sten screen printing

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A project of Volunteers in AsiaThe Sten- Screen: Maki ng and Usi ng a Low- CostI - J r i nti ngrocessby I an McLarenPublished by:Intermediate Technology Development Group (ITDG)

Available from:Intermediate Technology Publications9 King StreetLondon WCZE 8HNENGLAND

Reproduced by permission.Reproduction of this microfiche document in anyform is subj ect to the same restrictions as thoseof the original document.


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The S&n-screenMakhg and using abw-cost printing processIan Mclaren


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THE STEN-SCREEN PRINTER

A manual on how to produce and mea low cost printing device

Ian McLaren

@ Intermediate Technology Publications Ltd.1983


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I- General descriptionThe Sten-Screen rocess is a hyb,-idduplicating nd printing echnique.Basically t combines tencil dupli-cator stencils ith the screen pro-cess. This enables one to createlegible and compact printed Inat;ter,using equipdent hich one can makeoneself out of readily availableitems. The procless oes not requireelectricity.These instructions ive gjlidancenhow to build and use the equipment.The screen uses a simple rectangularframe with textile tretched crossit. This is used as a support forstencil duplicator tencils. hetext and images hich are requiredto bz reproduced ay be eithertyped, handwritten r drawn uponthese.(One ay also reproduce hoto-graphs: details re given in Section4.7)

If one wishes to print two or morepages simultaneously ne simplyfixes the corresponding umber ofstencils o the underside f thescreen.Because it is a form of screen pro-cess printing ne may print onto alarge sheet. If the intention s toproduce posters the sheet will beleft unfolded. Alternatively nemay fold the sheet to produce new-paper or booklet formats.The process may also be developed oprint onto materials ther thanpaper eg cloth, plastics, tc.Our drawing shows the basic elementsof the process,

Fabric


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PREFACEThe Sten-Screen rinting process asdeveloped o produce simple lowcost printing echnique hichfulfills he following riteria:- it can produce egible nd compacttext- it does not require electricity orun- it can be made from locallyavailable aterials- it can print on a variety fmaterials part from paper

- it can be easily operated ithoutthe aid of sophisticated quipmentEssentially, he Sten-screen rocessis a combination f a screen processpress ith stencil uplicatingstencils for the production f theoriginal ext and imagery.Following UNESCO funded study onlow cost printing echniques nwhich the Sten-screen as firstmentioned, ntermedgate echnologyIndustrial ervices provided undingfor the development nd fieldtesting of the process. The fieldtesting as conducted n threeAfrican countries, enya, anzaniaand Zimbabwe, uring the summer of1982. Kenya and Tanzania ade theirown equipment rom the originaldraft of this manual, and a readymade up unit was sent to Zimbabwefor demonstration t the RuralTechnology evelopment air.Inevitably, here were variations nthe results f the device from thevarious locations, ut the reactionsin all cases were very positive ndencouraging.As a result, t wasdecided to publish this modifiedversion of the original anual.


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The screen should be built fromseasoned imber, preferably ardwood(1). A smooth baseboard s essent-ial; this is best made from block-board, marine ply, or hardwood.The equipment an be used to printeither a single page individually yusing a single stencil:or f a largenumber of copies are required, necan reduce the labour of printing ymaking duplicate tencils. If onedoes this one can print two or morecopies simultaneously y mountingthe duPLicate tencils nto thescreen. The process Is probablybest suited to this type of work.Alternatively ne may print a docu-ment with a number of pages using asingle pass of the press by mountingthe appropriate umber of stencilsonto the screen. Sections . 3 and4.4.give urther uidance n this.1) Ha&wood i: recommended ecause3ne uses liquid generous: whe.awashing the equipment fter use.This may cause softwood o warp;which will make it difficult oprint effectively. If you have onlysoftwod available nd wish to pro-long the life of the screen then itmight be worthwhile iving it eithera protective oating f sealer, orimpregnating he timber. However,we do r,ot now whether there islikely to be any reaction etweenthe protective edium and whateverink you may use.In industrial pplications hescreen is made from rectangular ec-tion stainless teel tube. An Alsized screen of this type costs E23in the UK, plus fabric. If you canget something uitable ade up bearin mind that you will require asophisticated ethod of fixing thefabric to the screen if the correcttension is to be maintained. We canprovide details of this.

To make the press you will requireScreenTo print an A2 sheet (594 : 42Omm,33 113 : 23 3/ 8") .

- Timberapproximately 5 : 45ma ex 2 : 2")two lengths, ach of approximately2m (6' 7") and 1.4m (4' gtl).

- Dowel (arid lue) or screws to jointhe timber- Fabric(organdie, ayon, nylon or silk)to act as a support for thestencil- Hingesto join the screen to thebaseboard.75mm (3"), rising butts are bestfor this p~rspose, ee se&ion 2.4- Battensfor extra tightening f the screen.(see Section 2.3) and for spacingapart the screen and baseboard(see Section 2.4). You will needa total of 6 pieces, ll approxi-mately 5mm (3/ 16"i thick.4 lengths pproximately 5Ormu

(2' 9 l / 2")2 lengths pproximately OO1mn(1' 11 l / 2")

BaseboardTo act as a smooth surface n which toprint.- Plywood or blockboard

1 : 0, 8m (3' 4" : 2' 8")SqueegeeTo press the ink through the StenCil- Offcuts of timber, n old ruler,or some other similar moothmaterial.traightToolsYou will also require the following

- Carpenters aw- Wood drill, to suit the dowels- 4 carpentry clamps


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- Scissors- Hammer and 12mm ('/2") ta-.-%, rstaple gun- Screwdriver- BradawlTo prepare the stencilyou will require:

Something ith which to create themaster on the stencil.A typewriter or lengthy text,and/or a pointed tool such as adried-up iro (or needle), f youwish to write by hand or makedrawings. (Section .1)Waterto help stretch he stencilssmoothly nto the screen: (Sec-tion 3.2) and also to clean upwith after-wards. (Section )A clothes line and clothes pegs(or string and paperclips) o hangthe printed copies upon when dry-ing. Alternatively ou can use adrying rack, if you can get holdof one. (Section .3)Rags, and maybe a sponge.(Sections .2 and 4.7)Gumstrip(paper ape with a water solubleadhesive n one side - the widerthe tape the better for some uses)for fixing the stencil (s) to thescreen. (Section .2)

When printing you will require:Something o print upon of theappropriate ize. If you usepaper, the more absorbent t isthe better. A glazed surface islikely to take longer to dry andthis can be troublesome f youhave a lot of wet copies flappingaround. If you wish to make morerobust copies you may also printby Sten-screen nto cloth, plasticand other materials.An overrall r working clothesA minimum space of 2.4 : 1.2m (8 :4')A work surface the size of astandard oorInkstencil uplicator nk is adequateAs little wind as possible!You will also need a calm method-ical working atmosphere. It willprobably e helpful to have some-one to assist you; children eemto enjoy taking part in this acti-vity.

After printing ou will require- Plenty of rags- WaterIt is important o clean thescreen thoroughly s soon as youfinish printing. (Section .7)If you have a short length of hoseavailable (say 2m - 6') which youcan fix to a tap, this will makecleaning uch quicker nd moreeffective.

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2 - Making e screenYou may decide to use a professionalcarpenter, r someone ith better woodworking skills than you have yourself.The jointing ethod suggested ere issuitable or someone ith only modestcarpentry bility. A professionalcarpenter ay prefer to use somethicgmore elegant. The precise way inwhich one makes the frame is notsignificant: ut it is important hatthe screen is flat, ie that it doesnot 'rock' hen in contact ith thebaseboard.2.1 Cot the timber to sizeThese instructions nable one to builda screen which will print an A2 sheet(594 : 42Omm 23 3/8 : 16 l / 2") . Thescreen is larger than the printedsheet to give one extra room whenprinting. The amount of this extraspace is a matter of personal re-ference, ou may after trying thesesuggestions ecide that you need toallow a little more.Assuming you accept the dimensions esuggest here (and use 45 : 45mm / ex 2: 2" wood) you will require fourlengths f timber, two each of approx-imately m and 1.2m (6' 7" and 3' 11") .Ideally the timber should be cedar orrahmin, seasoned oftwood s OK butbear in mind our comments n Section1.Our drawing shows the required nter-nal dimensions; epending pon theze of timber you use this willaffect the overall xternal imen-sions.2.2 Joining the TimberDrill the jointsClamp the timber in place and drill(preferable wo) holes per joint. Onemay use either screws or dowels asfixings. If you choose to employscrews proceed to Section 2.3 - butbear in mind that it is best to usecountersunk crews. Cut the dowels tothe right length.Glue the JointsInsert the dowels; and when the gluehas dried, smooth off any surplusdowel or hardened lue (this may snagthe material hich you will be using

NB This drawing specifies nternaldimensions n millimetres.


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It is important hat the timber issmooth where it will come in contactwith the fabric; therwise he fabricmay tearras it is stretched ight.Use a flat file or sandpaper o smoothall of the undersides nd round offall edges and corners.2.3 Stretching he FabricThis is probably he most difficult& of the business f making thescreen. It can probably nly be doneby an adult. You need strong fingersif working on your oun - or one personto pull the fabric and a second tosecure it.Lay the fabric out and place thescreen on top of it. Cut out of thefabric to allow extra so that you willbe able to wrap the fabric over theframe.Fix the fabric to the frame witheither staples or tacks.It is important hat the fabric isnice and taut. (As a guide, it shouldbe sufficiently aut that a smalllight object such as a coin willbounce if dropped nto it from approx-imately 300x01 12").The best way to obtain the correctdegree of tension s to start alongone of the long sides. Spread thefabric evenly along the sides of theframe and tack it at approximately701~~42314") ntervals. It is a goodidea at this stage not to drive thetacks home fully, asyou m?y wish toremove them as the fabric becomestighter. Once you have done thisrepeat the process on the opposite(long) side. Having made a pre-liminary ixing in this way, pull thefabric as tight as you can over theedge of the frame and double the num-ber of tacks (or staples). You mayfind that as the fabric tightens ouwill need to change the position fthe first row of tacks. If you findthat the fabric is insufficiently autafter fixing, ou can increase hetension y pushing thin bits of card-board or wooden battens pproximately51mt 31169, between the frame and thefabric. Similarly, f you use a nat-ural fabric for the screen, and thistends to give with use; you can usethis technique o increase he ten-sion5 -.


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You are likely to find that afterusing the screen several times itbecomes orn or clogs in places withdried ink or other wastes. When thishappens you will have to take off thefabric and stretch ew material ontothe frame.2.4 Hingeing the Screen and BaseboardWe mentioned n Section 1 that youneed to print onto a smooth flat sur-face if you are to obtain legibleresults. Also, when printing you willneed to position he screen accuratel yonto the paper.To do this you need a baseboard utfrom a sheet of smooth flat wood (suchas chipboard r plywood). This shouldbe a little larger than the screen,which should be joined to the base-board with a pair of hinges. It isbest to usa rising butt hinges, sothat you can remove the screen easi l yfrom the baseboard hen you have fin-ished printing. If you have nothingto hand, a hinge can be improvised ysimply nailing a bit of textile orleather o both the screen and base-board. B&ore you fix the hinges seeSection 4.1. '2.5 Supporting he ScreenWhile printing ou will be continu-ously loading and unloading heets ofpaper between the screen and base-board. It is useful (though otessential) o be able to prop thescreen up temporarily or this pur-pose. A simple light piece of wood issufficient o act as a prop andscreen. (An added 'touch' to pre-vent the prop getting in the way whenprinting ne can fit a hook and eye tokeep things tidy).Industrial creen printing ables usea counterbalance o that the screenrises automatically fter each impres-sion. Equipment f this type costs91,450 in the UK for an Al sizedsheet. You may be able to improvisecounterbalance.

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2.6 Making the "Squeegee"In Section 1 we mentioned hat the inkis forced through the stencil by pass-ing a film of ink across the screen(once the stencil as been fixed toit).To obtain a consistent nd manageablefilm of ink one requires smoothstraight lade of some sort. Con-ventional creen processs rinters sea rubber blade approximately Inan(l/4") thick mounted in a woodenhandle. This tool has the wonderfulname "squeegee". We rind that onedoes not require a professionalsqueegee o obtain adequate esults;and have improvised ne by sandwichingan old plastic ruler or piece of per-spex between two bits of wood. Thissuggests hat any smooth straight dgewhich has a little "give" in it willprobably e OK.Once you have your;- screen- baseboard nd- squeegeeyou have a wprinting ress"!


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3 - Using the screen3. 1 Prepare the Stencil(s)Once you have a screen and the otherimcillarieS you are in a position ostart print production.Assuming you have a clear idea of whatyou wish to print; for example to whomyour message is addressed; he form itshould take (the written style, mix ofwords and illustrations, tc); thenumber of copies required; nd havethe necessary upplies f paper andink - then you are in a position ostart preparing he stencil(s).Although ne can draw and write ontothe stencils using a dried out biroor similar tool) the best way to com-press text so that it is compact butstill legible, s to use a typewriter.If you have a choice of sizes oralphabet, ntil you have someexperience f the Sten-screen rocessit is probably est to use a type-writer with a larger size. Tencharacters o the inch (often nown as"pica") is preferable. Bear in mindthat the ink is likely to spread whenprinted, o if you have a choice ofstyle of alphabet t is best to chooseone where the shapes are "open". ythis we mean a design where the inter-ior forms of the letters (such aso,e,a,m, tc.1 are as large aspossible.Prepare the stencils n the same wayas you would if you were using a sten-cil duplicator. You will find supple-mentary advice in Section 4 on how tocombine individual tencils o thatyou may make full use of the potentialof the Sten-screen rocess to minimisethe labour of printing.If you require text which is largerthan a typewriter an produce you caneither handwrite his, or if one isavailable, se a (drawing) tencil.These are used for a variety of diffe-rent purposes ncluding:technical rawing, griculture(forestry); nd despatch (where theyare used for labelling acking cases);as well as signwriting.


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3.2 Stretch the Prepared tencilonto the ScreenOnce you have prepared the necessarystencils, hese have to be mountedonto the screen. It is important hatthey are bonded evenly, ithout anywrinkles n the image making srea.(If not, the final copies will dupli-cate faithfully hese irregularities).The best way to ensure an even contactbetween he stencil nd the screen isto wet the screen fairly generously;and to spread the stencil onto the;zreen ith a damp cloth or sponge.It is particularly mportant o dothis ir hot climates, therwise oumay rind that the glue will dr beforea good bond is obtained.Note: It is essential hat you mountthe stencil n the underside f thescreen. The easiest ay to do this isto simply turn the screen upside downand fix one of the short sides of thestencil to the screen with dampenedgumstrip. (1) The stencils hould bemounted facedown.It is helpful to draw guidelines nthe screen for mounting the stencils.You can do this simply by drawing ntothe fabric with a 'soft' pencil (2B).If you first draw guidelines nto thebaseboard ou can trace these throughby laying the screen on the baseboard.Incidentally he guidlines n thebaseboard ill be useful later whenprinting for positioning he paper).It is also a good idea to number eachpage in the position equired, n boththe baseboard nd the screen. Then,when you turn the screen over to mountthe stencils ou will have a usefulguide for the correct location andorientation) f each stencil.Once you have one side taped intoposition, nd have smooothed he sten-cil down evenly, it is a simple matterto stick Me other sides down usingmore gumstrip.Having fixed the first stencil, ollowthe same procedure or the rest ofthem.When all of the stencils re in posi-tion it is necessary o mask off therest of Yhe creen completely, oprevent urplus ink from making every-thing messy. Masking is easily done,, _

usi ng either lots of gumstrip; r ifyou have a large area to cover, piecesof unused stencil stuck down withgumstrip. When you have completelymasked the screen check that there areno holes where the ink can sneakthrough, y holding the screen up tothe light. Cover any remaining oleswith patches of gumstrip.When the screen is neatly protectedstand it up to dry in a warm, wellventilated ocation (best out ofstrong sunlight).Once it is dry you are ready to print!

1) If gumstrip is not avai3able oucan use strips of practically nystrong non-absorbent aper and gluethese with a water soluble lue. Usewater soluble glue, otherwise ou willhave difficulty leaning he screenafter use. As we mentioned n Section1, once the screen becomes ermanentlyblocked ou will have to restretch t.You will rind further dvice inSection 4.7.


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3. 3 PrintingBefore you start printing t is wellworthwhile orting ut the workspaceinto clean nd dirty reas. Youwill probably rind that no matter howcarefully ou work, you will tend toget ink onto your fingers. Once thishappens it is easy for the printedmatter to become messy - as well aseverything lse you touch!It is helpful to have a second personto assist you, if only to hang theprinted heet up to dry. We find thatchildren rom twelve years old arecapable f assisting, nd even seem toenjoy the business f printing itself.The act of taking an impression oesnot require great strength r skill;older children re in our experiencecapable of this.Once you have prepared our workspace;and instilled n your assistant(s) heneed for a calm and methodical orkingatmosphere; tand the squeegee gainstthe inside of the screen.Place paper under the screen and posi-tion it, as described n Section 3. 4.Squeeze a ribbon of ink onto the

screen, etween the squeegee nd thestencil mage.Scrape the ink across the stencilwherever n image is required. Try tokeep the film of ink even. You willprobably se more ink than you re-quire Trial and error will demon-strate that you in fact require ur-prisingly ittle ink for it to pene-trate the fabric. Having made theimpression, ollect the ink togetherwith the squeegee efore you lift thescreen- try to keep the stencil freeof ink when lifting the screen.Having lifted the screen, remove theprinted opy; hang it up to dry; andload another sheet of paper.


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4 - Maintenance, Enhancements, Tips4.1 Fixing the HingesThe quality of the printed result isusually better if the fabric 'jumps*away from the paper as the squeegeepasses. This is known as the 'snapdistance'. It is easy to achieve hisif the screen is kept about 5mm(3/16") bove the paper. If you putsomething f this depth under thescreen when fixing the hinges thiswill automatically ive you the snapdistance or one side of the screen.Once the hinges are fixed in positionplace another spacer at the oppositeend of the screen and you will have ane;ren nap distance ver the fulllength of the screen.

with a single pass of the press. Withthis sized equipment ou can printnumerous ifferent ypes of publica-tion. You have the choice for exampleof printing ny of the following:- an 8 page bookletBy printing pages on each side ofthe sheet.- two copies of a 4 page bookletBy printing ll of the pages simultan-eously. Then once you have printedall the sheets on one side, turn theent&re supply over, rotate it through360 and continue rinting n thereverse f the sheet.

4.2 Alternative ized ScreensThese instructions re for the produc-tion of a screen suitable o prrnt anA2 sized sheet of paper. You can ofcourse make the screen to suit anysize 0r paper. We assume that youwill probably lso require ultimatelyother sized screens o suite Al and A3production.4.3 Formats obtainable rom an A2SheetWe have mentioned hat you can printitems with a large format, such asposters r wallcharts, y mountingseveral stencils nto the screen. Bydoing this you can obtain a printedimage o-rer he entire sheet. When youdo this you must bear in mind that thestencils re fixed to the screen withgumstrip which will not allow theink to penetrate. If your designrequires tencils o be joined youwill have to take account of this.(That is, you will have narrow bandsin the image whjch will not be capable0r printing). You can often camou-flage thlfs y adopting wmodularwdesign, such as this publication.Also, where you have large text runn-ing over two stencils, ou can usuallyarrange for the gumstrip to be stuckin the space betwee- the words.4.4 Printing Pages SimultaneouslyYou may find that the principal advan-tage of the Sten-screen rocess isthat you can print two or more pagessimultaneously.For example with anA2 screen you can print 4 pages of A4

To do this you will have to mount thestencils n the screen in the orderwhich is shown in the drawing.

- two copies of A3 sizeprinted ne sideBy making uplicate stencils ndmounting oth sets onto the samescreen.

- two copies of an A4 size,printed oth sidesBy making uplicate stencils gain,and printing oth sets simultaneously.In this case you should mount the


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stencils s indicated n the drawing.Having printed all the sheet simplyturn them over and print on the back -on this occasion ou do not need torotate the pile.

- four copies of an A4 size,printed n one side only.By making fouxuplicate sets of sten-cils and printing n the same way asthe previous xample.

4.5 Amounts 0r InkWhen spreading he ink over the screenfor the first time you will requiremuch more ink that you will subse-quently. Once you have a good film ofink over the area you require, henonly very little is needed to print.For example a single ribbon of inkfrom the tube will usually be suffi-cient for 4 or 5 copies. When print-ing it is best of pull the ink towardsyou; and to maintain firm and evenpressure. When printing he squeegeeshould be held at approximately 5 .4.6 PhotographsPreliminary rials suggest that if anelectronic tencil cutter is availablethis can be used to produce stencilsin the conventional ay, but to printthem by Sten-screen. If you decide toexperiment ith this you must ensurethat when the stencil as been cut

'open' or the ink to pass throughwith ease. To test the stencil simplyhold it up to the light. If lightshows through clearly, hen you shouldhave no difficulty rinting ith them.If the image is not clear enough, thenremake the stencil with a more con-trasty setting on the machine.Once you have an adequate tencil thenmount it in exactly the same way asdescribed n Section 3.2.4.7 Cleaning he ScreenWe said in Section 1 that the processdepends upon the ink passing throughthe fabric of the screen. It isobvious therefore hat if you wish toFe-use the screen you should keep itas clean as possible. This is notdifficult f you clean up as youfinish printing. Stencil duplicatorinks are soluble ith white spirit,you do not require specialist leaningfluids.Start the cleaning y wiping up mostof the surplus ink onto scrap paper.When most of the ink is off, you canwash off the.stencil nd gumstrip ithwater. Use a hose for this, becauseif the supply is sufficient ou cansquirt a high pressure et at thefabric without damaging t: and thisis a good way of clearing aste matterfrom the fabric. Use the turps todissolve ny patches of ink whichremain,and for cleaning he screenfabric generally.Cleaning p is a messy business youwill need plenty of rags, a largewaste bin, and a generous upply ofwater.If you are scrupulous n the way inwhich you clean up, it is possible olift off the stencil - and if it isclean enough, you may be able to storeit and use it for a second edition atsome future time. You can also leavethe stencils n the screen and printfurther copies later, so long as youmop up most of the ink with paper.No matter how clean you keep thescreen, or how careful you are withit, ultimately t will need replacing.When this time comes follow the proce-dures outlined n Section 2.3

sten screen printing

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