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#02-06, Singapore 339944
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Colour Printing
Products may be printed in two or more colors by almost all of the processes described earlier. The simplest method of color reproduction is flat-color printing. A separate plate is prepared for each color desired. Plates are then printed in sequence on a single sheet of paper. Each plate is covered with the desired color ink and then printed in register with all of other color images. The process-color printing method is used to reproduce full-color pictures such as the colored continuous tone photographs. Process-color activities include: color separation, color correction, and color reproduction.

Colour Separation
A beam of white light passed through a glass prism results in a rainbow of color. This is because white light is really a mixture of all the colors of light. Each color refracts or bends differently as it enters and leaves the prism.
Three colors of light-red, blue, and green-can be used to reproduce white light, Figure 7-30. Where all three colors of light overlap, white is produced. Red, blue, and green are called additive primary colors bcause added together they form white light.

Colour Printing
Where any two additive primary colors of light overlap, a third color is formed. Red and blue to form magenta. Blue and green form cyan. Red and green combineto produce yellow. Magenta, cyan, and yellow are called subtractive primary colors because they subtract colors from white light to form black.
Binding Printed Materials

Comb Binding

Plastic comb bindings are more vulnerable to damage than spiral bindings. They hold adjoining pages more tightly in register with each other than spiral bindings. They come in several colors and allow screen-printing on a document's spine. They can bid pieces up to 3 inches thick.

Comb bindings allow pages to lie flat when opened. However, they cannot be doubled back. Inserting them is a hand operation that is quite costly for large numbers of documents.

Spiral Binding

Spiral bindings may be made of either plastic or wire and allow the printed document to lie flat and to double over, useful characteristics for documents such as technical manuals, notebooks, and calendars.

Spiral binding allows play between pages. One cannot add pages to documents once they are spiral bound. Also, rough handling may crush the spirals. Spiral wire coils range from 1/4" to 2" in diameter. They can bind books of up to 24" in length.
 

Wire Binding

A Wire-O binding holds the covers and pages of a document firmly in place by a double-loop wire inserted through holes drilled in their left edges. All of the document's pages lay flat when opened, can turn easily through 360°, and stay in perfect registration with adjoining pages.

Wire-O bindings come in nine standard colors and loop diameters from 3/16" to 1-1/4". They can handle documents from 1/8" to 1" thick. Often, they are used to bind reference books, reports, proposals, and calendars. They are durable, but do not permit printing on the document spine or the insertion of new pages.
 

Saddle Stitching

In saddle stitching - the way most booklets, magazines, catalogs, and calendars are bound - wire staples hold the piece together. A machine drives then through its backbone fold to the centerfold, where they clench. A saddle-stitched printed piece lies almost flat when opened, a convenience for readers.

However, saddle stitching involves certain mechanical requirements. A saddle-stitched document must be at least eight pages long and increase in length in four-page increments. Saddle stitching is a good choice for binding documents of up to 64-80 pages on 60 lb. to 70 lb. paper. Documents involving more pages, or thicker than 3/8", demand some other type of binding.

Perfect Stitching

To produce a perfect-bound document, the piece's folded signatures are gathered together in page sequence, clamped together, and placed in a machine that slices about 1/8" off their left edges. Then roughers mill the newly sliced sheet edges to prepare them for gluing. Finally, the edges receive an adhesive application and adhere to a backing.

Perfect binding is well suited for use with books, thick magazines, annual reports, technical manuals, and catalogs. From a minimum thickness of 1/8", it works well with a wide range of document thicknesses and trim sizes. However, the paper used should not be heavier than 100 lb. Book stock, with the grain running parallel to the piece's spine.

Coil Binding

A continuous, spring-shaped piece of plastic, this durable crush-resistant bind allows a bound book to lay flat, even back on itself for easy reading.


Case Binding

In case binding, most often used in book production, a minimum of 60 printed sheets is folded into 16 or 32 page signatures, which are collated and sewn by machine. The sewn edges are coated with glue. Then a strip of gauze adheres to the document's spine. Finally, a book and its covers are placed in a casing-in machine, which pastes the endpapers and fits the cover.


Tape Binding

This process places a cloth strip of adhesive tape down the bind edge of the book and wraps around about half an inch onto the cover front and back.

Top 11 Notes for Film Checking
1. Check the completeness of required information
   A. Information of layout/word/color/dimension (drawing)
   B. Design/plate making (modifying)
   C. Film test table
   D. Carton box/ trademark card

2. Whether each film is clean

3. Whether the film has scratches

4. Whether there is a lack of Corner mark

5. Whether the page and word are correct

6. Corner marks and accuracy of overprint of the color plate

7. Whether the figure is complete

8. Correctness of the dimension

9. Whether it bleeds

10. Whether there is color separation error in each color plate

11. Whether the grip position and places around film have:
    a) Product name (and output lot number),
    b) Dimension,
    c) Colour batch,
    e) Output date,
     f) Producer code,
     g) Colour correction stripe.
Glazing and Calendering Technology in Printing
A. What is glazing?

Glazing is to smear (or spread and print) a layer of transparent paint (glazing oil) on the surface of printed maters. After being leveled, dried and calendered, the surface of printed maters would form a thin, well-distributed and transparent glossy layer. Glazing includes full-glazing, part-glazing, luster glazing, matte (delustering) glazing and special paint glazing etc.

B. Why glazing?

Glazing can beautify and protect printed maters, and can enhance the effect and functional value of printed maters. After being glazed, printed maters would form a smoother surface which enables even refraction of incident light and brighter ink layer. It is a coating finishing with glazing oil, and a protective treatment for the surface of paper or paper printed maters before final procession. The surface of printed maters would be covered with a layer of glossy film after being glazed. Glazing can be applied in:

- Book decoration, such as book jacket, cover, interleaf, calendar, monthly calendar, poster, propaganda sample etc. Printed maters would have better luster and brighter color effect after being glazed.

- Package-décor paper maters: such as paper bags, envelopes, trademarks etc, able to beautify and protect products.

- Daily necessities and food: such as trademarks of cigarettes, food and lotion, able to achieve damp-and-mildew proof effects.

- Copper foil on hard cover, able to beautify the product with gold-like high brightness. Glazing can also produce better tack force between copper and base.

C. Technical requirement for glazing oil

Perfect glazing oil shall be colorless, tasteless, glossy, fast-dried, chemical-proof and the following:

- film shall be highly transparent and color-fast. Whether there is a layer of transparent film is crucial to good glazing effect of decorative printed maters, meanwhile, figures and text shall not change colors after being dried, nor change color and yellow after being exposed to sunshine or used for a long time.

- The film shall be wearing-resistant to some extent. Some glazed printed maters are required to be resistant to wearing and scraping, for surface of printed maters is bound to suffer from friction through the production line including high-speed box machine, carton box packing machine and book jacketing machine etc.

- Certain flexibility and elasticity shall be ensured. Glossy film formed on the surface of printed maters by glossy oil shall have good elasticity so as to suit the flexibility of paper or board, and prevent damage, cracking and shedding.

- Environmental-resistance of film shall be good. Some glazed printed maters are used to produce various kinds of packages. In order to ensure good protective function to the packed products, the glazing film shall have sound environment resistance. E.g. packages of food, cigarette, cosmetics, clothes etc shall be damp-and-mildew proof. Besides, dried film shall have stable chemical performances, and can not change its property by contacting weak acid and base substances in the environment.

- Ensure certain adhesiveness to the surface of printed maters. Influenced by ink layer density of figures and text, surface adherability would be greatly spolied. Therefore, in order to prevent the dried film from cracking and falling off, film shall have strong adhesiveness.

- Ensure good leveling and smooth film surface. Printed stock materials are various, plus influence of printing figures and text, the surface absorbency, smoothness and moisture differ a lot. In order to enable glazing paint to form a sooth film on different product surface, glazing leveling shall be conforming and the shaped film surface shall be smooth.

- Ensure wider application scope of post-press finishing. Printed maters usually need to undergo post-press procession after being glazed, such as embossment processing, hot foil stamping etc. Therefore, post-press application scope of glazing film shall be wide. For example: heat-resistance shall be good. Tacking shall be avoided after hot foil stamping; solvent resistance shall be high. Blistering, crinkling and sticking phenomena shall be avoided when the film is dried.

D. How to choose glazing oil?

Glazing oil should be selected in the principle of being scientific, economic and functional. Scientific means to study whether glazing oil can suit each physicochemical performance during glazing and using of printed maters. For example: cover and jacket of books, magazines and albums of painting require glazing oil with high-transparency, sound scraping & folding resistance; food packages requires nontoxic glazing oil with damp & mildew proof function; packing boxes require glazing oil with highly stable chemical functions without color-change and yellowing under sunshine or lamp light, nor tacking phenomenon due to stacking. Economic refers to matching glazing oil with printed maters to avoid using high-class glazing oil to process medium or low-class printed maters. For example: up-grade printed maters could apply high-cost and quality calendering, UV curing glazing oil or solvent-based glazing oil with acrylic resin as the main solvent. In contrast, mass-produced textbooks can select medium cost ordinary solvent-based glazing oil with proper quality that can satisfy procession requirement. Functional means matching glazing oil with glazing equipment. For example, solvent-based glazing oil only suits normal glazing machine, while UV-curing glazing oil must be applied in machines with UV drying devices. For ethanol soluble or water soluble glazing oil, glazing machine shall be able to meet their drying requirement (the drying passage is generally required to be longer than 6m and temperature is required to be above 65℃. Moreover, labor and material saving and mechanical mass-producing demand shall also be considered in order to cut production cost and maximize output. Glazing oil shall be odorless, nontoxic and tasteless in order to meet the requirement for ensuring safety, sanitation and environment harmless. Selection scope could be wider in production site with good conditions and sound equipment ventilation. In contrast, glazing oil with balmy substances as the solvent must not be used, otherwise, operators’ health and environment would be harmed.

E. Requirement on the quality of glazing oil coated layer

In order to get satisfactory glazing effect, coated layer of glazing oil shall meet the following requirements in coating procession: even distributed coated layer, no sand hole, no blister and no un-glazed part. proper amount of coating. Coated layer can shape into film after being dried under certain temperature and coating speed. Coated layer is not affected by ink performance, text & figures area, and integrated density. Good leveling and certain adhesiveness with printed mater surface shall be ensured. Coated layer can be pasted onto the calendered surface in calendering belt, and is able to be peeled off without difficulty.

F. Elements influencing glazing quality

Elements that influences glazing quality are mainly: paper performance, temperature, ink and printed matter crystallization etc.

- Influence of paper performance. Glazing quality is affected by paper smoothness. Very sooth paper would have obvious glazing effect, while low smoothness paper or board would not obtain satisfactory glazing result, because glazing oil is almost absorbed by tough surface of paper or board. In order to solve this problem, you could apply casein foundation before glazing, or do glazing twice.

- Influence of temperature: Temperature between 18℃~20℃ would render perfect effect. Glazing oil is easy to solidify in winter, thus lead to uneven glossy film of the surface of glazed product. In order to solve this problem, glazing oil shall be preserved in heat-insulation places. If temperature of glazed oil is too low, i.e. lower than 10℃, you must add some solvent to dilute the original solution of glazing oil if it is un-usable after being kept for a day under 20℃.

- Influence of printing oil: Printing oil used for product to be glazed shall be solvent-resistant and heat-proof, otherwise, the text and figures of printed maters would turn grey or crinkle. The solution is to pay attention to the following points in selection of ink: A . Select ink being resistant to ethanol, ethanol solvent, acid and alkali. B. select color-fast ink with excellent luster. C. select ink with good adhesiveness to paper.

- Influence of crystallization. Print crystallization is mainly caused by overtime store of printed maters, too big area of base ink, too much dryer etc. Ink film crystallization on the surface of paper often cause printing failure of glazed oil or faults like “mottled face” and “pock-marked face”.

In order to solve the problem, we usually add 5% milk acid into glazing oil and mix them. The mixed glazing oil could damage the crystallized film on surface of printed matters, and enable the glazing oil to be evenly coated onto the printed matters and form glossy film.

G. What is calendaring?

Calendering is operated in coated glazing unit and hot press unit. Printed matters are coated with glazing oil in ordinary glazing machine, and hot pressed by stainless steel belt of the calendering machine after being dried. Then the surface of printed matters would form mirror reflection effect and gain high luster after being cooled and stripped.

H. Elements influencing calendering effect

Elements influencing calendering effect include: Calendering temperature, pressure and machine speed. Temperature: Appropriate calendering temperature can increase the thermal motion of paint film molecule and accelerate diffusion speed, which is favorable for the main solvent molecule in paint to re-moistening, gluing and permeating to surface of printed matters. Moreover, proper temperature could raise the plasticity of paint film, and greatly enhance the smoothness of surface under the performance of pressure. Appropriate calendering temperature can enhance the quality of calendering film layer, while too high or low temperature is unfavorable to calendering. When temperature is too high, viscosity of paint layer would be decreased, and moisture content of paper would plunge, which are not good for glazing and stripping. When temperature is too low, paint layer can not be fully plasticized, nor be well pasted onto calendering plate and surface of printed matters. Calendering effect would be poor, and it’s not easy to form film layer with high smoothness. Pressure: Pressure functions to condense and cut the thickness of paint layer and make it to form smooth surface layer. Over-pressure would damage the ductibility, plasticity and flexibility of printed matters. Difficulty of stripping would not happen easily. Speed: Pressure speed refers to solidification period of glazing oil in calendering. If the solidification period is short (high speed), glazing oil molecule can not perform fully with ink layer on the surface of printed matters. Smoothness of the dried film layer is poor, and so does the viscosity between glazing oil layer and ink layer.

Makeup Process of Books
- Impression

One impression equals 1/2 broadside sheet, for one folio (in the standard of folio printer), impression=page number/binding size (1) Impression=96/16=6, i.e. 6 impression means to use 6 folios (3 broadside sheets) to complete a book.

(1) One impression of the printing plate has 16 folios, 8 page numbers on the front and 8 on the back, which constitute an impression.

(2) A 16-mo book with 88 page numbers, impression=88/16=55. In theory, five and half impression, i.e. five and half folios could complete the book.

(3) A 16-mo book with 92 page numbers, impression=92/16=575, in theory, five and three fourths pages could complete the book.

(4) A 16-mo book with 94 page numbers, impression=94/16=5875, in theory, five and seven eighths pages could complete the book.

General Knowledge of Binding

Signature:fold the impression (cut or uncut) into several folds according to page number and sequence. The fold with multi-pages is called a signature of book-block. After collocating the folded signatures into volumes by order and combine them, it is called saddle stitching.

Impression >folding >collating >wrappering >saddle stitching >cutting

Method for glue binding:

impression→folding→collating→glue binding→wrappering→cutting

- Method for folding page number: fold the sheet from right to left—turn 90 degrees clock wisely till obtaining satisfied size. Turn the sheet from left to right horizontally, and cut a corner in the right bottom, then mark page number.



Saddle stitching and glue binding are introduced below:

The introduced knowledge of binding can serve as the foundation for correct make-up. Different folding and collating methods require different make-up methods, e.g. saddle stitching and adhesive binding makes up 16-mo book with 32 folios.

Saddle Stitching

Glue Binding


If you have understood the method for folding page number and collating method for saddle stitching and glue binding, you can make up the plate above.

Additional Methods used to Estimate Printing

The following eight procedures are used to estimate printing in addition to or in place of the described cost-estimating procedure. The most significant difference between these techniques and cost estimating is that each is based on the selling price of the job. We define selling price as the total dollar amount the customer will pay when the job is completed. It is represented by the sum of all manufacturing, material, and overhead costs, plus profit.

Price lists

Estimating from price lists is very common when the product line of the printing company is standardized. For example, many fast print businesses, offering standard sizes of prices for the array of products they offer. Because the work is standardized, it is much faster to utilize price lists than to cost estimate each job individually. Customers also may use the price list to determine the price of the work they are contemplating prior to contact with the business.

Large printing companies that offer standardized products, such as labels or business forms, normally develop a price list book that covers literally all products they produce. Each sales representative, who has been trained in its use, carries this book. When a customer desires a price for a certain quantity and type of label, for example, the sales representative is able to determine a firm price within a short time. Price lists are an extremely valuable estimating aid when they are accurately developed and updated and used only for the product lines for they were designed. In this age of increased specialization and standardization the printing industry, more and more estimating from price lists is being done.

Pricing on the Basis of Past Work

A common technique for estimating in the printing industry, especially for a mix of products produced in the same plant, is pricing on the basis of past work. Essentially, the estimator and sales representative establish and maintain a file of past jobs that have been profitably produced and for which production is geared. The salesperson uses this sample portfolio during the sales contact with the customer. Frequently, the client will select a product from the sample, with a request for a color change or perhaps a slightly different page size. Back at the plant, the estimator will pull the original estimate for this job, review it, and make necessary changes to reflect the modifications desired by the customer. The sales representatives will then return to the customer with a proposal stating exact prices for various quantity levels. If changes are limited, the procedure is fast and reasonably accurate. The technique leads toward product specialization that may be most profitable for the company in the long term.

In some cases, the procedure is modified somewhat: The estimator maintains a card file system of past job quotations. The sales representative then sells work without a sample portfolio and brings the work in to be estimated. At this point, the estimator refers to the card file for a similar job done perhaps three months ago and quotes that former price or one close to it. The filling system used must be indexed and cross-referenced to be a timesaver for the estimator.

Pricing by Standard Catalog

The most popular standard pricing catalog in the printing industry is the Franklin Catalog (Porte Publishing Company, Salt Lake City, UT). Using Franklin, almost any ellars.

There are three volumes of the catalog segregated by printing process: a letterpress edition (approximate size 6*9 inches), an offset catalog (approximate size 8 1/2 * 11 inches), and a letter shop and bindery catalog (approximate size 6 * 8 inches). Any of these may be rented from Porte Publishing Company for an annual fee about $55, which includes updated sections offered approximately four times yearly. The sections, which are categorized by type of work or type of paper used, are held in three-ring binder notebooks. There are also sections containing instructions for using Franklin, hour rates and various operational times.

Pricing by Competition

Using the prices charged by competing printers, as a basis for estimating is fairly common in the printing industry. Such information is available from many sources-from published price lists, from customers who are checking around for the best price on their job, from supply salespeople, from former employees of that business, or perhaps from table talk at a local association meeting. Once the information is obtained, it may be used to adjust or establish a price for a job under consideration.

Two major problems exist when pricing by competition. First, it is exceptionally difficult to verify if the obtained prices are accurate for the described product and quantity. How can the accuracy be checked? Second, there may be little, if any, resemblance between the companies comparing prices. Each company may have entirely different types of equipment, different production techniques, and different types of personnel with varying levels of experience. There may also the tremendously different accounting, costing, and estimating procedures. if the competitors have very little in common, then costs and prices will tend to fluctuate significantly.

The advantage of pricing by competition is that it is a simple procedure once the information concerning the competitor's prices have been obtained. It is possible to undercut the competition's price and subsequently increase the volume of work by winning those jobs that normally would go elsewhere. Of course, while production may be up, costs to cover such production may not be recovered because they were cut to beat the competition. The net effect, should this happen, is bare bones survival or future dissolution of the company through bankruptcy. Consider this situation: If each printing plant in the community priced work by comparison with the competition, a price-cutting cycle could easily begin. Those plants that refused to cut prices would lose business to the firms that were offering the best deal. Those plants that cut prices would be doing a tremendous volume of work, perhaps much of it at cost or below. The net effect of price-cutting is a vicious cycle that can hurt the entire printing community.

It is safe to state that most estimators and sales representatives, at least once in a while, attempt to meet or beat the competition's price on a job they consider important. In fact, it is reasonable to assume that some printing plants price their work as much as possible on competitors' bids and may even make money if the competitors know their costs and pricing structure well. Consistently making a profit when pricing by competition, however, is more a product of luck than of skill.

Pricing by the Chargeback System

Some commercial printing plants, and many in-plant operations, use the chargeback system to price the value of their printing. The chargeback procedure uses actual production and material cost data accumulated as the job is completed, as opposed to estimating what is expected to occur before the job ever begins production. Actual time and material costs are tracked during production and summed at the completion of the job. In the commercial printing segment, a reasonable profit is added to the actual costs to arrive at a final selling price for the customer. In-plant shops, doing captive printing for a parent company, may or may not add extra dollars for profit.

An advantage of chargeback is that the customer pays only for the actual time worked and materials consumed for a job, eliminating any differences between the estimate cost and actual cost of the job. Essentially, chargeback procedures eliminate or reduce the estimator's involvement in such jobs since prices are based on actual and not estimated. The estimator's time can be spent on other jobs, which is another advantage.

The one disadvantage of chargeback is that since no estimate is prepared, no proposal or quotation is offered. Thus, customers may be surprised at the final price of a job and consider it to be excessive. Without a proposal or quotation stating specific dollar amounts, the question of whether a contractual agreement exists between the printer and the customer is possible.

Pricing by the Ratio of Paper Cost to Selling Price

This estimating technique is simple and uncomplicated. The procedure essentially involves a ratio of paper cost, which is the major material used in most printed products, to the selling price of the job. Initially, the cost of paper for an order is determined. The estimator then multiplies this cost by a specific ratio figure-for example, four-thus calculating the selling price for the printed job as a function of paper cost.

This technique does not reflect the actual costs incurred during manufacture of the product, but is accepted because it is extremely easy to execute and, in the view of some plant owners, it is as accurate as any other estimating system. The key, of course, is defining the exact ratio figure that best provides for full job-cost recovery and profit. Opinion varies as to what the paper cost ratio should be numerically and how it is effectively determined.

Pricing by Guesswork

Some printing managers believe that definitive that cost estimating is a waste of time. They base this reasoning on the fact estimating requires standard times and budgeted costs, both of which are actually averages; that many mistakes occur during the estimating process; and that too many changes occur during production that simply cannot be determined during estimating. So instead of estimating at all, these managers use intuition to determine a reasonable price for each job. In some cases, they may review the production requirements that are needed to do the job and include that in their guess. In other cases, they may quote a price based on quantity or type of product with no other input at all.

It is inconceivable to think that guessing at a price for a printed product is a reasonable pricing procedure. Nonetheless, it is a technique practiced today by those who believe that intuition is better than averaging when pricing printing or by those faced with an excessively large number of estimates to complete in a limited amount of time.

Basic Theory of Printing

Four-color printing:

Black can be obtained by mixing R, G and B color together according to a certain proportion, then why black color is still needed? Yes, because black is widely used in actual design, so it is not economical to produce black by three color inks in actual usage. This is why four-color printing appears. Moreover, black produced by R, G and B looks false, while black produced by direct preparation of ink looks stark. 1. Four-color principle is well accepted by people. It equals to four films in output, and cyan, magenta, yellow, black (C,M,Y,K) channels in Photoshop. When we modify the channels in image procession, we actually change the film. Mesh, dot, angle, flat screen and hanging screen. Mesh: dot number per square inch. Ordinary printed maters usually use 175 meshes; newspaper uses 60~100 meshes according to paper quality; special printed maters uses special meshes.

Dot: include round, oval, rhombi, square, diamond and frequency dot etc. The above figure is composed of round dots.

Screen angle: the included angle formed by the straight line linked by two closest dots and the horizon line. The angle in above figure is 45 °.

Flat screen: dots of the whole film are evenly and regularly distributed with the same size, which form a plane. The above figure is flat screen.

Hanging screen: dots are in different size. The screen has layers. The following screen angle is 60°.

What to do before outputting film?

I File Format

Most parts of input center adopt RIP (pspnt) output system and phototypesetting output systems like HQ510, Scitex of Israel, and Heidelberg etc. All of them support postscript press description files, i.e. files with suffix ps. Other file formats, which can be output directly by RIP, are: s2, s72, ps2 (Founder Bookmaker), EPS, TIF, PDF etc. Widely used design software currently is: photoshop、pagemaker, coreldraw, illustrator etc. All can produce a PS or PDF file through postscript virtue printer. Word, wps2000 and other word processing software can also produce ps files through postscript virtue printer. In fact, pre-press output shall go through some processions like making-up, adding register regulating line and cutting line etc. But word, wps2000 is incapable of such functions. For color script, it would bring great difficulty to do post-production processing after the script is done. Therefore, select pagemaker and a series of professional design and composing software as mush as possible.

II Format and precision of format

Offset printing (four-color overprint) is widely adopted in modern printing, i.e. divide color image into four colors: cyan (c), magenta (M), yellow (Y) and black (B) dot film, and print them down into PS plate. After 4 times of printing by offset printing machine, color printed product is completed. Images used for printing is different from ordinary computer-displayed images. The image shall be in CMYK mode, not RGB mode or else. Change image into dot during outputting, i.e. precision: dpi. The minimum precision of images for printing shall be 300dpi/pixel/inch in theory, but most fine images we see in computer are actually 72spi RGB mode. They are unprintable. Image cannot be selected simply according to its display effect. Don’t judge an image’s printability by seeing its effect through acdsee or other software. Open the image by Photoshop, and confirm its precision by image size option. For example: resolution of an image is 600*600dpi/pixel/inch. It could be used after being amplified to twice of the original size or more. If the resolution is 300*300dpi, it cannot be amplified, but can be minified or kept as the original size. If the resolution is 72*72dpi/pixel/inch, its size must be decreased (dpi precision would increase) till the resolution reaches 300*300dpi. (Define the “re-define pixel” as N/A in image size option in Photoshop). Usually seen image formats are: TIF, JPG, PCD, PSD, PCX, EPS, GIF, BMP etc. TIF multi-colored, black & white bitmap, EPS vector graph or JPG compressed format bitmap are the generally used image format by output software before printing. Choose the three formats as much as possible.

III Image Color

For overprint, lap-print, empty, spot color and other terminologies, and please refer to relevant printing knowledge. Here we only talk about some common knowledge. 1. Empty

When there is a line of blue words on yellow baseboard, the position of blue words shall be emptied on the yellow plate of the film, vise versa. If print blue directly on yellow, blue words would change into green. 2. Lap-print

When there is a line of black words embossed on red baseboard, the position of black words shall not be emptied on the red plate of the film. Because black can cover any other colors, if empty the black content, white margin would be produced in case of any error, especially for some tiny words. The margin can be spotted easily, because white and black are contrasted to each other. 3. Four-color black

This is a common problem. Before output, you must check out whether black words in publication files, especially small words, only appear in black board. They shall not exist in plates with other colors; otherwise, the finished product would be affected in quality. Black words would definitely turn into four-color black when converting RGB figure into CMYK figure, which shall be solved except specially designated before outputting film. 4. RGB mode image

When RGB mode image is output, RIP system would turn it into CMYK mode automatically, while color quality would be spoiled greatly, and the finished product of printing would show in tint and dim colors. You’d better change the image into CMYK mode in Photoshop. If it is scanning script, you must calibrate colors to make the image usable.

IV Precision of film hanging screen

Precision of hanging screen is called hanging mesh. Higher precision means finer product, while paper and ink also play important role. If images with higher hanging mesh were printed onto newspaper paper, images would become blurred very badly. Therefore, you shall know the printing paper before output, and then decide precision of hanging screen. Usual paper and hanging mesh precision: imported copperplate paper or self-adhesive paper etc---175~200 lines; imported offset paper etc--- 150~175 lines; ordinary offset paper etc—133~150 lines; newspaper paper—100~120 lines. Worse paper quality means lower hanging mesh, vise versa.

Conclusion

You shall pay attention to the following before outputting printed maters:

1. Select commonly used design software, like PageMaker. Don’t use Word.

2. Image mode must be CMYK; minimum precision shall be 300*300dpi/pixel/inch.

3. Check if words in publication materials are four-color words, if they are, change them into single-color 100% black.

4. When use PageMaker and illustrator, you must copy the linked image files and original files together.

5. Photoshop files are better to be psd (without layer combination) files in order to make modification easier.

6. Change words in CorelDraw or illustrator into Outline to avoid output failure due to inexistence of such typeface in output center. Copy inlays files together.

7. Inform the output center of product size, printing volume, used paper etc, to make make-up and screen hanging easier.

8. If content of two pages is the same, only black words are different (which is usually seen), you only have to output CMYK four-color of the first page and K color of the second page. This would cut cost. If there are only two colors (like red and black), and requirement on printing is not high, you may output them in a color plate at a time. There is no need to output them after separating them into two colors. Some treatment in printing plate making is necessary. It can reduce cost too.

Dot angle

Cyan: 15°, magenta 75°, yellow: 90°, black: 45° Screen dots are usually aligned regularly, so there are angle differences in application. In single-color printing, screen line angle usually adopts 45°, because dots printed in this angle is the most comfortable. It is not easy to spot the existence of dots, which would yield continuous grayish effect. In printing with two colors or more, you have to notice angle combination of two screens. Otherwise, unnecessary patterns would occur, called as “Moier”. Moier could be avoided by making angles of the two screens differ in 30°. Therefore, dominant color or deep color use 45°, tint color uses 75°, yellow uses 90°, cyan uses 15° and black uses 45°. There are no restrictions on these angles, which are subject to change upon requirement.

What is PostScript?

Postscript is a program language designed specially for figure and text printing. It is irrelevant to media. PostScript is suitable for printing on paper, film or for screen display. It is a page description language, similar to HTML language. PostScript is promoted by Adobe in 1985, being first applied in LaserWriter press of Apple. The major target of PostScript is to provide a language, which can describe image and is independent from equipment. Independent from equipment means not to rely on any specific equipment performances (e.g. press resolution) to describe an image. Therefore, the description can be printed directly in other PostScript presses without any modification. As a language, PostScript has a whole set of grammar and format regulations. Please go to Adobe website .http://www.adobe.com, if you are interest. You can find complete information there. PostScript files are stored in text, which is similar to HTML file. You only have to open a PostScript file by WordPad to see it. PostScript file uses Postscript language to describe characteristics and parameters of image to be displayed or printed. Detail printing or displaying are interpreted and conducted by PostScript interpreter to obtain needed image. Figure 2 is the display of PostScript file of figure 1 in PostScript file reader. You can see that the PostScript file has gain multi-color pages after being interpreted and displayed. PostScript files have many advantages compared with other format files. Aside from being independent from equipment, which is an important point, they are independent from operating system platform. Many figure environment of Unix regards support to PostScript as a part of the core functions. Both Windows and Unix operating systems can read and print PostScript files, which enables easy communication. PostScript file is stored in text format, thus it is small and suitable for transmission on Internet. What’s more, printing and displaying by PostScript equipments (press, monitor) have unique advantages and can achieve the best quality.

Methods for generating PostScript files:

(1) You may refer to language format of PostScript to write a PostScript file directly by text editor according to your need. You have to undertake big workload if the file is complex, and shall know PostScript language well.

(2) You can use special functions provided by PostScript file editing software or some other text and figure editing software to generate PostScript file.

(3) The simplest method is to add a PostScript press (virtue) in your operating system. In text editor or figure editor, the file you obtained by printing the image you need through PostScript press is the PostScript you need.

Common Problems in Printing

Issue 1: File saved in wrong formats/version
Save all illustrator files in version CS3 & above or high res PDF

Issue 2: Missing fonts
Outline the fonts. Dot not attach fonts when uploading

Issue 3: Save file in the correct colour mode
For CMYK prints, submit the artwork in CMYK colour. As PANTONE Prints, submit artwork in spot colour.

Issue 4: Missing link files
Embed all link files before uploading the file

Issue 5: Do not set overprint
Do not apply any overprint setting

Issue 6: Do not create lines which is less than 0.25 pts
Create lines which is more than 0.25 pts

Issue 7: Do not create black background with C=100, M=100, Y=100, K=100
If you need a ricker black, create C=60, M=40, Y=40, K=100

Issue 8: Colour tints is less than 10% difference
Set colour tints above 10% difference