SD Warren Bulletin Specks in Printing

7/29/2019 SD Warren Bulletin Specks in Printing

1/35

Bulletin No.

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2/35

ContentsPage 2Page 4Page 8Page 10Page 12Page 14Page 16Page 18Page 20Page 24Page 26Page 28Page 30

Using This Bo okas a GuideInk HickeysPick-Outs andCoating LumpsPickingWood Vessel SegmentsFibersPitsDustWater InterferencePilingAnti-Offset SprayGlossaryWarren Paper Merchants

WARRENHow will it print?This bulletin is issued by S.D. Warren Comp anyfor the purpose of aiding the graphic arts com munity in dealing with the com plexities of the printingand lithographic process es. The informationcontained he rein is a combination of the findingsof scientists and the observations of experienc edcraftspeople. No true scientist will claim thatexisting know ledge is complete, and no sincerecraftsperson will pose as a final authority, andtherefore the text of this bulletin representsmerely the considered opinions of experiencedand thoughtful analysts.


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RecognizingSpecks inPrinting

In both sheet-fed and we b print ing,specks in printing can occur from avariety of reasons. And in order toel iminate or minimize specks on pressit is necessary to identi fy them andtrace their origin.This book is designed to :1) Define a col lection of specks inprinting.2) Show the origin of these specks.3) Outline the steps to follow totroubleshoot specks in printingon press.4) List the materials that must becol lected to properly documenta specks prob lem.5) Provide a glossary of graphicarts terms commonly usedtoday.Specks in printing are caused bymaterials which enter the printingsystem and cau se a mark or smal lnon-print area in the printed image.Specks can have one or acom binat ion of or ig ins: Ink, Press,and Paper.

t InkInk can contain materials such as skindirt, or undispersed resin andpigments which could cause specks.

^ PressDefective materials on the press, orcontaminat ion from the pressroomcan cause specks.

Most of the photographs in thisbook have been enhanced wi thenlargements which were done tosimulate a printer's loupe at 12 timesmagnification (12x). In certain caseshigher magni f icat ions were used toi l lustrate the spe ck in deta i l .

^ PaperLoose debris can be l i fted off, orpart ic les pul led from the paper'ssurface and cause specks.


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Using This Bookas a GuideIf you are ex perie ncing specks inprinting i t is imperative to obtainphysical ev idence to accuratelydemonstrate the nature of theprob lem.Throughout this book there is aseries of pic ture code s that indicatethe various materials requ ired todocumen t each p rob lem.Below, each code is introduced wi than explanat ion as to how this ev idenshould be gathered.

Information:The information required by the mil lshould be f i lled in on the co mp laintform. Gather and record ali mill ordenumbers. Ident i fy press type, presssize, pr in ting sequ ence, b lanketsused , press speed , dam pen ingsystems, and room con di t ions. It isimportant that this information benoted whi le in the pressroom.

Ink from the Can:A sample of the ink from the can (or ior ig inal container) wi ll determine thecondition of the ink as i t was receivedin the printing plant. A sample of atleast 4 ounces should be placed in aai rt ight non-porous container andsealed w i th v iny l or plast ic tap e. Eacsample should be accurately labeledas to Customer, Ink Manufacturer,Batch Number, Date of Manufactureand Pr in ting Seque nce.

Ink from the Fountain:A samp le of ink from the pressfountain, when compared to the cansample, can determine i f anycontaminat ion or ad jus tments wereintroduced to the ink while in thepressro om. A sam ple of at least 4ounces should be p laced in anairt ight non-porous container andsealed w i th v iny l or plast ic tape. Eachsample should be accurate ly labe ledas to Customer, Ink Manufacturer,Batch Number, Date of Manufacture,and Pr in ting Seque nce.


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Printed Sheets with Original Defect:It is imperative to o btain the presssheet, or signature, that containsthe actual defect being desc ribed.This sheet will be referre d to as theoriginal. When obtaining printedsheets, be sure to collect at least 12consecutive sheets, including severasheets before and after the original.Clearly identify the original by circlingit, and staple the sheets together.

Unprinted Paper:When necessary, obtain at least 12consecutive sheets of unprintedpaper that have not been throughthe press. Staple these sheetstogether and clearly label with allthe appropriate order information.Unprinted pape r is necessary todetermine if the defect occurs in thepaper before printing.

Tape Pulls:When the ink rollers, plates,blanket or sheets becomecontam inated, it is necessary toretrieve this material for furtheranalysis by the mill. A recommendedtape pull material is Cleer Adheerlaminating sheets* A strip of thismaterial can be removed from itsrelease backing, used to retrieve thematerial from the press, and thenjoined again w ith its b acking . Theback of the strip should then beclearly identified as to where thetape pull was taken. (Unit #, plate,blanket, etc.)Fountain Solution:In certain printing problems it maybe necessary to obtain a sam ple ofthe fountain solution from the presscirculating tanks. Secure a sample inan airtight plastic bottle (8 ounces areadequate). Label the bottle as to thelocation of the sam ple. Also, includeinformation on how the solution wasprepared . For example: "the m ix is2 oz. etch per 1 gallon water, and20 oz. alcohol." Be ce rtain to list anyadditives that may have been add edduring the run to correct the problem.

vSee inside back cover.


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Ink Hickeys Example of how ink skin, adhering to the plate,prevents the ink from reaching the image in thesurrounding area, creating the characteristic"donut" affect.How an ink hickey would look through a printer'sloupe.

The characteristic "donut" affect.

Ink Hickeys are caused by materialwhich is carried by the ink and areno t particles w hich originate fromthe paper.Possible sources of hickeys arepieces of ink skin, uncooked resin inthe ink or roller fragmen ts from a dryor deteriorating rubbe r ink roller.Ink skin, for example, will adhereto the plate and will reject water, butaccept ink. Because of its thickness,the particle will be inked by theform roller(s) but it will prevent inkfrom contacting the plate in thesurrounding area (Figure 1). This"ring" around the particle will notprint, creating the characteristic"donut" affect. (Figures 2 and 3)


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Ink hickeys on form rollers through a printer's loupe.

Taking a tape pull from the ink form roller.

Ink hickeys on the plate through a printer's loupe.

Taking a tape pull from the plate.

In order for a complete analysis to bedone, the particle causing the speckmust be removed from the press. Forexample, tape pull material can bepressed onto the ink former and thecontaminate removed. (Figures 4and 5)The material on the tape ca n thenbe photographed and tested todetermine its origin (Examples onpages 6 and 7).Similar procedu res can be used(Figures 6 and 7) to remove thematerial causing the ink hickey fromthe plate.If the material causing the specks isin the ink, the only poss ible so lution isto remove the ink from the fou ntainand try a different ba tch. Caution: Aclean-up of the ink system may notremove al l ink hickeys. If the problempersists, form rollers may have to beremoved, cleaned and checked forpossible roller deterioration.


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Tape pull of ink skin.

Tape pull of rubber roller fragment.

Tape pull of uncooked ink resin chips.

Visual Analysis ofTape Pulls of Ink HickeyMaterials


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Photomicrograph of ink skin.

Photomicrograph of roller fragment.

Photomicrograph of resin chip.

Chemical analysis of a rubber roller fragment.

Ink: Can

Tape Pull

I ^ Ink Skin

III

Tape pulls of the m aterials that maycause ink hickeys will be exam inedand analyzed in various ways.The photos to the far left are exampleof how some materials a ppear on thetape pull.The corresponding photomicrographto the right show the particle as itwould appear under a ScanningElectron Micros cope (S.E.M.).Further analysis can determinechemical content.

100x

11 ^ Rubber Roller Fragment

100x

^ Resin ChipM

S CIAbove is an example of a chemicalanalysis of a rubber roller fragmentindicating the presence of S (Sulfur)and CI (Chlorine). Note how thisanalysis differs from that of papercoating materials on page 9.

100x


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Pick-Outs andCoating Lumps Coating lump being pulled from the surface of thepaper.Original

3rd sheet after original.

6th sheet after original.

Pick-Outs and Coating Lumps areagglomerates of fiber or coa tingmaterial that are bound into the papercoating or adhered to the paper'ssurface.The tack of the ink, or inks, will lift thedefect from the paper's surface(Figure 1), and sometimes does notfracture the coa ting.The white non-print spec k on theoriginal sheet appears on the unitwhere the lump lifts off, and thepaper's surface below then becom esprinted with the subsequent colors. Fibers

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Eventually this lump of coating picksup ink and prints from blanket. Thethree prints above show the originalsheet and the 3 rd an d 6th sheet after.(Figures 2,3 , and 4)


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Coating lump visible through a loupe on the whitepaper before printing.

Tape pull of the coating lum p from the blanket.

Photomicrograph photo at high magnification of thecoating lump.

Chemical analysis of paper coating materials. Original White Paper Tape Pull

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This type of Pick-Out can vary insize from V32" in diameter to the sizeof a quarter (which can result in asmashed blanket). White papersamples should be obtained for closexamination. Some lumps c an beseen on the white pape r sheetsbefore p rinting. (Figure 5)Tape Pulls (Figure 6) from the blankcan be photographed and analyzedto confirm their origin. Even under thelow m agnification of a loupe, thismaterial appears as a lump of whitecoating which has been printed.Further analysis on an S.E.M. athigh mag nification will confirm thepresence of coating materials (Figure7). Note that there are no fibers inthese lumps (see pa ge 10 on CoatingPick and pa ge 12 on Wood VesselSegments).The corresponding chemical analysis(Figure 8) indicates the presence ofAl and Si (Aluminum + Silicon = clayCa (Calcium = Calcium carbonate)and Ti (Titanium Dioxide).

Al Si


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Picking Drawing show ing how the coating is picked from thesurface of the paper.Coating pick

Coating pick which is concentrated at the tail of theimage.

Coating Pick also referred to as"pep per pick ing" is the result of thetack of the ink exceeding the cohesiveor binding strength of the coatingmaterials. (Figure 1)In both sheet fed and we b printing,the tack of the ink on the paper goesup as the sheet passes through themultiple units on the press.The coating can break apart, or pickoff onto the blanket, if the initial tack ofthe ink is too high, if the pa per coatingis poorly bound, or if the setting speedof the ink and paper c omb ination istoo fast.Coating pick normally occursthroughout the image area (Figure 2),but can be more concentrate d at thetail of the im age. (Figure 3)

10


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Tail pick in the color bars as seen through a loupe.

A drawing simulating how the image will adhere tothe blanket before it is stripped away.

Original White Paper Tape Pull

Tail Pick, also known in the industrytrailing-edge pick, is the result of thehigh printing forces w hich aregenerated at the end of an imagearea where it ultimately releases fromthe blanket.Much like cracking a whip, the sheebends con forming to the blanketcylinder and, when it is pulled by thegrippers or proce eds to the nextprinting unit, the sheet snaps awayand the high force will pick thecoating just at the en d, or tail of theimage. This snapping can be clearlyheard in the pressroom .


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Wood VesselSegments Wood vessel segment being pulled from the papersurface.Looking through a printer's loupe at a wood vesselsegment that has been pulled through the sheet, buthas not picked off onto the blanket.

Photos at 30x which show the characteristic shapesof wood vessel segments.

Wood Vessel Segments are fiberswhich, because of their com position,are difficult to remove during pulpingprocedures, and tend to be poorlybound into a coated paper. (Figure 1)The tack of the ink could exc eed thebinding strength of these segmentsand pull them from the paper'ssurface leaving a ruptured spe ck.(Figure 2)Wood Vessel Segments havecharacteristic shapes a nd canquickly be identified under a lowmagnification glass by viewing theprint. (Figure 3)

12


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Debris on the blanket from wood vessel segmentspulling from the sheet.

A tape pull of a single wood vessel segment.

Original White Paper Tape Pull

The first corrective m easure takenshou ld be to try a different lot ofpaper. If any ink changes arecontemplated, the ink manufactureshould be consulted immediately.Vessel segments w ill appe ar as whiparticles on the blanket.(Figure 4 inset)A tape pull should be taken fromthe blanket which will reveal thecharacteristic sh ape of this woodfiber. (Figure 5)


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Fibers Print interference caused by a fiber which is adh eredto the blanket or plate.

Occasionally the print can bedisrupted by Fibers which havecontaminated the system.There are three comm on types offibers which can be a cause ofspecks:1) Wood Cellulose - from paper orkraft cartons2) Cotto/7-from dampening rollersand rags3) Synthetic-irom fabric an dhickey rollers and fountainroller sleevesIn general, fibers are water receptiveand reject ink. These fibrous materialswill adhere to the blanket or plate andaccept water but will not take on anyink, and will therefore cause a spe ckin the print in the form of its ownshape. (Figure 1)By retrieving the fibrous material, thetape pull can be e xamined to identifythe type of fiber a nd then possiblydetermine its source.

50x

14


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Tape pull of paper fibers through a loupe....and how paper fibers appear at highermagnification.

Tape pull of cotton fibers through a loupe.... and how cotton fibers appear at highermagnification.

Tape pull of synthetic fibers through a loupe.... and how synthetic fibers appear at highermagnification.White Paper Tape Pull

2 Cellulose

12x

Wood Cellulose:If the fibers are cellulose paper fiber(Figure 2), the sheets should becheck ed for poss ible fiber dust. Thiscan be done by shining a low anglelight (Note: See photo Figure 2 onpage 18) across the unprinted sheetin the lift. If no loose su rface dust isfound, look through the printed sheeto find the original sheet upon whichthe defect begins, and look forpossible fiber picking.Cotton:If the fibers are cotton (Figure 3), theis a possibility that a portion of acleaning rag could have been caughin the press, and the remnants havecontaminated the ink. The ink fountaishould be washed up and fresh inkplaced in the fountain.It is comm on practice in thepressrooms to use rags as "dams"to control the flow of ink to the rollersand rag fragmen ts m ay break away.Synthetic:If the fibers are synth etic (Figure 4),they may have two possible sou rcesAs above, a synthetic rag cou ldhave contam inated the system, or thplastic bristles from a hickey-pickerroller could be breaking apart.

4 Synthetic

12x


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Pits Pit in plate.A pit in the surface of an offset plate before inking.

The same pit in the plate after inking.

Pits may be described as indentationsor wells in the surface of the plate orpaper.PlatesPits in a Plate cause specks inprinting because the ink form rollerscannot apply ink down into the pits.(Figure 1)The result is a white spec k in theprinted im age. (Figures 2 and 3)It is relatively easy to determinethe origin ofa pit. In the plate, theywill repeat on the printed sheets ina regular pattern. Sometimes thesecan be correc ted on press by thepressperson filling in the hole. % + * +Btttt ft

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Pit in paper.

A pit in the surface of paper before printing. White PaperThe same pit in the paper after printing.

4 Papei PaperPits in Paper cause specks in printibecause the blanket cannot app ly indown into the bottom of the p it.(Figure 4)The result is a white spec k in theprinted image due to the pit notreceiving any ink. (Figures 5 and 6)Pits in Paper are most commonlyfound in cast coated p apers, due totheir man ufacturing pro cess, and wiloccur randomly throughout theprinted image.Replacing the paper is the only suremethod of eliminating these spec ksfrom the p rinted job.


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Dust Paper dust collecting on the 1st printing blanket.Using a low angle light to look for dust particles onthe surface of the white paper (inset).

A printed halftone with paper dust specks.

Loose Surface Dust on pape r is acommon cause of specks in printing.Dust is most likely deposited on thesheets during sheeting, cutting andtrimming operations and can becomposed of both fiber and coatingmaterials that have been fragmen tedfrom the edges.Once in the pressroom duringstacking and feeding the dust canwork its way towards the center of thesheet and interfere with the imagearea.When the loose dust sets on thepaper's su rface, it prevents the inkfrom reaching the sheet and s ticks tothe blanket. (Figure 1)As the dust collec ts on the blanket, itwill pick up ink and then print as darkspecks in printing.


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How the coating will fracture at the beveled edge ofthe blade.

A rough cut from a dull slitter wheel w ill generatedust.

Rough cut from the beveled edge o f the trimmerblade on coated cover.

Smooth cut from the back edge of the trimmer bladeon coated cover.

Information Original White PaperSape Pull

Paper trimm ed by the back of thecutter knife will have clean edg es.Paper edges cut by the beveled sideof the knife will show dust and paperparticles. All cuts should be plannedto permit those edge s facing thebeveled side of the knife to beretrimmed with the ba ck ed ge of theknife.The trimm ing a nd s litting wheels onthe mill's finishing eq uipment cancreate a rough cut which maygenerate excess dust.The photographs to the right showthe effect of paper cut by the beveledside of the knife (Figure 6) versuspaper retrimmed by the back of theknife (Figure 7).

Proper Trimm ingThe necessary trimm ing of paperdislodges some of the fibers andpigme nts co ntained in it. Dust in theair will settle on exposed sheets ofpaper in mills and in pressrooms.Dust and fiber particles canaccum ulate on the press deliverysystems and d rop onto sheets thatwere spotless when they entered thepress. Spray-fogged pressrooms arealso a major source of dirt and dust.The first correc tive m easure is to try adifferent lot of paper.The best precautionary m easures are1) Maintain a general cleanlinessin the pressroom.2) Keep cutting knives sharp.3) Back-trim all coated pap ers cutdown from a mill size and wipewith a black velvet rag beforeprinting.

5*

1


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WaterInterference Ink and fountain solution mixing.

In both sheet fed and web printing,the interaction of ink, fountain solutionand paper must be kept in properbalance or a printing d efect will occurwhich is comm only referred to asWater Interference.Water Interference manifests itself aswhite specks in printing, and canoriginate from three different source s:

/n/c-Water Emulsification* RatesPaper- Receptivity to W aterFountain Solution -Wettabil i ty

20

*There are some arguments as to whether a truewater and ink emulsion is attained in offset printinFor the purpose of this discussion, we will be usinthe term "Emulsification" to describe ink andfountain solution mixing.


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The three characteristic water pick-up curves of ink,according to Surland. (Sun Chemical Corp.)

Time

Ink & Water EmulsificationAn offset ink is formulated to pick upand emulsify an amount of "water"that will:1) Allow the ink and plate to print asharp dot with minimal dot gain.2) Allow a quantity of fountainsolution to be run on presswhich will keep the non-imageareas of the plate running cleanand free of scum ming andtinting.3) Allow the ink to remain"lubricated" to run through themultiple units on a printingpress.4) Allow the ink to release thewater for proper drying in thesheet fed lifts, or in the web

ovens.According to Surland (Sun ChemicalCorp .), inks have three (3)characteristic water emulsificationcurves. (Figure 2)Ink #1 continually picks up water.Ink # 2 has what has been describedas an "idea l" curve in that it picks up avolume of water initially, reac hesequilibrium, and can print a sharp dotInk # 3 lacks the ability to pickupwater. This ink will carry e xces s w ateron its surface and can result in WaterInterference.

2


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Ink # 2 which picks up the "ideal" amount of water.How Ink # 2 prints.Ink # 3 which lacks the ability to pick up water.How Ink # 3 prints.

Ink's Effect in W aterInterferenceSince the ink and water hit the papersimultaneously in the image area,the paper m ust have the capacity toaccept both ink and water.Diagram 3 depicts Ink #2 which picksup the ideal amo unt of water. This inkwill carry water to the p aper on itssurface as well as water em ulsified init. This ink should p roduce a dot whichis sharp and clear.If the p aper cannot acc ept water, or ifthe ink is carryin g an e xcess of water,then the result will be white speckswhere the water hits the p aper first,and the ink will not transfer.Diagram 4 depicts Ink #3 which lacksthe ability to pick up water. Inste ad, itcarries too much "free" water on itssurface and, when printed, results inbroken dots and the appearanc e ofwhite specks in the printed image.

P w w ^ P W 4P *Pr ^ P

P ^ P ! ^F ^ r ^ P ^ P

22


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Diagram showing how the fountain solution onthe non-image area from the 1st printing unit caninterfere with the transfer of the ink in the 2ndprinting unit.Information Ink: Can Ink: Fountain

Plate

1st UnitBlanket

2nd UnitBlanket

Paper

Paper's Effect in WaterInterferenceWhen the ink and water balance onpress is normal, water interferencecan still occur if the paper is toowater tight.That is, the water in the non-imagearea from a previous printing unit canremain in excess on the paper'ssurface, and then interfere with thetransfer of the subsequent colors.Figure 5 above demonstrates how thenon-image area from the 1st printingunit (black) can remain on the surfaceof a water tight sheet and causespecks in the 2nd unit (cyan) print.Running minimum fountain solution orincreased isopropyl alcohol canminimize this prob lem, and running adifferent, more "water receptive"stock can often eliminate it.


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Piling Ink and paper m aterial building on the blanket'ssurface.A portion of the ink roller train of a magenta printingunit.

A sample of fountain solution being removed fromthe circulation tank of a press.

Piling is a build-up of ink and/or papermaterial on the blanket during printing.(Figure 1)There are 3 comm on types of piling:

Image Area Paper PilingImage Area Ink PilingNon-Image Area PilingIn both sheet-fed and web offsetprinting, the ink film can lose itsvolatile materials as it passes throughthe printing units on the press. If theink film reaches a "critical state" whilethe pa per is still in the press, the inkmay lift off (image area ink piling) fromthe sheet, or the tack of the ink canpull the fibers and/or coating from thesheet (image area paper piling).

An ink can lose these volatile, thin oilsin the following w ays: In the Ink Train (Figure 2) a verythin film of ink can have prolongedexposure to the air. This can occu rduring a long makeready, or whenrunning a light coverage form. When Fountain So lution (Figure 3)is ad de d, the ink's ability to retainits thin oils may cha nge . On the Plate, an even thinner inkfilm is again ex pose d to the airwhile being mixed with the fountain solution. The surface of the Blanket canabsorb these thin oils from theink film. Blankets vary in their oilabsorbency characteristics. When the ink film is printed ontothe Paper, and then passes throughmultiple printing units, the surface ofthe sheet absorbs these thin oilsfrom the ink film, and the printed filmagain contacts additional blanketsurfaces.

24


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The first down ink builds tack as it proceeds throughthe press, and cause s coating pick on the last unit.

An ink which has lost its lubrication will split back tothe blanket's surface.

Image Area Paper P ilingIf the tack of the ink film has in creas edas it lost its volatile material, its"printing tack" may be considerablygreater than its "c an " tack. Thereforeit now has the a bility to pu ll up thepaper's surface and result in ink andpaper building up on the blanket'ssurface.This type of piling can occur moreseverely in the last units on the pressand at times may oc cur exclusivelyon the last printing unit. For examp le,the first down ink could be printed ata tack of 12 (at 800 rpm s, 90F). As

Information Ink: Can Ink: Fountain Original

E Hhite Paper Tape Pull FountainSolutionthe ink film builds tack on the paperand reaches the fourth printing unit,its printing tack may now be 18,which is high enough to pick thepaper. This type of piling has beencommonly called Carry-Over Piling.(Figure 4)Possible corrective measures wouldbe: Reduce the tack of the ink. Addtransparent white to the ink to reduceits color strength. (Running a thickerfilm should lower the printing tack,but a caution to watch dot gain.)Replace the paper. Replace the inkwith a slower setting formulation.

No n-Imag e Area PilingOccasionally ink, paper and fountainsolution material will build up onthe blanket in the non-image areas.This defect, seen most often in weboffset printing, is not fully understoodand can be removed by frequentwashups. It was not docum ented forthis pu blication.

Fibers

Image A rea Ink PilingIf the ink film has lost a qu antity ofits thin oil and has beco me a "so ft"and "d oug hy" material, and lost itslubrication properties it will nottransfer to the paper p roperly andwill build up on the blanket.(Figures)Corrective measures would be: toadd petroleum/mineral oil to the ink(V2-I oz. per pound) to improve itslubrication, chec k the fountainsolution to assure that minimum etchis present,* or try a new b atch of ink.

*Check Glossary for comments on pH an dconductivity.2


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Spray on blanket.

Tape pull from blanket.

Scanning E lectron photo of tape pull.

Press sheet with voids caused from excess spray.mSpray particles that caused the voids in Figure 9 arestuck to the opposite sheet.

Scanning Electron photos of Figure 8 (left) andFigure 9 (right).

ggInformation Original Tape Pull

^ .

20:

Here are two exam ples of howrunning too much spray can causespecks in printing:1) Too much spray when runningthe first printing pass: This can resultin the spray transferring onto theunprinted side of the sheet above.This spray can then contaminate theprint during the second pass, andcreate voids where the ink beingprinted canno t con tact the sheet. Thispray will build up on the blanket(Figure 5) and can be removed usingtape pull material for verification(Figures 6 a nd 7). The lift of shee tsmay have to be blanked through abare blanket unit to remove the sp raybefore the second side can beprinted.2) Too much spray when printing thsecond side: This can result in thespray particles from the second sidebeing imb edde d in or sticking tothe ink which was printed on the firstside. Because these sheets are nowblock ed together, when they areseparated in the bind ery the sprayparticles can pull ink and papermaterial away from the su rface,leaving white voids in the print (Figure8). Close examination will show thatthe materials which caused the voidon one sheet will be attac hed to thesheet above it. (Figure 9)The photos in Figure 10 are S.E.M.photomicrographs of Figures 8 and 9The photo on the left shows the voidsin the sheet from Figure 8 and thephoto on the right shows the particlewhich left the void stuck to the sheetabove as in Figure 9.

50 x 2


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WarrenPaperMerchants

AlabamaBirminghamHuntsvilleMobile

AlaskaAnchorageArizonaPhoenixTucsonArkansasLittle RockCaliforniaFresnoLos AngelesSacramentoSan DiegoSan FranciscoColoradoColorado SpringsDenver

Grand JunctionPuebloConnecticutHartfordNew Haven

Dillard Paper Co.Sloan Paper Co.Sloan Paper Co.Strickland Paper Co.Unijax, Inc.

Zellerbach Paper Co.

Zellerbach Paper Co.Zellerbach Paper Co.

Western Paper Co.

Zellerbach Paper Co.LaSalle Paper Co.Zellerbach Paper Co.Zellerbach Paper Co.Zellerbach Paper Co.Zellerbach Paper Co.

Dixon Paper Co.Carpenter Paper Co.Dixon Paper Co.Zellerbach Paper Co.Dixon Paper Co.Dixon Paper Co.Carter RiceLindenmeyr Paper CorpCarter Rice

District of ColumbiaWashington Stanford Paper Co.

Virginia Paper Co.FloridaJacksonvilleMiamiOrlandoTampa

Palmer Paper Co.Virgina Paper Co.Palmer Paper Co.Virginia Paper Co.Palmer Paper Co.Virginia Paper Co.Palmer Paper Co.Virginia Paper Co.

GeorgiaAtlantaAugustaColumbusMaconRomeHawaiiHonolulu

IdahoBoise

IllinoisChampaignChicago

PeoriaRock Island

Dillard Paper Co.Sloan Paper Co.Dillard Paper Co.Sloan Paper Co.Dillard Paper Co.Dillard Paper Co.

HOPACOZellerbach Paper Co.

Dixon Paper Co.Zellerbach Paper Co.

Crescent Paper Co.Bradner Smith & Co .Leslie/Chicago Paper Div.Hobart/Mclntosh Paper Co.LaSalle Messinger Paper Co.Marquette/Jim Walter PapersMidland Paper Co.Tobey Peoria Paper Co.Leslie Paper

Massachusetts

IndianaFort WayneIndianapolisSouth BendIowaCedar RapidsDes MoinesSioux CityKansasTopekaWichitaKentuckyLexingtonLouisville

LouisianaBaton RougeLafayetteNew OrleansShreveport

MainePortlandMarylandBaltimoreSavage

Taylor Martin PapersCrescent Paper Co.Ris Paper Co., Inc.Ris Paper Co ., Inc.

Midwestern Paper Co.Leslie PaperMidwestern Paper Co.Midwestern Paper Co.

Midwestern Paper Co.Western Paper Co.

Athens Paper Co.Athens Paper Co.Louisvil le/Southeastern Paper Co.

Butler PaperButler PaperPalmer Paper Co.Unijax, Inc.Butler PaperWestern Paper Co.

Carter RiceC.H. Robinson Co.

Baltimore-Warner Paper Co.Butler PaperWilcox, Walter Furlong Paper Co.

Boston

SpringfieldWoburnWorcesterMichiganDetroitGrand RapidsLansingSaginawMinnesotaMinneapolisSt. PaulMississippiJacksonMissouriKansas CitySt. Louis

SpringfieldMontanaBillingsGreat FallsNebraskaLincolnOmaha

NevadaLas VegasRenoNew HampshConcordNew JerseyEast RutherfordNewarkRutherfordTrenton

Carter RiceThe Century Paper Co., Inc.Lindenmeyr Paper Corp.Carter RiceC.H. Robinson Co.Carter Rice

Chope-Union Paper Co.Seaman-Patrick Paper Co.Carpenter Paper Co.Quimby-Walstrom Paper Co.Copco Papers/Dudley DivisionCopco Papers/Dudley D ivision

Leslie PaperInter-City Paper Co.

Sloan Paper Co.

Midwestern Paper Co.Tobey Fine PapersDistribix, Inc.Shaughnessy-Kniep-Hawe Paper CoTobey Fine PapersMidwestern Paper Co.


Carpenter Paper Co.Western Paper Co.Carpenter Paper Co.Western Paper Co.

LaSalle Paper Co.Zellerbach Paper Co.Zellerbach Paper Co.

ireCarter RiceBulkley DuntonCentral Paper Co.Lindenmeyr Paper Corp.Central Paper Co.

New MexicoAlbuquerque Dixon Paper Co.

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New YorkAlbanyBinghamtonBuffaloNew York City

RochesterSyracuseUticaNorth CarolCharlotte

FayettevilleGreensboroRaleighWilmingtonWinston-SalemOhioCincinnatiClevelandColumbusCuyahoga FallsDayton

Hudson Valley Paper Co.Hudson Valley Paper Co.Seneca Paper Co.Ail ing and CorySeneca Paper Co.Ail ing and CoryBaldwin Paper Co.Bulkley DuntonLindenmeyr Paper Corp.Marquardt & Co., Inc.Ail ing and CorySeneca Paper Co.Ail ing and CorySeneca Paper Co.Ail ing and Cory

naCaskie Paper Co., Inc.Dillard Paper Co.Virginia Paper Co.Caskie Paper Co., Inc.Dillard Paper Co.Virginia Paper Co.Dillard Paper Co.Virginia Paper Co.Dillard Paper Co.Dil lard Paper C o.

Nationwide PapersRis Paper Co., Inc.Ail ing and CoryMillcraft Paper Co.Cordage Papers/Columbus DivisionMillcraft Paper Co.Ris Paper Co., Inc.Toledo Commerce Paper Co.

OklahomaOklahoma City Western Paper Co.Tulsa Mead Merchants

Western Paper Co.OregonPortlandPennsylvaniaAllentownErieHarrisburgLancasterPhiladelphia

Zellerbach Paper Co.3

Ailing and CoryAil ing and CoryAil ing and CoryLindenmeyr Paper Corp.Ail ing and CoryLindenmeyr Paper Corp.Ail ing and CoryAil ing and CoryPittsburghScranton

Rhode IslandPawtucket Carter RiceRumford The Rourke-Eno Paper Co., Inc.South CarolinaCharleston Dil lard Paper Co.Columbia Dil lard Paper Co.

Virginia Paper Co.Greenvil le Caskie Paper Co., Inc.

Dil lard Paper Co.

TennesseeChattanoogaKnoxvilleMemphisNashville

TexasAmarilloAustinDallasEl PasoFort WorthHoustonLubbockSan AntonioWacoUtahSalt Lake City

VermontBurlingtonVirginiaBristolLynchburgNorfolkRichmondRoanoke

Sloan Paper Co.Dillard Paper Co.Western Paper Co.Athens PaperCordage P apers/Nashville Div.Sloan Paper Co.

Dixon Paper Co.Monarch Paper Co.Olmsted-Kirk Paper Co.Monarch Paper Co.Olmsted-Kirk Paper Co.Dixon Paper Co.Monarch Paper Co.Olmsted-Kirk Paper Co.Monarch Paper Co.Olmsted-Kirk Paper Co.Dixon Paper Co.Monarch Paper Co.Olmsted-Kirk Paper Co.


Hudson Valley Paper Co.

Dillard Paper Co.Caskie Paper Co., Inc.Dillard Paper Co.Dillard Paper Co.Dillard Paper Co.Virginia Paper Co.Dillard Paper Co.

Virginia Beach Virginia Paper Co.WashingtonSeattleSpokane

Zellerbach Paper Co.Zellerbach Paper Co.

Export and ForeignNew York, N.Y.Canada

CalgaryEdmontonMontrealOttawaReginaSaskatoonTorontoVancouverWinnipeg

AustraliaNew Zealand

Mo l l e r&RotheJnc .Barber-Ell isBarber-Ell isLes papiers graphiquesLauzier Little, Inc.Buntin Reid PaperBarber-Ell isBarber-Ell isBuntin Reid PaperGraphic PapersBarber-Ell isBarber-Ell isEdwards Dunlop and B .J. BallB.J. Ball (N.Z.) Ltd.

West VirginiaHuntington Cordage Papers/Huntington DivisionWisconsinAppletonMadisonMilwaukeeNew Berlin

Universal Paper Corp.Universal Paper Corp.Hobart/Mclntosh-Bouer Div.Reliable Paper Co.Universal Paper Corp.

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Cleer Adheer laminating sheets,manufactured by C-line Corporation,are available through most localstationery and office supply stores.

Printed in U.S.A. on Lustro Gloss 100 lb and Lustro Gloss C over 100 lb 1988, S.D. Warren Com pany, a Subsidiary of Scott Paper Com pany


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S.D. Warren Company,A Subsid iary o f Scott Paper CompanyBoston , Mas sachuse t ts 02110

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