeneity onlyfrom person      to
person but alsobetweenhairsfrom the samepersonand evendifferentsec-
tionsalongthe samehair shaR.Consequently,                         the
                                                  when studying effectof a
productit is extremelycliffcult to conclude    that a particularfeatureresulted
from the treatmentand did not alreadyexistprior to the treatment.
  In orderto overcome    thesedrawbacks    that have in the pastbeentakenfor
                              to             a
grantedas being impossible overcome, rotating hair stage (RHS)* was
designedand fabricated (Figs. 4 and 5). The RHS providesfor mounting
four differenthair shafts,each of which could be rotated aroundits axisby
controls externalto the microscope  vacuumsystem.      After severalattempts,a
            sea]
satisfactory was developed                  of
                                 consisting a brassscrew-on     nut, beveledon
the inside,into which fit a carefully slit beveled rubber groinmet.When the
hairswere placedin the slit, the pressure              by
                                            produced the beveledscrew-on
                  to
nut wassufficient producean excellent      high vacuumseal.
   The rotatinghair stageallowedus to make a completely        valid evalu.ation
of hair before and after treatment.The RHS and the SEM parameters         used
         in
resulted the ability to performthe following:
  1. The identical   area on the same hair was evaluated      in the before and
                         In
     after micrographs. order to ensurethis, completeaxial rotation in
     additionto the normal X-Y rotationof the SEM was performed,reveal-
                                of
     ing the entire circumference the hair.
  2. The hair remainedon the panelist's  head when applyingthe product.
     The RHS allowed taking the samplein and out of ,the SEM without
     cuttingthe hair from the scalp.
  3. The SEM instrumentparameters     were adiustedto obtain micrographs
      of hair without applyinga conductive metallic c•ating. In otherwords,
     no specialtreatmentwas givento the varioushair samples.   The charging
     problems,normally encountered,     were minimized by operatingthe
     SEM a•treducedaccelerating    voltages(10 kv rather than 30 kv), low
     beam currents,and very specificsettingsfor the condenser      lens and
     detectorpower supply.
                                  Test Protocol

                                                                 no
  Only girls with hair longer than 18 in. in length were selected; other
             were used.Eighteenincheswas our estimateof the minimum
qualifications
length requiredfor gettingthe hairs into and out of the microscopewithout
breaking.
*Designedjointly by the Mennen Co., Morristown,N.J., and StructureProbe Inc., West
Chester,Pa.
SCANNING         ELECTRON      MICROSCOPIC                        TECHNIQUES   615




         .....                   I    Ilfilfillllll   .........



                   Figure 4. Rotating hair stage
         A. Externalknobsfor rotatinghair shafts
         B. Face plate for bolting into microscope
         C. Vacuum seals for cables
         D. Cable stabilizer
         E. 4 mountingslotsfor mounting 4 hair shafts




Figure 5. Rotating hair stageshowingrubber grommetvacuum seal
                     A. Slit rnbber grommet
                     B. Beveled nut
616       JOURNAL OF THE SOCIETY OF COSMETIC                  CHEMISTS

  No effort was made to use panelists    •vith or without any particularhair
types (virgin, bleached,dyed, etc.), textures(fine, medium,coarse),amounts
(thin, average,thick), and condition(oily, normal,dry). Table I showsthe
            of
percentages differentcategories   finally selected.
                                      Table   I
                        Breakdown Panelists'
              Statistical        of        Hair Usedin Testinga
                    Types                                  Amounts
         Virgin                  67               Thin                 12
         Bleached                25               Thick                41
         Dyed                     8               Average              47
                  Textures                                 Condition
         Fine                    46               Oily                 47
         Medium                  50               Dry                   2
         Coarse                   4               Normal               51


"Figures given as percentages.

  Each of four selectedhairs was color tagged near the scalp, then care-
fully fed throughthe rotatinghair stage.The hairs were not conditioned     or
treatedin any way. They xvere  held in placewith silver-plated woodentooth-
pick ends.After providingsuffleient   slackin the device,the rubber grommet
     put                                           the
xvas in place,with the four hairsfitting xvithin slit. The apparatus     was
thenboltedinto the opensidepostof the SEM.
   Usingthe television                                 the
                        scanmode of the instrument, damagedareasof
each hair xverelocated. In some easesthe damagedareaswere located at
considerable   distancesalongthe hair shaft.To photograph      suchdamages,
montages             of
           consisting as manyas 8-10 individualphotographs        were made.
Also,high magnification  micrographs   were madeof selected   damagedareas.
The panelist's hair wasremoved  from the instrument                   number
                                                     after a suffleient
of "before" treatmentmicrographs   xvere taken.
  The hairsxvereremovedfrom the rotatinghair stageand allowedto fall
backinto place.The hairswere now randomly                   and
                                                distributed for all practi-
cal purposes                           on
              weresimilarto all others the head.That is, whenthe product
was applied,thesehairs receivedno specialtreatment.For the shampoo
          the
product, hair wasshampooed                         six
                                  (txvolatherings) times.    After eachsham-
         the
pooing, hair wasthoroughly       rinsedand driedwith an electricdrier. The
ha;rconditioner          a
                 product, leave-on   type,xvas appliedto slightlywet hair and
           dried.After treatment panelist's
electrically                   the        tagged                to
                                                hairswerereturned
the instrumentand the "after" micrographstaken.
              the               of                      it,
  By viexving hairby means the TV modeandrotating we wereable
                                                    the
to find the exactarea of the hair shaftand photograph repairedarea.In
         to
addition the photographs,videotapedatawerealsocollected.This ability
                   of                          it
to view the scanning a hair shaftwhile rotating allowsoneto visually
            SCANNING ELECTRON MICROSCOPICTECHNIQUES                   617

         the         of                           data contain,
appreciate improvement eachhair shaft.The videotape
                   a
for severalreasons, considerably greateramountof informationthan could
ever be recordedon Polaroidfilm. Of thesereasons,  perhapsthe most im-
portantis the fact that considerablyhigher magnificationinformation  can
             on
be recorded videotape.This is possible    becauseany image drift, which
would ruin a 50-secphotographic  exposure, doesnot have this catastrophic
                        All            is            by
effectwhen videotaping. videotaping accompanied narrationwhich
also documents  the panelist'snumber, and time and place the data were
recorded.

                         DISCUSSION AND I•ESULTS

                            of
   Healthy hair is composed threeproteinaceous   layers:the medulla,which
is the central core-rarely found throughoutthe entire shaft; the cortex,ex-
tremelylongfibrilscomprising   mostof the hairsvolume;and the cuticle,the
outer layer of overlapping  plates.After enduringseveralyearsof exposure,
          and
abrasion, styling,evenwell-treatedhair becomes     damaged.
   After viewing many hairs under the SEM, it was found th.at,with some
               the
overlapping, damageareascould be classified     into four generalcate-
gories                    exposed
      (i.e., flyawayfibers,           split ends,and general
                                cortex,                     shaftdam-
age).




                                     .....
                            ..•.• ..•:•

                               .:•...1.•: .:.....
                               ß




                                            ß
                                    "? .7!:':
                                         ,. }


                                              ß •.




                                               ..•.
                                               ß •:?::




                                                  fibers
                   Figure 6. Damagecategory-flyaway
618         JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS

            of            are      in
  Examples eachcategory shown Figs.6 through9. Also,a dramatic
                                from               showing im-
pair of beforeandaftermicrographs an actualpanelist,     the
provement                    is      in
            after treatment, shown Figs. 10 and 11.
  To evaluatethe degreeof improvement      resultingfrom the producttreat-
ment a numerical    system  was required.The difference ratio (DR), which is
                      the               of
an indexto measure improvement eachdamaged              site,wasdevisedand
found to be a meaningful            to              the
                             system communicate repair without being
misleading.
                   and                          was
  Each"before" "after"pair of micrographs classified oneof the into
four mentioned   damage   types,and eachdamage                a
                                                 siteassigned danaage point
                                                      the
from 0 to 4. (The higherthe nulnberthe more severe damage.)The DR
for ('achsitemay be calculated  by:

                   =    points treatment
                 DR damage after
                           pointsbeforetreatment
                      damage
                          no
  A value of 1.0 indicates changewith treatment.DR valuesbelow 1.0
shoxv              of         site
     improvement a danaage and thoseabove1.0 indicateadditional
danaageresultingfrom the treatment.A summaryof the resultsis listed in
Table II.




                                                   cortex
                    Figure 7. Damagecategory-exposed
SCANNING   ELECTRON      MICROSCOPIC      TECHNIQUES   619




                                         end
           Figure 8. Damagecategory--split




                                    shaftdamage
     Figure 9. Damagecategory-general
620      JOURNAL OF THE SOCIETY OF COSMETIC CHEMIST$




Figure 10. Micrograph of general shaft damage before treatment with conditioning
                                       formulation




                                        Table   II
                              Difference Ratio (DR) Values
                                                               •
                                                     Conditioner         •
                                                                   Shampoo
      Total number of panelists                         50           15
      Total   number   of hairs evaluated              192           59
      Total number of damage sites evaluated           442           127
      Average difference ratio calculated                 0.26         0.47
      DR range per panelist                           0.03--0.66   0.28-0.71

"Shampoo and leave-on conditionersuppliedby the Mennen Co., Morristown, N.J. Both
productsare protein formulations.
         SCANNING ELECTRON MICROSCOPIC TECHNIQUES                                                                                                 6•1



               -   .




                           ..




                       .        -:..:
                                 .


                                     ...



                                           :.:


                                                                      .




                                              -•,
                                           -.?.•                                         .
                                                                                 -(,:/.•..:"*'•
                                                          :}'.•...                     •,,--:•: :...

                                                      '-.%..,,
                                                            .•¾
                                                    .... .½•.•..•
                                                  -. \    ":'?                             •
                                                                                       ::•-, •.•..



                                           ,             -.:
                                                          .....                               <• •.-•'
                                                                            '•.
                                                                  .              •..               ....                  •..
                                                                                                                      :•.•

                                                                                       .


                                                                          ....




                                                                                                                               .? :•

                                                                                           • ß                   •              '"'



                                                                                                           ..
                                                                                                     .




                                                                                                          .:
                                                                                                                ...




                    of                             repair of shaftdamage
Figure 11. Micrograph samearea as in Fig. 10 showing                    with
                                                 one applicationof conditioner

  A closer lookat the damage categories        that split endsaccount
                                        revealed                     for
35%of all hair damage  studies       III
                              (Tables and IV). Flyawayfibersand gen-
eral shaftdamage werefoundin 32 and25%of the damaged           respective-
                                                          sites,
ly.
                                                                          Table              III
                                                 Results of Shampoo Treatment
                                                                                                               Category                Per Cent
             DamageCategory                                                                                    Per Cent                Improved
             Flyaway fibers                                                                                            35                 93
             Exposed cortex                                                                                             7                 88
             Split ends                                                                                                35                 60
             Shaft damage                                                                                              23                 93
622       JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS

                                        Table IV
                            Results of Conditioner   Treatment

                                                     Category         Per Cent
                DamageCategory                       PerCent         Improved
                Flyaway fibersfrom cuticle              28                94
                Exposedcortex                            8                93
                 Split ends                             35                95
                 General shaft damage                   26                92
                Miscellaneous                            3               80


  Thisstudydemonstrates                of
                          improvement all damage    typesaftertreatment.
For example,        on
               based a minimum             of
                                 reduction onedamage      point in our rat-
ing system,                         site
            over90%of the damaged improved       after treatment  with the
hair conditioning            In                    actuallydosed60%of
                  formulation. fact, the conditioner
                         to
the split ends(improved zero column).     The shampoo   formulation tested
           all
improved typesof hair damage(Table III). This studynot .onlydemon-
stratesimprovementof damage sites but revealsthe products'ability to
repair different types of damages.

                                         SU1VI•ARY

             approach evaluatehair careproducts
  A systematic        to                      usingthe SEM has
beendeveloped.              employing rot.
               The technioue,       a ating hair stage(RHS) al-
lows for maximumrotational freedom of the hair in the SEM. The hair, while
still attachedto the scalp,may be removed                into the SEM
                                         and re-introduced
as often as necessary.
  The difference   ratio (DR), a numericalsystemshowingthe degreeof
change,revealedsignificant              of
                             improvement damagedsitesafter treatment
with a hair conditioner and shampoo.

                                   ACKNOWLEDGMENT

  The author is grateful to Dr. C. Garber, Presidentof StructureProbeInc.,
for his continuing                       All
                  effortsand suggestions. micrographs     shownwere taken
at Structure Probe Inc.

                                                             ( Received       29,
                                                                       January 1973)

                                       REFERENCES

(1) Fraser, R. D. B., and Rogers,G. E., Aust. ]. Biol. Sci., 8, 129 (1955).
(2) Barnes,R. B., Burton, C. J., and Scott, R. G., Electron microscopical     replica technique
                                    J.
    for the studyof organicsurfaces, Appl. Phys.,16, 730 (1945).
(3) Wolfram, J. L., and Lindemann, M. K. O., Some observationson the hair cuticle,
    ]. Soc.Cosmet.Chem., 22, 839 (1971).
                                   in
(4) Swift, J. A., New developments electronmicroscopy,        Ibid., 22, 477 (1971).
(5) Ayer, P. A., and Thompson, J. A., Scanning electron microscopyand other new
                 to
    approaches hair spray evaluation,Ibid., 23, 617 (1972).

				
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