| Audio-Visual Communication Handbook |
|Basic production Techniques|
For duplicating instructional material there are many techniques ranging from processes that make one copy at a time to elaborate printing processes that produce thousands of copies per hour. Four relatively inexpensive basic processes will be described here.
In transfer processes a dye Image is produced on a master sheet by typing, writing or drawing. This image is then transferred to consecutive paper copies with a hectograph or spirit duplicator. Several different color dyes can be used on the same master for multiple color work. Copies are inexpensive to produce and are reasonably durable although the image will bleach if exposed to bright sunlight for extended periods of time.
Transfer processes are suitable for inexpensive production of limited quantities of newsletters, leaflets, instruction sheets, or classroom assignments or tests. They are also ideal for producing prototype copies of leaflets or pamphlets. The inexpensive copies can be used for field testing with a sample of the audience before going into mass production.
With the Hectograph process, a dye image is prepared on a master sheet, transferred to a gelatin surface, and then transferred to the copies. Twenty to thirty good copies can be made on paper or cardboard. There are four basic steps in the process.
1. Preparing the transfer pad. To make a transfer pad, a flat pan, such as a cookie sheet, or a shallow wooden box is needed. The pan should be slightly larger than the copies to be made. Prepare the transfer compound by combining one box of unflavored gelatin and one pint of glycerin. The mixture is boiled for about seven minutes. Any scum is then skimmed from the surface, and the mixture is poured into the pan and allowed to set for about 24 hours. Other formulas for preparing transfer pads are included in Appendix 4. Inexpensive kits that include a pan and the gelatin compound can be purchased in many places.
2. Preparing the master. Using Hectograph ink or special Hectograph pencils, draw what is to be duplicated on a sheet of paper. A glazed or hard-surfaced paper works best. Soft papers, like newsprint, absorb too much dye. Hectograph inks are available commercially or can be made as described in Appendix 4.
Hectograph "carbons," which strictly speaking are not carbons at all, also can be used.
They are made of paper-coated materials with a waxy substance impregnated with aniline dye. The most common colors used are purple, blue, red, green and black. When using a "carbon", place it face down on the master paper and write, draw or type on the back of the "carbon." This will form an image on the master that is right reading. Hectograph ribbons are also available for typing directly onto the master sheet.
3. Transfer the image to the transfer pad. Prepare the gelatin surface by wiping gently with a wet sponge that has had the excess water squeezed out. When the surface is thoroughly dampened, smooth the master sheet, dye side down, on the transfer pad. In four to six minutes, the dye image will have transferred to the gelatin. Then, carefully remove the master
4. Making the copies. Smooth a sheet of copy paper over the image on the gelatin, allow to transfer for five to ten seconds, and remove carefully. Continue making copies. allowing increasing transfer time as successive copies are produced. Any paper can be used as copy paper, but glazed surface works best because less dye is absorbed by the paper fibers.
When the desired number of copies are completed, wipe the surface of the gelatin with the damp sponge and cover with a piece of paper. Don't use hot water, because the gelatin surface will melt. The remaining dye image will transfer partially to the paper and the rest will be absorbed in the gelatin. The following day it can be used for duplicating another master. The gelatin compound can be recooked to destroy the old image or to remove surface blemishes
Basically, spirit duplication is similar to hectograph but is a mechanical process employing a duplicating machine. It is faster and cleaner than hectograph. Over 100 copies can be made from one master sheet. To make copies, a master sheet is placed on the drum, image side out. the paper tray is loaded, alcohol and feed controls are turned on, and the drum is turned by a crank. Each time the drum revolves, a sheet of paper is picked up, dampened with alcohol, and pressed again the master to make a copy. The darkness of the copies can be controlled by regulating the flow of alcohol, the pressure of the copy paper against the master, and the speed of the machine. Specific instructions come with the machines; and, in most cases, are printed on the body of the machine or on one of the paper trays.
Preparation of masters for spirit duplicating is the same as for hectograph except for one important difference. The dye image must be wrong reading. Most masters for spirit duplication are made using "carbons." Place the master sheet on top of the carbon and write, type or draw on the master sheet. This produces a reverse-reading, dye image on the other side of the master sheet. When using hectograph ink or pencil, the image must be drawn in reverse.
There are several techniques that can be used to correct an error when preparing the master for either hectograph or spirit duplication. If, for example, extra letters or some unwanted materials have been typed on the master, they can be cut out with a razor blade or small scissors. Also, such errors can be covered with a small piece of thin tape. When an error needs to be corrected, use a razor blade to scrape off the dye image containing the error. Then, place a piece of unused "carbon" where the dye image has been scraped off (that is, where the error was), and type in the correction. Material that has been written or drawn on the master can be removed or corrected in the same manner.
The simplest method of stenciling involves cutting openings in a material such as oil stencil board, ordinary thin cardboard, wax paper or heavy wrapping paper, and brushing the ink or paint through the openings with a fairly dry stiff brush. A wet brush will allow the ink or paint to run under the edges of the openings. Stencil processes are limited to shapes or to large or bold letters because it is difficult to retain the center openings in letters such as A, B, D, O. P. Q. and R. The production of multiple copies is slow. More sophisticated stencil processes are stencil duplication and silk-screen printing.
Stencil duplication is more commonly known as mimeograph or cyclostyle. In this process a stencil is prepared on a thin, open-fibered paper coated with a waxy substance. Ink is forced through the stencil to print multiple copies on paper. Several thousand copies can be made from a stencil. Different colors can be used by making a separate stencil for each color and rerunning copies through the duplicating equipment. Stencil duplication is ideal for making newsletters, leaflets, pamphlets or small newspapers when the quantity needed is limited to a few thousand copies. Basically, stencil duplication is a two-step process.
1. Prepare the stencil. Place a stencil on a hard smooth surface. Type, write or draw with a ball point pen or stylus. Stencils are available commercially at varying prices. The better stencils will produce more and sharper copies. Detailed instructions for use come with each box of stencils. Electronic stencil cutters have been introduced in recent years that are ideal for making special stencils from drawings or combinations of drawings and typing. These are, however, expensive and not readily available.
2. Make the copies. Copies can be made using a simple silk screen, a portable duplicator, or a duplicating machine. Plans for making a portable duplicator are included in Appendix 5. To make copies with a simple screen or portable duplicator, the stencil is taped to the screen and a paste duplicating ink is rolled across the surface with a soft rubber roller. This produces satisfactory copies, but is slow. For improved quality and speed, a stencil duplicating machine is ideal. Such machines resemble a spirit duplicator in outward appearance but are quite different in operation. Specific instructions for attaching the stencil and running copies come with each machine.
The paper for making copies by stencil duplication must have a soft, porous surface that will absorb ink. Such paper is sold under various brand names. Stencils can be saved for re-use by placing them in a folder or newspaper or other soft paper.
The silk-screen process is an inexpensive, relatively simple printing method for producing posters, charts, signs, leaflet or booklet covers and similar materials. Printing can be on cheap paper, cardboard, cloth, plastic, wood or practically any other material. Multiple-colored images can be made by cutting separate stencils for different parts of a visual and printing each one with a different color paint.
All that is needed to do simple silk-screen printing is a silk-screen frame hinged to a plywood base, a squeegee, and a few readily available materials. Frames can be purchased ready to use from art supply stores or can be constructed following these general guides.
1. Construct a frame slightly larger than the largest poster you plan to make. Use pieces of hard wood about 1 1/4. inches square.
2. Cover the frame with silk, organdy or nylon. The cloth should be stretched tightly and stapled to the frame.
3. Cover the edges of the Silk and the staples with strips of gummed paper tape Painting the tape and the inside edges of the silk with shellac will make the screen last longer.
4. Make a base, slightly larger than the screen, from plywood and attach a wooden block at one end. This block should be the same height as the strips used to make the frame.
5. Fasten the frame to the base with pin hinges. This allows easy removal of the frame for cleaning, to change the cloth when it is damaged, or to use several different screens.
A squeegee can be purchased or made by bolting a piece of flat rubber 1/4 inch thick between two pieces of wood. The squeegee should be a little shorter than the inside width of the frame.
There are seven basic steps to making a one-color silk-screen poster:
1. On a sheet of waterproof paper such as the lining of a cement bag or heavy food wrapping paper make a pencil or ink drawing of the design to be silk-screened.
2. Cut the design out of the paper with a sharp knife or razor blade.
3. Attach the stencil to the underside of the screen wire tape. The centers of letters such as D and O can be attached to the screen with a small loop of tape. If there are any open areas of the screen showing at the edges, these can be covered with tape to block the paint.
4. Place a piece of paper or cardboard in position on the base and lower the screen.
5. Pour a small amount of thick water-base or oil-base paint at one end of the screen and spread the paint across the screen with the squeegee.
6. Raise the screen and remove the printed poster. By repeating the procedure additional copies can be quickly made. A paper stencil will make as many as 50 copies depending on the paper used for the stencil.
7. When the required number of copies has been run, remove and discard the stencil. Excess paint can be wiped off and the screen washed ready for use with another stencil. A solvent such as turpentine is used for washing oil-base paint off of a screen. Proper cleaning is essential if a screen is to be reused.
Stencils can also be made by the wax and glue method.
1. Make a pencil sketch of the poster to be printed. Trace this design on the silk with a soft pencil.
2. Paint the design on the silk with melted paraffin. A liquid wax called tusche is ideal for this purpose and is available from many art supply stores.
3. Paint a second coat of wax to assure a solid image.
4. Pour liquid glue at one end of the screen and spread it across the entire screen with a piece of cardboard.
5. When the screen is dry, turn it over and wash the wax or tusche out with turpentine or other wax solvent. The screen is then ready to print.
Since the liquid glue is not waterproof, such stencils should be printed with oil-base paints. Shellac can be substituted for glue for printing with water-base paints.
There are many other methods of making stencils for silk-screen printing. For high quality and large quantity runs, stencil films that are soluble in water or lacquer thinner are generally used. These are available in many places. Check with a local printer to see what he is using.
Silk-screen paint may be purchased commercially or Can be home made. Oil-base paint can be made by taking ordinary paint that has an oil base and thickening it with wood-filler, talc or powdered clay. Water-base paint can be made by mixing equal parts of cornstarch and soapflakes and coloring with tempera paint, food coloring or ink. Dissolve a half-cup of cornstarch in a little cold water, add 1 1/2 to 2 cups of boiling water, boil and stir until thickened, cool and add a half-cup of soapflakes; then add coloring.
If the ink is too thin, it will run under the stencil; if too thick, it will clog the screen. The consistency should be halfway between that of heavy cream and pudding.
When using the silk-screen process, it is important to learn the compatibilities and incompatibilities of stencils, paints and solvents. The paint must not dissolve the stencil because the image will be destroyed. The stencil must have a solvent or the screen will be ruined. Two types of pain are generally used, water-base and oil-base. The chart shows combinations of stencil, paint, and solvent. There are exceptions to this general guide, but the instructions on paint can usually give detailed information.
Water-base paint Use indoors Solvent-water
Good for a limited
Solvent to adhere stencil and to remove stencil
Hot water to remove glue
Relief printing, ordinarily associated with printing presses and typesetting, is a useful process for small-scale duplication. In this case what is needed is some means of raising the surface to be printed above the surrounding surfaces. The raised image is then inked by rolling an ink-covered roller over it. Following that, the inked surface is pressed against the copy paper, or the copy paper is placed on top of the inked surface and brushed with a stiff brush or rubbed with the back of a spoon.
The printing surface may be made in many ways. With the traditional linoleum block or woodcut method, the background of the illustration is cut away to leave the raised original surface of the block as the printing surface. Similar results can be created by cutting the areas to be printed from cardboard or an inner tube and gluing them in place on a block of wood. The surfaces of the shapes may then be inked and printed the same as a woodcut. The roller used for inking the printing surface should have a rubber surface. A roller may be purchased for the job or may be made by fitting a wire handle to a wooden dowel covered with a piece of an inner tube.
The ink should be thick. Printing ink, mimeograph ink, or silk-screen ink will do. Roll the ink on a smooth surface, such as glass, to distribute the ink evenly on the roller. Then ink the printing surface with the roller.
One method of relief printing, called a potato print, uses fresh vegetables as the printing medium. This is a good way to make small, repetitive patterns on paper, cloth or board. Depending on the size of the desired image, cut a potato, carrot, or similar item in half, and carve the negative or background image in the flat surface. With vegetables, water-base inks work better, but for small symbols try using a stamp pad. Work rapidly in hot climates.
Thermal duplication, as the name implies, is a heat process In operation, a master copy in combination with a specially treated copy paper, passes an infrared lamp in the copy machine. Areas on the master that block the passage of infrared radiation generate heat and transfer the heat to the accompanying copy paper to produce a black or brown image.
A master to be used with the thermal duplication process must have an image that will absorb infrared radiation. Ink containing carbon particles (India ink and some writing inks), graphic pencils, and specially made ball point pens will work. Most marking pens (Magic Marker, etc.) and dye images will not work.
Thermal duplication paper will produce acceptably sharp copies of images the size of ordinary typing and larger, but will not resolve or reproduce very fine lines or accurately reproduce intermediate shapes of gray. Copies can be damaged by long exposure to sunlight or intense heat.
The thermal duplicator can produce transparencies on several types of transparent film. The film designations vary from one manufacturer to another; but, in general, they are available as black line on clear background, black line on color background, and colored line on a clear background. In addition to paper copies, the thermal duplicator can be used to produce spirit masters on special master sheets that can then be run on the spirit duplicator, which reduces the cost of multiple copies. Several manufacturers have also developed stencil duplication masters that may be cut on the thermal duplicator.
The only real limit to duplication processes is the imagination and resourcefulness of the individual. If one process won't fill the bill, try combining processes. The number of variations of duplication processes that have been developed is nearly inexhaustible. To find out if something will work, try it.