( Originally Published 1963 )
Purpose.—The negatives or other film material received from the camera room are untrimmed, on larger material than page size, and cannot be used by the imposer until opaqued, trimmed to proper size, and combined with illustration material as necessary. The finishing tasks receive all of this photographic material and arrange it into uniform complete page-size pieces ready for imposition.
Materials.—Various brushes, ruling pens, compasses, french curves, rulers, straightedges, T-squares, triangles, dividers, various lithographic needles and knives, magnifiers, pins for registering two or more pieces of film or paper, abrasive hones, opaque and clear pressure-sensitive tape, paste opaque, scissors, cleaning solvents, sharpening stones, and ruled page guides are used.
Equipment.—Light tables (to provide light below film on a table surface), punching devices to punch films in register, etching table to provide chemical spot etching of image materials, lineup tables to pro-vide accurate layouts for stripping, airbrushes for staining and special opaquing, cabinet or fan-type film driers for quick-drying film, trimmers of various sizes to trim and cut apart film materials or paper are required for general use.
Opaquing.—Films delivered from the camera room contain many defects such as scratches and pin holes caused by dust or foreign matter in the light path of the image. These must be painted over with a brush and a pigmented paste which is usually made in a water base. Very close or critical opaquing should be done under magnification. If a square image is to be reproduced, as in a picture with a background, opaque is used in a ruling pen to draw true straight and square lines to outline the material desired, and the other unwanted work is opaqued with a brush or airbrush. Another method is to use translucent pressure-sensitive tape to outline the halftone area. This tape will not permit exposure of the plate coating even though it is possible to see through it. If the line is a curved line, a compass or curve is used. Separation of images into two or more colors from the same piece of copy is also accomplished by various means of applying opaque.
Silhouetting.—When the background or any other unwanted part of an irregular image is to be eliminated, a procedure called silhouetting is used. This consists of applying opaque up to the very edge of the image to be printed and extending through the unwanted portion. This results in a framework of opaque approximately 1/2 inch wide surrounding the entire image to be printed. This procedure is used primarily but not exclusively when removing background or other unwanted portions of halftone negatives or positives.
Vignetting—When a portion of a negative, primarily a halftone negative, is desired to be softened, diffused, or gradually eliminated, a procedure known as vignetting is employed. The most widely used method of vignetting a negative is by use of the airbrush, but dry brushing, crayon, graphite, and other special pencils are also used at times with satisfactory results. The airbrush is filled with dilute opaque and applied to the negative in such a manner as to barely diffuse the image at its nearest point and increasing in density away from the image until the desired results are obtained. This procedure differs from the previously discussed silhouetting in that the image edges are merely softened and the opaque is gradually intensified away from the desired image until the background is lost.
Ruling.—On many occasions when working on negatives or positives it becomes necessary to apply opaque in a perfectly straight, uniform line, called ruling. To accomplish this, one of several types of pens, including ruling pens, is used. This procedure is found necessary and convenient in many instances such as squaring halftones, smoothing a ragged line, ruling straight lines, connecting broken lines on positives, bordering, tooling out borders between halftones on positives and negatives, where tolerances do not conveniently permit brushwork. It is also convenient for silhouetting straight-line images on halftones. A ruling-pen attachment used on a bow compass can be used to accomplish the same results in the drawing of an arc or circle, which in many instances is required and necessary.
Creating images on positive film.—Very frequently because of either critical register, color tints, inability to produce part of original art or copy, or for other reasons, it becomes necessary to create an image or images on positive film that are not otherwise obtainable. There are several ways by which this can be done. One method used is to reverse a negative to a positive by opaquing and masking to create certain other areas that will print differently than the original negative. Another method is to use clear film to overlay that part of an image to be created by using opaque or pressure-sensitive sheeting and the appropriate tool or tools, create by handwork the desired image or part thereof. This type of work is done in the reverse since it must be remembered that we are working on positive, not negative, film but this is very readily overcome by simply reversing the completed positive back to a negative.
Color separation.—It is often necessary to print more than one color and to produce these separate colors from the same piece of art. Color separation is required. When, for example, it is desired to print a portion or segment of an illustration in one color and the remainder in another color, whether overprinting, abutting, or separated completely from all parts of the image, a negative that is completely masked out with the exception of that portion or portions wanted to print in a color that differs from that of its counterpart is produced. In this type of work it is essential that register marks be used to provide exact individual colors printing in correct position.
Chemical etching.—On a few occasions, because of unevenness of copy value, exposure, or development, some very thin lines of an image or parts of an image may partially develop across the image area. Several reducing solutions may be used to selectively eliminate this unwanted image and produce a clear image. This material also may be used to change the dot size of an area of a halftone and thus change the gray value of a portion of or all of a picture. It is difficult to limit the action of these reducers and care must be taken not to change areas of an image which are correct and no change is desired. Reducers may also be used in certain instances where large areas of an image are to be removed and it is undesirable to use a knife or scraper.
To change tonal value or color balance.—A desired change of the tonal value or color balance and densities can be achieved by the con-trolled use of certain chemicals that will etch a negative or positive or a portion of either so the results obtained will produce a stronger or lesser color or more or less density (whichever case applies) on the printed sheet.
Remove unwanted emulsion (without hand tools).—On a number of occasions it becomes necessary and even imperative to clear or clean away emulsion on a negative or positive without marring or scratching the film. Hand tools normally used to engrave cannot be used. The use of etching chemicals, especially if the emulsion is to be etched up to and abutting an image that is wanted to print, can remove this unwanted emulsion.
Chemicals and materials used.—There are a number of chemicals which can be used for etching and other purposes at the negative finisher's disposal. After a careful inspection of the negative or positive, a trained eye and experience will determine which particular chemical or combination of chemicals are most suitable for securing desired results. A list of the chemicals which are used in the Government Printing Office is as follows: copper chloride, ferric sulphate, hypo, ferricyanide, 20% sulfuric acid (used as a stop solution), clorox (bleach), ethanol, and alcohol.
Cutting.—By means of steel needles with various shaped points, each designed for a specific use, the finisher removes developed portions of a silver image for any of the following conditions: (I) to scribe rules in tabular column matter; (2) to scribe borders or underscoring; (3) to insert accent marks in text type matter which cannot be conveniently inserted on the copy; (4) to correct filled-in hairlines in lettering; (5) to correct weak lettering caused by variation in copy, incorrect processing in photography; (6) to alter or add to existing lettering on an already completed negative rather than correct original copy; (7) to correct damage caused by handling in any part of the process; (8) to correct faulty register or to establish register marks, to insure proper printing of one color with another; (9) to a limited degree, correct faulty images on a press plate.
Stripping.—For a variety of reasons it is necessary to insert one piece of film into another. Some of these reasons are (I) to insert corrected lines; (2) to place halftone illustrations into line text; (3) to insert negatives of different focus into each other; (4) to combine elements which are on separate pieces of copy; (5) to revise negatives previously made and stored; (6) to insert folio lines into negatives of text pages made prior to the knowledge of page sequence; and (7) to delete matter from an existing negative which cannot be done by opaquing.
Procedure in stripping negatives.—The piece to be inserted is placed in correct position on the base negative. Small but visible corresponding guide marks are scribed on both the insert and the negative into which it is to be inserted. In making these guide marks, care must be taken so that they do not touch or run into any part of the image that will ultimately be printed. An area on the base negative slightly larger than the image of the insert (usually 1/8 inch on each side) is scored. In creating this opening, the previously scribed alinement lines are cut so that they appear at two edges of the opening. The scored portion of the negative is creased and the unwanted film taken out of the base. By placing the cutout area over the insert and simultaneously matching the corresponding guide marks previously provided, the insert is scored by following the size and shape of the opening in the base negative. All that remains is to break off the excess film at the scored lines and tape the two together. It is essential to insure that no light pass between the joined pieces of film. This is accomplished by covering the scored lines with a tape of a color, usually red, which will not affect the plate coating. Any tape which might be covering any part of the image to be printed is cut away with a sharp blade.
Using a grid to square stripped halftones.—Stripping, which involves a halftone that needs to be squared, can be accomplished by the use of a grid, which is a film positive ruled off in picas and half picas in both directions at right angles. The procedure for stripping the halftone is identical to that given in the preceding paragraph but particular care in placing of the guide marks is required. After careful positioning, a piece of cellophane tape is placed across the pieces to hold them in position temporarily. The next step is to place the stripped, tacked negative and halftone over the grid. The grid lines will show through the halftone and by using care to place the guide marks in line with those of the grid, the stripping tape is placed over the scored edges and the halftone to the size on the grid which is the final correct size of printing image. In this manner, the tape serves the purpose of eliminating the scored lines and also outlines the image. This procedure can also be accomplished by the use of clear tape, ruling pen, and opaque in place of the stripping tape.
Register marks, bleed and trim marks.—In all multicolor printing and very frequently in single color work, if two negatives are made for surprinting, register marks are required. In order to assure that these various colors or tints and line negatives fit or register, the stripper is called upon to place these register marks on the negatives as exactly perfect over each other as possible. Register marks are two very fine and uniform lines scribed at right angles to each other in a convenient location. They may come with a variety of different designs. Other marks that the stripper is sometimes required to insert are trim marks, bleed marks, and fold marks.
Care in stripping, what to avoid. Buckle.—A buckle is caused if the insert is not cut slightly smaller than the corresponding opening into which it is to be placed. If there is any binding of the insert, the film will buckle when tape is applied since it cannot flatten out with the tape holding it in place. This condition will cause loss of contact, distortion, and even complete loss of image detail in platemaking or at the contact printer when composites are to be made.
Overlapping.—In an overlapping strip, the cause is the same as that stated for buckling, but instead of the insert being forced into an opening too small for it, it is overlapped on top of the base film and taped, resulting in a double thickness at the edges at fault. When this negative is put into the vacuum frame, complete contact cannot be made due to the double thickness at its overlapping edge. Again the results are very similar, distortion or partial to complete loss of image at its over-lapped edges. Since both of these conditions are brought about by the same reason, incorrect fitting of pieces, accuracy in scoring an insert for stripping cannot be overemphasized. Further, if it is noted before stripping that the insert is too large to fit conveniently into an opening provided, it is much simpler to immediately recut the insert to fit than to repair it after stripping is done.
Crimping.—Photographic film, unlike paper or cloth, is for the most part made of an acetate base. This basic film is normally limber enough to stand rolling and semifolding but it cannot be completely folded or crimped without damaging effects. When this acetate base film is once creased or folded, the resulting damage is a crimp that cannot be completely flattened. If this crimping occurs in an area that is to be printed, and especially in a tint area, the negative will be useless, requiring a new one to be made. If in the case of a multicolor job one negative is to be made over, it frequently becomes necessary to remake the complete set of negatives that corresponds to that particular negative in order to maintain proper fit and register. If the crimping occurs in a portion or section of the negative that is not to be printed and provided it is not too close to a critical area such as large tone, where it could cause a contact problem, it is usually not troublesome and can be disregarded. Otherwise, and provided it is in a nonprinting area, other steps can be taken to eliminate the con-tact problem, such as cutting out the crimped area and replacing it with a solid piece of film.
Scratching.—When working with photographic negatives, one word stands out above all others—that word is "Care"—care in handling, care in all phases of work to be done, care in determining what is to be done and how best to do it. Any mark on the emulsion of a piece of film will admit light and expose a plate the same as image areas are ex-posed. Even a fingernail, if rubbed hard or roughly across a negative emulsion, may cause a damaging scratch. Any unwanted marks or scratches must be opaqued or masked and in many cases small scratches or holes will be overlooked and become part of the image. Scratches may also be caused by rubbing negatives across sharp table edges, tape dispensers, tools, and other rough surfaces. It should also be noted that a wet or damp emulsion is more subject to damage than a dry one and can under unusual circumstances be rubbed off by hand. Alinement marks made on a negative to be inserted represent the overall exact size of the image but it is imperative that these marks do not extend into the halftone image. On line negatives such a mark could be opaqued to the image into which it might accidentally have been cut or scribed, but in a halftone negative this is not possible if the mark runs into that part to be printed. The exception to this rule would be where the image is to be covered by tape or opaqued when squared. In any event the ideal way to place the alinement marks on any insert is to endeavor to keep them a fraction outside of the furthermost points to be printed, so that they will be either masked or taped off. The corresponding marks are not critical in length and if they extend beyond that portion to be cut away they are sufficient, although they should be kept at a minimum for neatness and good workmanship.
Excessive taping.—An excessive amount of tape used in stripping causes a condition closely related to overlapping. Overlapping was noted to be two thicknesses of film which caused poor contact on the vacuum frame. Several layers of tape can cause the same result. Although it is true that the tape is on the base side of the film and not the emulsion side, the difference in thickness due to excessive taping creates tension between elements of the flat and the vacuum is there-fore not uniform and can cause a wavy or puckered effect which results in distortion and spread of the image.
300-line screen.—The finest screen used in the Government Printing Office is 300 lines per inch. This screen is so fine that to either tape it square, strip it, or even opaque it on its emulsion side would interfere with the extremely close contact that is desirable in reproducing the fine dots of the image. These screens are never stripped or taped. It is instead ruled square by the use of a ruling or lithographic pen and opaque on its base side only in order to prevent any loss of contact between the film emulsion and press plate or another piece of film. The emulsion side is always left without any markings or cuts.
The preceding paragraphs are descriptive in their use and application and are also intended to point out some of the undesirable effects to be guarded against and the things to recognize and avoid. A careful stripper will use good judgment in determining the course of action he will take before making any cuts that could be irreparable and time-consuming. As he gains knowledge and skill with time, improved capability enables him to know almost at a glance what errors and pitfalls to avoid before the damage is done and the negatives or work are spoiled.
Preparation of negatives and/or positives for compositing.—Preparation consists of being certain that register marks are correct, opaquing or silhouetting is complete, that necessary reverse negatives have been made, all necessary handwork finished, that tint negatives are correct, and that all necessary stripping where called for has been completed. Where multiple composites are made on the same sheet of masking it is also necessary to check the layout of the various negatives to be sure that they will fit conveniently on both sheets in order to register them. The individual negatives or positives should also be checked to ascertain if they will register before starting steps of compositing.
Compositing.—There are several methods used for compositing several images into a single film. These may be a simple composite sandwich, a punch and pin group of images, or a complicated autopositive layout. Regardless of the method used, the craftsman must use the most practical and correct method for a particular requirement.
Registering negatives.—Before any compositing of any type can be accomplished or even started, it must first be determined just exactly how the negatives will register. In most cases the negatives will carry register marks which were prepared along with original copy or they may have only guide lines of some sort to establish register. Occasionally original register marks cannot be used for critical work be-cause of the tendency of photographic film to expand and contract and these negatives have to be reregistered. Register marks which were not properly registered or omitted in the preparation of original copy require correction of registration.
Punching register holes in negatives or masking paper.—With the register of the negatives established, some means to hold this register constant during exposure for compositing is essential. A register punch, a device that punches two or more holes in identical positions either in film or paper, is used. In conjunction with this punch, register pins of identical size are used.
The use of the register punch in the negatives themselves requires that register be established between the two or more films first and these are held together in a fixed position and then register punched. The procedure is reversed when the holes are punched in masking paper. The required number of sheets of masking paper is first register-punched to accommodate the necessary number of exposures. The negative for the first exposure or group of negatives is attached to one sheet, base side down, with care taken not to overlap negatives. After these negatives have been firmly taped down, the entire sheet is turned over on the light table and the masking is cut away to expose only those portions to be printed along with any register or guide marks needed. By using register pins, the second and succeeding sheets are placed over the first, base side up, one at a time, being careful to keep the identifying set of holes together. Openings are then cut out of the mask to expose the register marks only. After these openings have all been cut out of the succeeding masking sheets to insure exposure of correct register marks, the original sheet is turned over on the light table so that the negatives are emulsion side up. The second exposure sheet is placed over the first and register pins are pushed through the punched holes of both sheets to keep them exactly in position. The register marks of the negatives on the first sheet are now visible through the openings in the second sheet.
The second exposure negative or set of negatives is prepared by positioning register marks or guide lines of the individual negatives over those of the first sheet in exact position. This procedure is followed for all following sheets of masking paper and negatives. The individual sheets are then marked with sequence identification, a cam-era room order is issued, and all flats are sent to the contact frame to produce a composite positive. This positive will for all intent and purpose be identical to the finished printed sheet or page. If any further correcting is deemed necessary, the stripper has the opportunity to see the positive and make the necessary corrections before reversing the positive to a final negative ready for platemaking and printing.
Angling tones (or tints).—Halftones and tints are involved in a majority of all composite work. Very frequently it is necessary to print tints of the same or different percentages in such a manner that they join each other, overlap slightly, overprint each other completely, or in some cases overprint a halftone illustration. If any two pieces of film tints, whether identical percentages or otherwise, are placed over one another at random or moved about, a series of variable visual patterns will occur that will change with every angle of placement. This phenomenon is known as a moire pattern. This pattern is undesirable and must be eliminated before the final negatives are made. These objectionable patterns are eliminated by changing the angle of the tones until they disappear, or are so slight that they are no longer a visual problem.
In composite work, if two or more tints are used one over another, primarily as in process color printing, the ideal pattern that the crafts-man endeavors to reach by tones angles is a grouping of dots in such a manner as to form a rosette.
Rubylith.—When any film, whether positive or negative, is to be exposed on another piece of unexposed film or on a sensitized press plate, that portion of the film which allows light to penetrate through will print and the opaque portion will not. However, the opaque portion need not be light impervious, since there are several materials which by their colors render white light harmless to unexposed film or sensitized plates. Such a material is called Rubylith. This is a very thin red acetate sheet with a pressure adhesive on one side which can be used as a translucent frisket to permit masking of large or irregular areas of an image and can simply be cut away with a knife.
Mask-O-Lith.—This material, more commonly known and called "goldenrod," is the most extensively used masking material in compositing. Sheets are provided in convenient sizes of 20 by 24 inches and 24 by 30 inches. This Mask-O-Lith or goldenrod is a fairly heavy yellow or orange colored paper or plastic sheet that renders white light insensitive to film. Therefore, it is possible to expose only the image part of a negative.
Quicktone.—Everything on copy that is white appears as black on the negative and vice versa. Taking this into consideration, negatives are almost entirely completely black or opaque. Assuming that two or more negatives must be very closely registered, such as maps, posters, or charts, and unless the existing register marks are completely accurate, the registering of these negatives is difficult and in some cases impossible due to the fact that we cannot see through an opaque surface or substance. Register can be more easily accomplished through trans-lucent materials. There are two methods of accomplishing this. One method is to reverse the negatives to positives. This leaves only the image to be registered, and though this method is acceptable, it requires duplicate films and considerable expense.
A second method is by the use of a chemical process known as Quick-tone. This procedure consists of applying a chemical to the negative for the purpose of transforming the opaque image into a translucent one, which can then transmit visual light. Precise register can easily be achieved. After this has been accomplished, the translucent negative is simply redeveloped so that the original opaque emulsion is restored and it is ready for platemaking.
Autopositive.—This is a method by which a positive may be made directly from a positive or a negative made directly from a negative. It is also possible to subtract an exposure by the use of yellow light. This can save time and provide a convenient method of producing many effects in tones and reverses.
The differences in procedure using autopositive film are many and more careful preparation is required than for the conventional method. Since there is no intervening positive to correct, the negative returning from the autopositive frame is the final one and must be correct without further review. The masking paper used must be impervious to any light. The negatives being masked for compositing must be base up, which is the opposite of the conventional method. Instructions which accompany masks must also indicate any additive or subtractive exposures required.
Advantages.—There are many advantages when compositing by the autopositive method, but the chief advantages are accuracy in register and elimination of the intermediate step of making a positive prior to making the finished and final negative. Some of the other advantages are (1) accuracy in butting tint halftones together; (2) ability to more easily put reverse printing areas or text in a tone negative; (3) the complete uniformity of emulsion, density with lack of defects, which eliminates much time that would otherwise be spent in opaquing or repairing tints and halftones; and (4) simplification or elimination of some of the copy preparation which is necessary when done by conventional method.
Disadvantages.—Although compositing by the use of autopositive film has many advantages, there are disadvantages. The chief one is the lack of ability to see through the masking paper used. As was pointed out earlier, the normal masking sheets which are used for conventional composite work cannot be used here because autopositive film is sensitive to the light passing through the yellow or orange colored paper. It is also sensitive to the red masking tape normally used in stripping. It is, therefore, necessary to use either a completely black impervious masking paper and black tape or one so heavy in texture and color that any light is rendered insensitive to this film. The use of a heavy textured blue paper has proved to be satisfactory but very difficult to work with. To use these opaque masks, a yellow carbon-type paper is usually used to mark guidelines on the masking sheet to indicate the areas to be cut out. These guidelines are determined by placing the transfer paper between negative and mask and a line drawn around the image on the negative thus transferring a yellow mark on the opaque masking paper. All taping is done with black tape. Negatives used for autopositive work are placed with their emulsion to the mask and a deep cut through the mask sheet might also cut into and damage the emulsion. To overcome this possibility, a sheet of clear acetate is placed between the mask to be cut and the emulsion. This prevents cutting into the film. The acetate is removed when cutting of the mask is finished.