The anodized aluminum plate

Litho stone has traditionally been regarded as the ideal lithographic surface for very definite reasons, because it is porous and able to readily accept both image and non – image areas equally. The printing from stones was obviously limited to the use of slow, flat – bed machines. To enable lithographers to use rotary presses a substitute plate, which could be wrapped around a cylinder, had to be found. Zinc plates were used for many years and later aluminium, but it was found necessary to grain the surface in an attempt to simulate the porous nature of the stone and thereby allow a minimum of water to be retained on the plate to give efficient damping to keep the non – image areas clean.

The use of grained plates is far from ideal. The grain structure tends to cause tonal distortion, resulting in the characteristic broken – edged dots. Their use was further complicated by their tendency to oxidise.

Aluminum has a natural oxide layer which improves its ability to retain moisture, but which sometimes causes a form of corrosion called oxidation.Plate maintenance and treatment to prevent oxidation could represent a considerable addition to machine time, particularly in the case of multi – colour presses.

It was because of these problems that the anodized aluminium plate was developed and introduced successfully onto the market in the 1950s. The anodizing process is of an electro – chemical nature, which encourages the growth of the natural oxide layer, under carefully controlled conditions, to produce the anodic film – 99.9 per cent pure aluminium is used.

The new metal is treated in a caustic solution which cleans it and magnifes any faults. The plate is then given a fine grain, usually by chemicals, and again immersed in the caustic bath to bleach it light grey. This colour allows the eventual image to be more readily visible.

The plates are placed in the anodizing bath which is lead – lined and filled with approximately 15 per cent sulphuric acid solution. The lead lining acts as the cathode and the aluminium plate as the anode. At 20 ^oC a low current is passed through the bath, oxygen is released from the solution and the natural oxide layer is encouraged to grow as an integral part of the plate. At first a barrier layer is built up and then a cell layer containing minute pores. The thickness of the anodic layer is about 3 microns.

When the plate is fully anodized it will not oxidise further and therefore stoppages for plate treatment are kept to a minimum, and plates do not have to be gummed - up for short stops. Anodized aluminum not only overcomes the problem of oxidation, but the anodic layer has lithographic qualities similar to litho stone. The capillaries in the non – image areas retain a minimum of moisture to give efficient damping, and with the smooth surface allow fine tonal reproductions.

The advantages of the deep – etch process can be combined with those of the anodized plate. The only variations being the use of suitable etches which open and enlarge the pores in the anodic layer to accept the lacquer base and therefore the image is virtually absorbed into the porous surface, which gives the plate a much longer press life.

By varying the voltage applied and the temperature of the anodizing bath the purity of the anodic film may be varied. Such a surface is available and accepts presensitised plate coatings. This has extended the range of presensitised plates, not only in length of run but in printing quality.

Multi – metals

Litho plates must have two distinct and opposing areas, called oleophilic and hydrophilic, which are formed on the one surface. Initially, lithographers observed that certain plates accepted grease far more readily than others, whilst others were more easily dampened. For example, the images on zinc plates tended to spread and thicken and it was once necessary to have a relatively course grain to retain sufficient moisture to keep the non – image clean. The reverse was found to be the case with grained aluminium – work tended to sharpen and a fine grain was used as water was easily retained.

Therefore it was logically assumed that if an oleophilic material could be used for the image and a hydrophilic one for the non – image an ideal plate would be produced.

Although more expensive than other plates the multi – metal is still relatively inexpensive when compared to other printing surfaces. The matt chromium surface of approximately 1,5 microns is hard and friction resistant and will not oxidize readily and therefore gumming up is not necessary for short press stops. Whichever multi – metal plate is used, they will give extremely long runs and prove to be efficient and require little damping to reproduce high – quality work.

The selection of a particular plate must be governed by several factors, the principle being: length of run, whether the job is to be reprinted, cost, and reproduction quality.

The quality of reproduction is also important. In this context it must be remembered that although it is possible to reproduce fine halftones on the plate, the plate is not the end product and must print well on the press. This is where the damping qualities of the non – image areas play a major part. Often a printer may select a more costly long run plate, such as anodized deep – etch or tri – metals which are capable of printing fine – quality work for a relatively short run but where a high standard is the key factor.

Oral Practice

Topic. Advantages and Disadvantages of Offset Lithography and Letterpress Printing.

You are all students of Graphic Arts Department. You’d like to get the idea about kinds of printing and technological processes used to obtain the finished product, the most magic miracle of all miracles in the world the name of which is « Book ».

I. Прослушайте или прочитайте информацию.

Letterpress is the oldest form of printing. This method was invented by Johannes Gutenberg 500 years ago. Letterpress is the most economical method of printing because it prints directly from metallic types. In the letterpress process the printing is performed by means of a raised surface: the type or blocks that are to be printed are raised above the non- printing areas.

Letterpress is used for printing of books, magazines, business forms, tickets and so on. Most of these products are not necessarily printed in letterpress but can also be produced by other printing methods. Letterpress uses a lot of image-carriers. They can be divided into metallic composition, different kinds of pictorial image-carriers which can combine type images with pictures and a number of different duplicate plates. Four kinds of duplicate plates can be used in letterpress; stereotypes, electrotypes, rubber-plates and plastic plates.

Electrotypes are the best duplicate plates. They are used for printing long runs with the highest quality and precision. Presses for letterpress printing may be divided into three groups: platen presses, flat-bed cylinder presses and rotary presses. Platen and flat-bed cylinder presses which can print from type forms are used for the production of shorter runs than rotary presses. Rotary presses can print much faster than platen and flat-bed cylinder presses and are therefore used for long runs.

Plane printing uses printing image-carriers on which the printing areas and the non-printing areas are in the same plane.

The principle of plane printing is based on the fact that grease and water do not mix. Non-printing surfaces receive water solution and printing areas must receive greasy ink and repel water. At present, offset lithography is the most important method of plane printing. It can produce many kinds of products. For example, books, magazines, newspapers, maps, package materials and so on. Offset lithography is an indirect printing method. In direct printing methods the printing image-carrier is inked and the resulting ink image is directly transferred, or impressed, into the printing stock where it becomes the printed image. In offset lithography the ink image is not transferred to the stock but applied to an intermediate surface called the blanket. From the blanket the ink image is then transferred again, now to the stock where it becomes the final printed image.

Numerous presses are used for offset printing. Some of them are made for printing of sheets and some – for printing of webs. Web presses are faster than sheet-fed ones.

II. Ответьте на вопросы, используя данные в скобках слова.

1.What kinds of duplicate plates for letterpress do you know?

(stereotypes, electrotypes, plastic plates, rubber plates).

2. What kinds of presses for letterpress do you know?

(platen, cylinder, rotary).

3. For what runs are electrotypes used?

(long).

4. What quality have electrotypes?

(highest).

5. What presses print faster: rotary or cylinder?

(rotary).

6. What kinds of production are printed by letterpress?

(books, magazines, business forms).

7. Where are printing and non – printing areas situated in plane printing?

(in the same plane).

8. What presses are used for offset printing?

(web presses, sheet-fed presses).

9. Where is the ink image applied in offset printing?

(blanket).

10. Where is the ink image transferred from the blanket?

(the printing stock).

III. Разделите текст на смысловые части.

IV. Озаглавьте каждую часть текста.

V. Сделайте короткие сообщения на тему «Высокая печать» по данным группам слов.

a. letterpress, invent, method of printing, use, print, produce;

b. image-carriers, divide into, duplicate plates, stereotype, electrotype, plastic plate, rubber plate, run;

c. rotary, flat-bed cylinder press, platen press, therefore, faster.

VI. Сделайте короткое резюме текста о высокой печати, используя выражения:

The subject of the text is……

It is necessary to point out…

Further I should like to say some words about…

VII. Ответьте на вопросы:

1. What products can offset printing produce?

2. What is the most important method of plane printing?

3. What is the principle of lithography?

4. Is offset lithography an indirect printing method?

5. What is the difference between direct and indirect printing methods?

6. What does the blanket serve for?

7. What machines work faster: web presses or sheet- fed ones?

VIII. Обменяйтесь репликами о плоской печати типа:

I think that…I suppose that….What is your opinion about…

IX. Составьте краткую аннотацию текста о плоской печати, используя выражения:

The subject of the text is…The text points out that….. It is shown that…The next part of the text is devoted to….The text also discusses….

X. Сделайте короткие сообщения о плоской печати, об офсетной печати, о машинах для плоской печати, используя данные группы слов.

a. plane, plane printing, grease, water, mix, printing, non- printing, surfaces, receive, repel;

b. indirect, ink image, transfer, apply, intermediate surface, blanket;

c. web press, sheet – fed press, print, fast.

XI. Выскажите свои соображения о достоинствах и недостатках высокой и плоской печати.

Lesson 3

Грамматика: Составные предлоги и союзы.

Основной текст А: Intaglio Printing

Составные предлоги

Упражнение 1. Переведите следующие предложения, обращая внимание на составные предлоги.

1.According to the information received by us the exhibition will open on May, 10.

2.The fisherman did not go into the open sea because of the storm.

3.All the calculations were made by means of electronic computer.

4.He achieved these results due to his hard work.

5.Inaddition to the oral examination they are given a written test.

6.The bus stop is just in front of my house.

7.I went to the post office in order to send a telegram.

8.I went on an excursion in spite of the rain.

9.May I go there tomorrow instead of today?

10. He could not go to work in the North on account of his poor health.

11. We could not get there in time owing to a severe storm.

12. The fire was quickly extinguished thanks to the energy of the fire brigade.

Составные союзы

Упражнение 2. Переведите следующие предложения, обращая внимание на составные союзы и предлоги.

1. Mу younger brother is as tall as I am. 2. I shall remember you as long as Ilive. 3. By means of this device we can carry out more operations now in shorter time. 4. The work is going on according to the time-table. 5. The new equipment was used in order to test the vibration of the engine. 6. You can get to that part of the city either by bus or by the underground. 7. The engine did not operate because of bad fuel. 8. He takes part neither in conferences nor discussions. 9. The monument was restored in spite of many difficulties. 10. The book is interesting as well as useful. 11. Thanks to his help we finished our work early. 12. We decided to cross the mountains so that we could reach the village before dark 13. Who can repair the apparatus instead of him? 14. As soon аs all the calculations are completed, we shall begin the tests. 15. In addition to the usual methods of computation they made use of computers. 16. Both the bridge and the tunnel will be finished in time.

Vocabulary notes

1. to sink (sank, sunken) – опускать (ся), снижать (ся), погружаться

On intaglio image carriers printing areas are sunken below the surfaces.

2. intaglio printing – глубокая печать

Intaglio printing is one of the classic methods of printing.

3. engraving – гравирование

Engraving is used for making intaglio image-carriers.

engraver - гравёр, цинкограф

The engraver works with a hand tool.

4. etching- травление

The plate surface is first protected for etching non-printing areas.

Etchant (mordant) – травящее вещество

The etchant attacks the base metal.

5. to dissolve – растворять (ся)

Mordant dissovles the base metal of the image – carrier.

6. to treat – обрабатывать

The image is treated by the etchant for some time.

7. to deposit- осаждать, давать осадок

Ink is deposited in different areas of the stock.

8. colour value – величина цвета

Colour value is varied to the final printed image.

9. to account for – объяснять

Variation of colour value accounts for the remarkable progress made by intaglio printing in picture reproduction.

10. flexible – гибкий, удобоприменяемый

Intaglio printing is a very flexible process.

11. versatile – многосторонний

Intaglio was so versatile that it developed method after method.

12. quill – перо (гусиное для письма и графики)

Sometimes an artist creates images with a quill.

13. brush – кисть

More often painters use brushes for pictures.

14. to duplicate – воспроизводить, копировать

It is very difficult to duplicate a picture of a talented artist.

16. line – штрих, линия

Intaglio methods developed from line to tone.

17. full – colour printing – полноцветная печать

Full – colour printing can be achieved by intaglio methods.

18. to accomplish – совершать, выполнять

Printmaking is accomplished by a slow, tedious process.

19. roller – валик

Ink is applied by hand or by means of rollers.

20. dabber – тампон

Dabbers are often used for inking plates.

21. to wipe – вытирать

Plate is wiped clean on its surface with a rag.

22. to pull out – вытягивать

Paper pulls out the ink out of intaglio cells.

23. minute – мелкий, мельчайший

The image carrier consists of minute cells.

24. shallow – неглубокий

Intaglio recesses are rather shallow.

25. recess – углубление

Colour value depends on the depth of image recesses.

Text 3A

Задание 1. Прочтите текст.

Intaglio printing is the name of a process family comprising a variety of printing methods which all use printing image- carriers with the printing areas sunken, or embedded, in the depth of the carrier material. Such images are technically known as intaglio as opposed to relief images. In relief printing the ink image comes about in a single operation which consists in applying printing ink to the top surface of the relief image carrier. This surface is identical with the printing image. But in intaglio printing things are quite different. Here the non- printing areas are on the top of the image- carrier whereas the printing image is sunken in the depth of the carrier material.

Printing image carriers for intaglio can be made by engraving, by etching, and by a combination of etching and engraving. The image carrier for intaglio is always a metal plate, usually copper, but possibly also zink or steel. The engraver works with hand tools that are much harder than the plate.

For etching the plate surface is first protected by an acid proof resist in the non – printing areas and left bare in the future printing areas. Then the plate is treated with an etchant, often called mordant, which attacks the base metal, dissolves it and therewith produces an intaglio image. The depth of this image depends, other conditions being equal, on the length of time for which a particular area is treated by the etchant. The longer the etchant can act on the metal, the deeper the image becomes.

Intaglio printing can vary the amount of ink to be deposited in different areas of the stock within the same press run: thereby is added a new feature, variation of colour value, to the final printed image.

This unique ability accounts for the remarkable progress made by intaglio printing in the art and technique of picture reproduction. Intaglio was so flexible, so versatile that it developed method after method until it became possible to reproduce- more or less faithfully by etching and engraving the images which were created by an artist with his pencil, quill or brush. What human hands originated, human hands were also able to duplicate. Step by step, intaglio methods expanded the art of picture printing from line to tone, approaching continuous tone or even achieving a kind of full – colour printing. All this was accomplished long before the invention of photography and photomechanics revolutionized the reproduction of pictures.

Intaglio plates for printmaking are printed on hand presses. As the ink must be very stiff, the plate is usually warmed prior to inking: the ink is applied by hand either with a roller or a dubber. Then the plate is wiped clean on its surface with a rag.

Inking an intaglio plate is far from being a mechanical operation. The appearance of the final print can be greatly changed by the manner in which the plate is inked. The paper must be dampened for printing: thereby it becomes limp and able to pull the ink out of the minute and shallow intaglio recesses of the image carrier.

Printmaking is slow and tedious business, and the number of prints than can be taken from a handmade itaglio plate is relatively small. But printmaking affords a satisfaction of its own to the practicing artist. For the printer, fine – art printmaking connects the industrial present with the handicraft past and with a great tradition of picture reproduction. Such famous artists as Duerer, Rembrand, Goya all made their own etchings, and so did many others.

Задание 2. Ответьте на вопросы.

1. What printing image – cariers are used for intaglio printing?

2. What is the difference between intaglio and relief images?

3. How can image carriers for intaglio be made?

4. What metals are used in intaglio platemaking?

5. How is etching of the plate accomplished?

6. What is the reason of the remarkable progress made by intaglio printing?

7. What method is used for creating intaglio plates?

8. What famous artists accomplished picture reproduction?

Упражнение 3. Переведите предложения, предварительно вспомнив, как переводится причастие I и II, а также независимый причастный оборот.

1. The research work done at this laboratory will greatly help the printers.

2. Working at the composing machine the operator must be very attentive.

3. The illustrations produced at this print shop are always of high quality.

4. Photocomposition being widely used in graphic arts, our country needs more specialists in this field.

5. The man showing the ingredients of the printing inks to the students is our engineer technologist.

6. Gravure plate has many cells of different sizes, some of them holding more ink than the others.

Упражнение4. Переведите предложения, обращая внимание на перевод герундия.

1. Printing in lithography is accomplished by applying ink and water solution to the specially treated areas of the plate.

2. You can’t develop graphic arts industry without developing photographic methods.

3. After making the impression the plate is inked again.

Упражнение 5. Переведите предложения, обращая внимание на составные предлоги и союзы.

1. According to the information the press meets the present – day requirements.

2. The operation of the press was unreliable due to the bad work of the printing unit.

3. The dampening of the plate was made by means of a special device.

4. As soon as you check whether all parts of the machine function well, you may begin the test.

5. The new plastic to be used for this purpose has to be both strong and elastic.

6. Because of frequent breakdowns of the press the task wasn’t carried out in time.

7. The more reliable the operation of the press, the better the results obtained.

8. Не works four hours every evening in addition to the work he does during the day.

9. Neither intaglio nor offset lithography are used for banknote printing.

10. They are going to start the construction of the new shop either this or next summer.

Text 3B

Задание 1. Прочтите текст, стараясь понять основное содержание. (Заметьте время начала и окончания чтения. Этот текст нужно прочесть за 5 минут).

Date: 2016-05-14; view: 558; Нарушение авторских прав