Polymetaal

A technical dictionary of printmaking, André Béguin. EN

I. DEFINITION AND HISTORICAL BACKGROUND

As a very approximate definition one could say that "paper is essentially, any thin and light sheet that is strong enough to receive and keep writing on it, the writing being applied with an instrument dipped in a coloured liquid. The sheet may be made with any kind of substance". This definition ol paper as a vehicle ol thought is due to E. Egger ("Le papier dans Pantíquité et dam les temps modernes", Paris, 1866) and includes all possible supports: fiber, leaves ol trees, skins, parchment, papyrus, etc. ln a more specific and also more contemporary way, it may be said that paper comes in sheet form end is made of a patchwork of vegetable fibers that are first reduced to a pulp and then spread, dripped, dried, and prepared lor use.
Paper is used as a support for both writing and drawing in manuscript form and for printing. lnsofar as prints are concerned paper is practically the only substance used with the exception of a very small amount of prints that are printed on other materials such as metal or then on cloth. lt is hardly a coincidence that both print making and printing in general first developed in connection with paper making.
The word paper began to be used in the 13th century. lt comes from the latin word papyrus which was used both for the plant and the paper made from it. The latin word came irom the greek word papuros which was the general name for the Egyptian reed.
According to some versions of the story the inventor of paper was Tsai-Loun who lived in China in the first century A.D. The most ancient pieces of paper are kept in the British Museum and bear Buddhist texts of the second or third century A.D. These pieces of paper were found in Eastern Turkestan. Chemical analysis of these fragments haver shown that they are made up of a mixture of berk and used rags (most of the latter being made of hemp). The idea that the first paper was made with the seeds of the cotton plant is no more than legend as the chemical analysis has shown.
Up until 751 the paper making process remained a Chinese secret even though paper had been exported prior to this date. After the battle of Samarkand a group of Chinese artisans were taken prisoners by the Arabs and made this town into a very active paper producing center. The extensive flax and hemp cultivations surrounding the town, which were well irrigated by a system of canals, provided the raw materials for this industry. The arabs, masters of the Middle East and the Mediterranean, became the chief exporters of this product and succeeded so well that soon after paper was to be found in Bagdad and Damascus. Then the paper route spread to Fez and from there crossed into Spain. As of the 11th century paper began to be known in Europe and in the 12th century it was being used in Montpellier, having passed through Cadiz, Sevilla, Cordoba, Toledo, Barcelona, Perpignan and Narbonne. The first paper made in Europe appeared in Spain in the 12th century. A century later paper began to be made in italy where the Fabriano works were set up. The first French works were those of Troyes (begun before 1348) and Saint-Cloud (begun before 1376). Then paper making began to spread to Northern Europe. The first German paper was made at the end of the 14th century near Nürenberg. in Flanders paper was made as of the 15th century.
Paper progressively took over the role of other writing supports such as papyrus (which, however, was never used for print making). Papyrus was currently used up until the 8th century but by the year 1000 had become very rare. From the 2nd century A.D. to the 15th century parchment was used and continued to be used for prints. This parchment was made from still born calves, sheep, or goats so that the sheet was not marred by any hair. Although it may be said that paper played a central role in launching the printing of books and pictures it must be remembered that it was not readily accepted in the past. Its "jewish-arabic" origin made it rather suspect in the declining Middle Ages and its relative fragility was such that legal documents could not be written on it. On the other hand, it must be said that paper was initially quite expensive and at times "almost as expensive as parchment". The increased amount of paper mills and the lowering prices of linen and! cotton cloth (which partially replaced wool) eventually brought about competitive prices and soon paper became very much cheaper than parchment. Furthermore, parchment became increasíngly rare, to the extent that it even became a habit to scrape off old texts in order to use the parchment for another one (the palimpsest). In any case, the paper made at first was quite different from what we know today, especially since this paper was often not very homogenous and because it was usually improperly laíd. But, despite this fact, during the 14th century one could buy twelve sheets of paper for the same price as one sheet of parchment. Because paper's lower price and improved distribution, this industry became very important. In fact, it even became necessary to control the commerce of paper as well as the use of cloth and old rope. This was particularly true in italy, where paper soon took over from parchment.
Up until the 17th century France was one of the most important paper manufacturers. The most unfortunate Revocation of the Edict of Nantes (1685) forced a great number of protestant paper manufacturers to leave the country. After leaving France these paper manufacturers resumed their work in Germany, England, Holland, and North America. ln leaving the country they had also exported their knowledge which was essential in an industry that relied upon the transmission of secrets from master to apprentice as nothing had yet been written on the subject ("L'art de faire Ie papier", by J.J. Lalande, was not published until 1765). lt might therefore be said that France participated-inadvertently and indirectly in the spreading of paper making throughout the world.
The use of paper is directly proportional to the expression and diffusion of ideas. On account of this direct relationship the 18th century saw an enormous increase in the consumption of paper which, in turn, forced the paper mills to enlarge and multiply. The manual methods still used at the time gave a daily production- per team of twelve workers- of about 2,000 to 3,000 sheets of average sized paper 45 x 65 (17.5 x 26 in).
In 1798 the Frenchrnan Louis Robert, an employee of the Léger-Didot paper mills of Essones, invented a paper making machine and got a patent for his invention one year later. This invention began the era of industrially made paper. The first machines made sheets of paper that were twelve meters long.
Then an English machine began to produce paper reels as of 1909. By the middle of the 19th century there were 200 paper making machines being used in France, as many in Germany, and 300 in Great Britain. These machines produced roughly 2 tons of paper per day which was the equivalent of ten vats in the hand made procedure.
As the consumption of paper rose continually it soon became impossible to get enough rags. The paper industry switched to wood, straw,alfa|fa, and reed fibers as of 1850.
Paper may be classified into two major categories: the first is hand made paper and the second is machine made paper. One can also classify paper according to the composition of the pulp used since the pulp may be made with rags, with plant fibers, or even with mineral constituents. This kind of classification is very important in print making, especially insofar as pure rag paper is concerned. Pure rag paper is used for the best quality prints because of its appearance and its quality, as it will last for many years.

II DESCRIPTION OF PAPERS

1. MANUALLY AND MECHANICALLY MADE PAPER.

Hand made paper is made only with pure rag pulp. Machine made paper, on the other hand, uses rags in a very slight proportion (0,05% of the European production) and relies much more heavily on wood fiber (94% of the total) and somewhat less on straw, alfalfa, and reeds (about 6%). ln order to make paper one must first reduce the raw materials to an homogenous pulp containing mostly cellulose fiber. The first paper pulps made were what we now call mechanical pulps. The rags were first sorted, then beaten and tom in vats (with continually renewed water) until they turned into a well washed pulp. Some paper mills such as Richard de Bas of Ambert in the Auvergne still use the traditional methods. This mill still makes paper the way it was made in the Middle Ages. Rag paper made in industrial plants is worked somewhat differently since the pulp is cooked for several hours in sodium bicarbonate.(soda)
Pulp that is made with other subtances than rag may be either mechanical or chemical pulps. Mechanical vegetable pulp was first made in 1843. The process called for grinding up the wood until is produced a first, very liquid, pulp which had to be washed, filtered, and, at times, whitened. The mechanical pulp is usually not used alone since it tends to age very badly. ln fact it soon turns yellow and cracks.
Chemical pulp is treated by a separation process which keeps the cellulose and eliminates the other substances (such as lignin) by dissolving them. For this reason chemical pulp produces a paper which is similar to rag paper and which is much more resistant than mechanical pulp paper. However, such paper cannot be of a very high grade. Mechanical and chemical pulps are usually mixed in order to improve the quality of the paper.
Both mechanical and chemical pulp are often bleached with oxydation agents (hydrogen peroxide and bleaching water) or then with reducers such as sodium hydrosulfite.
Once the pulp has been obtained it is possible to go on to the real paper making procedure. Whether this step is carried out manually or mechanically makes no difference since the goal is to produce a sheet using the fibrous particles that one suspended in a fairly large amount of water. ln order to do this the pulp is spread on a bed, on a wire mesh, or on a plastic mesh which will retain the fibres and will let most of the water drip through.
ln the traditional manual method the worker plunged his form into the vat. The form was, and still is, a wooden frame with brass wires (which leave the so-called wire marks on the paper) that rest on perpendicularly placed wires called the rib. A second wooden frame keeps the pulp in the form. The wire mesh can be used to fix the water* mark, which is a kind of design made with wires. The pulp in the form is already in sheet form but at first it is very damp and therefore it takes on the impression of the wires, the rib, and the water mark.
The paper maker must shake the form from right to left so as to finish the sheet of paper, since only this shaking motion will rid the pulp of excess water. The sheet of paper is then put in the coucher which, in turn, deposits the rather shapeless sheet of paper onto a felt. The sheet of paper is then covered with yet another felt. The same procedure is followed until a pile of one hundred sheets of paper has been made (each sheet being separated by a felt). Such a pile is called a post. The post is then put into a press so as to push the water out of the paper. The height of the post must be reduced by two thirds. The sheet of paper is "born" when it is taken out from between the felts and is spread by a wooden instrument. All that is left to do is to let the sheet dry.
ln mechanical paper making the procedure followed is much the same as the one just described except that the steps are mechanically accomplished. The pulp coming from the diluting or cleaning part of the machine goes into a vat where the homogeneity of the pulp is maintained by a constantly revolving propeller. After being purified, the pulp ends up in a vat from which it is poured, in a regular stream, through slits onto the fourdrinier part of the machine. The fourdrinier part consists in continous copper, bronze, or nylon wires that take on the role of the wire mesh in hand made paper. This part ol the machine might be several meters long and even as long as twenty to thirty meters, depending on the model. lt moves at a speed of 150 to 650 meters per minute.
The drip drying of the pulp is activated by suction or then by the so-called dandy roll. However, when the paper comes out of the wet end of the machine it is still very wet and thus it must be pressed and laid as well as being pressed by a polished roller to rid it of the wire marks. At this point the paper is already formed but it still contains 60 to 65% relative humidity. In order to lower the water content to an acceptable 5% to 10% relative humidity the paper goes through a drying mechanism which consists of hot rollers and a ventilation system.
The next step to be accomplished is the finishing of the paper so as to give it another aspect than the one it has when it comes out of the machine. The calendering system for example, finishes paper.
All that is then left to do is to roll the paper up on reels according to the paper sizes wished for.

2. THE CHARACTERISTICS OF PAPER.

A. PHYSICAL CHARACTERISTICS.

1. RECTO AND VERSO. A sheet of paper will always have two equal sides, one being the wire side and the other being the felt side. The wire side is the recto of a sheet whereas the felt side is the verso of a sheet. On low finish paper these two sides are quite different from each other since it is quite easy to see the wire marks (intaglio dips in the paper) that can sometimes be quite deep.
The recto side, on the other hand, might have a relatively coarse grain due to the felts used in making the paper. If the paper is very thin the recto might also bear wire marks which will be in relief. On finished paper these marks might have disppeared due to the calendering or else they might have another type of finish if the paper is goffered mechanically. Nevertheless, even the smoothest sheet of paper will still show the characteristic marks mentioned if you wet the paper. At times the two sides of a sheet of paper will be of a different colour but it is best to use paper whose sides are as similar as possible to each other since the results obtained in printing might otherwise be very different.

2. MACHINE DIRECTION. As the term indicates direction is only important in machine made paper. In fact, the pulp does not spread evenly on the wires because the speed of the wire bed tends to turn the cellulose fibers in the direction of the machine. This machine direction is practically perpendicular to the so-called transversal direction. In laid paper it is easy to recognize machine direction since the wires are transversal and the warp, which is further apart (about 2.5cm = 1in), is in the machine direction. On the other hand, if the paper is not squared (i.e. if the border is not cut at right angles) the deckle of the paper will show the machine direction since it is where the pulp got to when poured into the wet end of the machine. If the paper is squared and has no wire marks it is quite difficult to figure out the machine direction. Usually the manufacturer indicates the machine direction of such paper on the ream but not on each individual sheet. At times it is important to know the direction, especially when printing on a mechanical press since picking up the paper transversally might cause problems.
Machine direction can be figured out in various ways. One way is to rip a sheet of paper as it will tear more cleanly in the machine direction and with a more jagged rip transversally. If you place a 10 cm (4 in) high pile of paper in a basin of water the paper will roll up in the machine direction. Yet another trick consists in cutting two strips of paper (15 x 1cm = 6 x 1/2 in), making sure that they are cut in the two possible directions. Then try to make them stay horizontal placing first one and then the other below the second. The one that bends more is the one that is transversal to the machine direction. If the two strips are dampened the difference is, yet more noticeable.

3. THICKNESS. This characteristic of paper must not be confused with weight, nor must it be confused with the opacity/transparence of the paper. In fact, thickness can be due to a given quantity of pulp but it can also be due to different amounts of pressure being applied in the making. Because of this a thick piece of paper can be either densely or loosely packed. Quite obviously the thickness of a sheet of paper is directly proportional to the volume the paper will occupy when piled up.

4. WEIGHT. The weight of paper is a very important indicator. In Europe the weight of paper is indicated in terms of grams per square meter (the substance). Paper that weighs less than 40 g/m² is considered to be thin paper. In this category are air mail paper, bible paper (India paper), glassine paper, etc. The most currently used papers go up to 80 g/m² whereas the best quality paper goes to 224g/m². Above 224 g a paper begins to be considered cardboard. In France the substance of paper has been normalized to the following types:

medium quality paper: 64, 72, and 80 g

high quality paper: 90,100, 112, 125, 140, 160, 180 g

The tollerance allowed for in French law is of +/-2.5% up to 120 g/m² and +/-4% up to 224 g/m².

The variations in weight are due, above all, to the water content.
The substance of paper allows one to calculate the weight of a ream of paper according to the paper size. The following table gives the weight in kg of a ream of 500 sheets according to the various paper sizes commonly used.

5. VOLUME. As we have already mentioned the thickness of a sheet of paper is directly proportional to its volume. Depending on the thickness and the weight of paper one can have a variety of quantities in one pack. A quire contains 21: sheets of paper, a long ream 500 sheets, a short ream 480 sheets, etc.

6. CUTTING. The size of a sheet of paper will be due to the form used in making it if the paper is hand made. lf it is machine made the paper size is determined by cutting. Usually hand made paper comes in average sizes, the reason being that the forms used are usually handled by only one worker at a time, thus both the size and the weight are limited for practical reasons. The edges of hand made paper are not squared. Their deckle* edge is due to the fact that their edges are not clean cut. ln fact, the pulp spreads out on the form and is eventually stopped by the frame but not in an abrupt way. The deckle edge is also found on machine made paper but only on the two sides that are parallel to the machine direction. Machine made rag paper is left with its deckle edge and even the transversal cuts are usually somewhat uneven in order to imitate the deckle edge of hand made paper.
lf the four sides of a sheet of paper have been cut the paper is said to be squared. Paper can be squared on only one corner, in which case only that corner is perfectly right angled, or then it can be squared on all four corners (all four corners being right angles). Machine made paper can be cut either in the machine direction or then transversally.
Please turn to the article on paper sizes for a description of the different sizes in use. It might be remembered, however, that a certain latitude is left in size matters since they may vary by +/- 0.5% up to a maximum of -2 mm or + 3 mm for any size paper that is not squared on all four corners. This latitude is measured at a relative air humidity of 60% to 65% and at a temperature of 2D“C (68“F).
Finally, paper can come in reels whose width and volume (and thus weight) differs. The reels are used in rotary presses.

7. APPEARANCE. ln speaking of the appearance of paper we include its relief, its shiny or mat finish, its colour tone, its opaqueness or transparency, and its rigidity or suppleness.
A sheet of paper will have a particular relief - its grain* - which might be very regular or then irregular, fine or coarse, etc. The reason for this is that the paper will have picked up marks from the wires, from the felt, or even from the roller surface that was used to finish the paper. Paper that has no grain and that has not been finished is called vellum paper because its soft looking aspect reminds one of the parchment of the same name. The paper coming out of a paper making machine is called unfinished paper and must be finished by a calendering operation that is carried out on both sides of the sheet of paper. Some sheets of paper are calendered on only one side, in which case they are called friction glazed paper.
The glossy finish of a paper is due to the calendering it underwent whereas a mat finish is due to a lack of calendering. However, as we shall see further on in the section on the chemical characteristics of paper, the glossiness of paper can be accentuated by coating, which is an addition of a fine glossy layer. Calendering is done in order to ready paper for fine impressions and to supress its abrasiveness which is particularly bad for offset printing. Calendered paper is also less sensitive to dust. The degrees of calendaring go from smooth finish paper to glazed and supercalendered.
Untouched rag paper is creamy in colour. Other types of paper that are left as is are called unbleached paper. The bleaching of paper is an important step in paper making because very often the whiteness of a paper is associated with high quality. The whiteness of paper is measured on a scale that goes from 1 to 100 (fresh magnesium oxyde being equal to 100). According to this scale a very white paper will range anywhere between 88 and 92 whereas an off—white paper such as newspaper ranges from 66 to 66. Unbleached paper may rate as high as 30 but this is about the limit for unbleached papers.
The bleaching agents used are chemicals that will whiten the paper pulp. Recently another kind of "bleaching agent" has come into use, the so-called optical whitening agents which are fluorescent products which absorb the ultra-violet rays contained in the light shining on the paper. The problem with these products is that the colour of the paper varies according to the type of light shining on it. The other colours used in papers are simply colours that are mixed into the pulp.
The opaque and/or transparent qualities of paper are, of course, related to each other and are due to both the quality and the quantity of pulp used in making a particular paper. It is possible to measure the degree of opacity of a paper by means of a diaphanometer. It is most important that a sheet of paper be opaque if recto verso impressions are envisaged. When a sheet of paper is looked at in transparence one can judge the quality of the paper and the homogeneity of the pulp used in making it. To a certain extent one can also determine the contents of the pulp used. The quality of paper seen in transparenc is called the formation of the paper.
A sheet of paper can also be judged by its rigidity or, conversely, by its suppleness. This characteristic is due to the contents of the pulp but also to the coating that has been applied and to the finish. The rigidity of paper is not quite the same thing as its degree of hardness since the latter simply means that it is more difficult to damage the surface of such paper.

8. RESISTANCE. Different kinds of paper will be found to resist compression in varying degrees.
The elasticity of paper is valued above all for folding and for intaglio printing. Furthermore, it will be found that papers vary in their resistance to traction and will rip at different amounts of traction. The term breaking length indicates the length of a strip of paper, held at one end, at which point it will rip on account of its own weight.
Resistance to scraping and rubbing are necessary qualities in papers that are used for drawing on.
Finally, one may speak of a paper's resistance to destruction, a quality that allows the sheet of paper to resist more or less well to the effects of light, dryness, and humidity.

9. ELECTROSTATIC SENSITIVITY. The magnetization of paper is a phenomenon that will make it stick to another sheet of paper or even to another surface such as a silk screen. This magnetization phenomenon appears in excessively dry paper or then may be caused by rubbing paper.

B. CHEMICAL CHARACTERISTICS.

1.PULP INGREDIENTS. Paper pulp may contain a certain amount of constituents such as raw materials, fillers (load), gums and resins, colouring matter, and synthetic materials. ln some cases various other constituents are used such as leaves, flowers, etc.
The raw materials used are subject to a classification set up by the French norms for the paper industry.
These norms give a good summary of the components of various types of paper (Norms 000-001 promulgated on the 31st of December 1949).

Massive additions of synthetic materials to traditional paper pulp is a recent affair (such as the "Pulpex" of the Solvay Company, see further on at Ill, 1). These materials confer entirely new properties to paper.
The fillers or load are materials that are reduced to powder form which have a bleaching function and allow one to augment the volume of the paper pulp at a low price. Kaolin* is a type of load that is very much in use.
Gums, on the other hand, are used to improve the pulp. The most often used is starch (a vegetable glucid that may be considered a gum), gum adracanth, and yet other gums.
Resins, are used in paper making for sizing paper which must not be penetrated by watery substances (watery inks, baths, etc.). The most ancient sizing was carried out using animal glue until colophony came into use in the middle of the last century. Sizing is now done when the paper is stacked by adding a "soap", a reaction of the resin to the caustic soda or the resin-paraffin emulsion*. At times surface sizing is also practiced.
The colours used in paper making are introduced when the pulp is being made. The special additions found in some papers are also added while the pulp is made (for example, the fern and flowers of the Richard de Bas hand made paper).

2. COATING. A clear distinction must be made between. the sizing of paper, which as we have seen consists in adding a resin to the paper pulp in order to make the paper more or less resistant to water, and the coating which (as the term suggests) is a superficial application of special ingredients.
In the beginning of the 19th century paper began to be hand coated (with a brush) sheet by sheet.
This was done in order to regularize the surface of the sheets of paper, to make them shiny or even to give the same colour. At present the coating procedure is mechanically done and gives papers that are used for very fine printing or for printing very shiny colours. Furthermore, coated papers ensure a better ink penetration thus improving the drying* process. A sheet of paper can be coated either on one side (one-sided art) or then on both sides.

3. REACTION TO HUMIDITY. The reaction to humidity is very important. Any kind of paper must always have a residual humidity oi 5 to 10%. ll, due to atmospheric conditions, the paper becomes damper than this, its rigidity will diminish and it may begin to mould. lf the humidity goes below such percentages the paper will become brittle and turn colour. The correct humidity for storing paper is 7% which, at 18°C (6li“F), means that the relative humidity of the air should be 65%.
On the other hand, many types of paper used in print making must undergo dampening and even being soaked. The paper used for such purposes is made of rag, has very little sizing, and is, above all, uncoated.

4. ABSORPTION, PERMEAB|LlTY,AND POROUSNESS. Paper is more or less absorbant due to the very nature of the pulp used, even though it might be sized and coated. in other words, all papers are able to absorb, in varying degrees, a certain amount of oil or water. Permeability, on the other hand, refers to the extent to which paper lets a liquid through from surface to surface. Too great a permeability will cause show through, which means that an impression can also be seen on the other side. The porousness of paper is related to its fibrous structure which may be closely or widely spaced. This structure is responsible for the degree of permeability to air and liquids.

5.AClDlTY. All papers contain a certain amount of acid materials which, however, must not exceed more than a given amount since an acid paper tends to take longer to dry. Slow drying is particullarly problematic when printing on a mechanical press. Usually uncoated paper is more acid than coated paper.

III. THE PAPERS USED IN PRINTING

Generally speaking one can make a distinction between paper that will allow, when printed, for a relief, due to the plate used in printing (intaglio plates) and the paper that is used for printing planographic work. The former is taille—douce paper. This paper will bear the "plate mark" and will be pressed into the intaglio lines of the plate. ln fact, all of the papers which are used for embossing or goffering belong to this category. Taille-douce paper must be used when damp and must bear up under the dampening and soaking procedures. The second type of paper, which is used in planographic work, serves the purposes of lithography, serigraphy, offset and, to a certain extent, woodcut.
These two categories of paper must also be analysed in terms of their receptiveness to printing and, finally, in function of their quality since very often prints require paper that will enrich their appearance.

1.PAPER FOR ENGRAVINGS. The paper used for printing engravings must always have specific characteristics, above all, because it is compressed by the press and will only print correctly if the paper penetrates the lines of the plate. This paper mustytherefore be very elastic. it must take well to being compressed and have an homogenousness and a fairly strong body (i.e. a fairly low density in comparison to its mass). The paper surface must be soft to the touch but it must not be finished nor, above all, must it be coated. In selecting a paper to print on, the printer must choose in function of the relief he will need as determined by the plate to be used. Quite obviously finely etched plates will not require the same kind of paper as a deeply cut engraving. Fine etching requires soft, silky, and light paper whereas engraving calls for a heavier, more resistant, and elastic sheet of paper. Furthermore, one must bear in mind the thickness of the plate itself since a one millimeter thick plate (0.039 in) can easily be absorbed by light laid paper, but if the plate is thicker one must have recourse to a thicker and more resistant sheet of paper. The smoothness of the paper to be used must be chosen in function of the type of lines to be printed. Very fine lines must be printed on a very soft and homogenous surface such as a satin finish laid paper. Thicker lines can be printed on slightly grained paper.
Wide lines that are not very deeply cut require supple paper since a stiff paper will not pick up all of the ink out of the lines of the plate. Suppleness, elasticity, compressability, and satiny finish are all characteristics of rag paper (called laid paper) weighing from 100 to 300g/m’. If very deep goffering or stamping needs to be done only a heavy, strong paper can be used such as thick rag paper or corrugated paper weighing up to 600g/m’ (such as the "esportazione" paper of Fabriano or the "extrarugueux" of Arches). One may also, however, use extremely malleable papers treated with "Pulpex" which resist all kinds of manipulations and take particularly well to hot stamping.
Paper used for printing engravings must be very absorbant, permeable, only slightly sized and never coated. This is because engraving paper must often be dampened in the printing process. Their wettability* must be such that they will resist traction and compression when damp, and that they will go back to their former state after drying. it is not absolutely necessary that the paper be very thick but the pulp used must be well mixed. Pure rag paper is the paper that will take best to dampening. It might be mentioned that rice paper, Japan paper and some Dutch papers (in particular the Van Gelder vellum paper for intaglio printing) are extremely absorbant and therefore should be dampened with a sponge.
The new types of paper containing pulpex can, on the other hand, be used for intaglio printing without being dampened even though they take well to dampening.
Since the paper used for printing engravings must show up colours without artefice or brutality it is best that it be of a natural white colour not unlike the creamy white of linen or cotton. The different whites obtainable in rag paper are subtly varied and thus the printer will have to choose the tonality best suited for the engraving to be printed.
Paper used to print intaglio plates must not be subject to alterations or degradation. Because of this it must be made from a rich pulp containing a high percentage of rags. ln fact the rag content guarantees resistance to the adverse effects of light, humidity, and dryness.
Since this type of paper is usually used when printing with traditional inks containing linseed oil it is necessary that the paper be absorbant without, however, letting the ink show through. Mat finish, satiny, and slightly grained papers must remain permeable.
Moreover, it must be pointed out that the paper used for printing intaglio work should be "beautiful paper" because a print is not iust a reproduction but rather an original creation. A nacre finish Japan paper, a satin finish laid paper with a deckle edge, or a creamy vellum paper add much to an engraving‘s beauty. ln fact, it is hardly exaggerated when a specialist admires beautiful margins or a water mark that takes up the entire sheet of paper.

2. PAPERS USED IN PLANOGRAPHIC PRINTING. Although this paper does not have the same characteristics as the papers used in printing intaglio plates it must still be chosen in function of certain criteria. First of all planographic prints always turn out best when printed on high quality paper. This is due to the durability of such paper, as we have already seen. It is also a good idea to use a rag base paper or then at least some type of paper which contains a high proportion of rags.
These papers can be classified in two broad categories: deckle edge papers that are either hand made or then unsquared if machine made and, on the other hand, squared paper. Only squared paper can be used on mechanical presses especially when several colours are printed and registering* becomes necessary. ln fact, dekle edge paper cannot be properly registered on an automatic press. Nevertheless, deckle edge paper can be used perfectly well for printing woodcuts, lithographies, pochoirs, and monotypes if the printing is done manually, either by rubbing or with a traditional lever press. ln serigraphy one can use deckle edge paper if no registering is required. lf colour impressions are to be made the sheets of paper will have to be squared in order to superimpose the colours precisely. For offset work, lithographic work on mechanical presses, typography, automatic serigraphy, etc. the sheets of paper must be squared. At times it seems a real shame to cut the deckle edge of a beautifully made sheet of paper but it is important that the paper catch well when it is printed on.
The paper used in lithography must be absorbent in order that it take on both the oily inks and the water. Usually such a paper has a mat finish which is not at all fluffy. it should also have a very even satin finish since a grain that is too pronounced will refuse solid colour applications and may damage the half tone areas. In the past litho paper was laminated after‘ being dampened so as to polish the surface. This kind of work was done sheet by sheet between two polished zinc plates. After this calendeering the sheets of paper were pressed in packets of 25. ln chromolithography the sheets were calendered in order to give the greatest possible precision in registering. Coated and sized papers were much used in commercial lithography as well as simili Japan paper, which is smoother and more rigid than real Japan paper (the latter being preferred for quality work). For map printing a special type of paper was used which was insensitive to humidity.
In offset printing the paper used must be both well squared (in the direction of ‘the machine ) and very flat. Furthermore, such paper must have an average humidity when used and, although it must be absorbant, it must not be porous. Actually the more absorbent varieties of paper are not the ones that are more permeable on the surface. The "chromecoat", for example, is extremely smooth and yet very absorbant while blotting papers are less so. This is due to the fact that the capillary action of well laid paper is finer but greater and thus is takes an ink more readily than other papers. Offset paper must not be magnetized nor must it be very acid.
in serigraphy the levelness of a sheet of paper is a fundamental requirement. An irregular surface or a surface that is too grainy will cause problems in printing. The paper is chosen in function of the type of ink to be used (a great variety of them are used in serigraphy 1 ). Water base inks require a thick paper, very slightly sized if not at all, which must in no way be coated. The paper must be capable of good absorption but must also dry without being deformed. The papers used for oil base inks should be chosen in function of the effect to be obtained: absorbent mat finish paper will give a mat finish whereas heavily sized smooth paper which is also coated will result in a shiny finish. Shiny inks must be printed on shiny papers.
Very heavy, thick paper or cardboard must be extremely level and smooth if they are to be used in any one of the above printing techniques nor must they be excessively sized.

IV. SPECIAL PAPERS USED IN PRINT MAKING

1. PAPER FOR DRAWING.

The title of this section is "paper for drawing" rather than "drawing paper" because, in print making, there is a large use of supports, classified as "special papers", which are not necessarily the same as traditional drawing paper. Therefore l am using the term paper in a rather general way and hence the reader should not be surprised if l speak of supports that are quite different from pulp paper itself.
Drawings can be done on a great variety of supports but the most usual support is, of course, drawing paper, used either as the model from which a drawing is copied onto a plate or else as an original that can be copied photographically. Drawing paper can be of various sorts but essentially there are two types: one is generally used for "dry" techniques (pencil, pastel, chalk, carbon, etc. ) and the other is used for "damp" techniques.(ink, water paints, etc. ). The papers used for dry drawing techniques usually have a fairly pronouced grain depending essentially on the delicateness desired in the lines. Laid paper is well suited for crayon, charcoal, and stone drawing. Among the laid papers Ingres paper may be used for the crayon* manner in coniunction with a soft ground. It is also possible to do crayon drawings on soft, smooth paper on condition that it has a mat finish. The paper used for wash drawings is, of course, heavy and well coated, but it may be either mat or smooth finished. The paper used for water colour work is rather thick rag paper with a pronounced grain. However, it is up to the artist to choose the paper best suited to his kind of drawing technique (fine and precise lines, faded lines, thick lines, slight washing, gouache work, black ink drawing, etc. ).
Process paper (papier procédé ) was also called "Gillot's paper" (the inventor of the gillotype*process) and was much used in the 19th century for the rapid illustration of newspapers, periodicals, and even books. This paper‘is a kind of slight cardboard which has undergone gauffering* from a finely lined steel plate. The paper used for this purpose is also pre-printed so as to bear a uniform shading perpendicular to the gauffering itself. This permits the person doing the drawing to use a "screen" (with crayon and scraper ) in order to bring about, without much work, all the half tones needed.

2. TRACING PAPER.

Under this heading belong both tracing* paper and transfer paper the latter of which allows one to transfer a drawing from a sheet of paper onto another sheet of paper, a stone, a metal plate, or even a wood block. A whole variety of tracing papers are used which may be of varying weights (anywhere between 40 and 190 g/m² ), although the most common vary from 40 to 100 g/m². The so-called "mica" variety is the most transparent, but there are also thicker kinds that are more stable and can be scraped more easily. Tracing paper comes either in sheets or in rolls. Polyester tracing paper presents the advantage or perfect size stability. Because of this it is used for archive work and for drawings that have to undergo several manipulations or exposure to extreme humidity or dryness. The lines on this kind of tracing paper are, however, rather delicate and as a result it is best to powder polyester paper with some talc (a slight powdering will do ) and to use special inks and crayons for tracing.
Corrections must be made with a soft eraser or a glass fiber scraper. it is also possible to wash the surface with some soapy water. Tracing paper is also available lined like graph paper (Canson).
Gelatine tracing paper, a transparent sheet of paper covered with a layer of gelatine, was mostly used in the 19th century. The way it was used is as follows: first it was drawn upon and then the lines of the drawing were cut with a dry point. The next step was to fill the furrows with litho ink or with red chalk. The drawing could then be transferred by pressing it unto a stone or onto a metal plate.
ln serigraphy a wide use of transparent supports is made for photographically prepared screens. These transparent supports can be considered to be somewhat like tracing paper. Actually these supports are transparent, translucid, smooth, or variously grained sheets. They are drawn on with lndia ink, gouaches, or then with a special pen. The grain of these sheets allow one to obtain half tones that are not unlike the ones obtained in the above mentioned process papers. The transparence of these sheets allows for a perfect registering of each colour. All of the sheets are. then transferred photographically onto a screen. The artist making a silkscreen print can thus work with an original drawing. These transparent supports come either in sheets (40 x 50 cm = 16 x 20 in ) or in rolls [* serigraphy]. It might be added at this point that the screen used in serigraphy is, in itself, a transparent cloth and thus can be used for tracing if the original is placed below it.
In lithography transparent transfer paper is sometimes used for tracing (see further on for more details). Tracing cloth was also used in the past. This cloth was prepared on one side (usually the mat finish side ) or else the smooth side was pumiced and covered with sandarac before being drawn upon.

3. LITHOGRAPHIC PAPERS. .

There are two types of special paper that are used in lithographic work: transfer paper, which is used as a support for a drawing that must be transferred onto a litho stone or a lithographic metal plate, and so-called stone-paper, which is meant to be a substitute for litho stones or plates.

A. TRANSFER PAPER. Actually two different types of transfer paper are used. Autographic paper is used to draw or write on with autographic ink whereas transfer paper proper is drawn on with litho ink or litho chalks. In any case both are used for transferring. If more detailed information is required concerning their use consult the article on lithography (ll, 3, B ) and also transfer.

B. STONE PAPER . I have already discussed this type of paper in the article on lithography (l|, 1 and lll, 1) along with some other abandoned processes. In fact, it would seem that the "papyrographic" experiments of Senefelder, Knecht, and Kuhlmann were never continued. However, l did not know, when writing the entry on lithography, about paper lithography and the "litho-sketch master" invented by Anthony Ensink of Chicago which was used as a simple reproductive process by the American Army. This kind of paper is now distributed in Europe. It is very easy to use. First one draws on its surface with a special pen, then one proceeds to desensetize the plate with a special solution. This paper plate is dampened (with cotton, for example‘) before inking. Printing can be done with an instrument as simple as a spoon or then with a regular press.

4. PHOTOGRAPHIC PAPERS.

These light sensitive papers are made of a layer of paper and a photosensitive layer. Various types of photographic papers are in use at present:

- Positive photographic paper is meant to receive the final proof of a photographic image, using a negative as an intermediary.

- Negative paper is used in an economical line drawing process. The photosensitive layer of this paper can be transferred to make a copy on another support.

- The so-called industrial or gravure papers can take on an image from a negative or a- translucid positive. Two types were in use: ferro-prussiate paper and diazotised papers.

- Transfer papers are used for making positive or negative copies on metal, stone, or wood, at which point the block or plate can be worked either manually or by mechanical and chemical means.

Among the industrial papers the oldest ones are the ferro-prussiate or blue print papers which were invented in the middle of the last century. At present, however, this type of paper has been practically abandoned. It was much used in reproducing technical drawings as well as for typographic and photolithographic work. The non-protected areas (those that were not protected by an opaque black ) turned blue which meant that the image would be inversed if a positive tracing was exposed.
The industrial papers used today are diazotised papers. These give a positive image from a translucid or transparent positive. In fact the unexposed areas turn brown whereas the exposed areas are destroyed by the light shining onto the paper.
Yet another type of transfer paper is that with a gelatine layer. This paper was once much used for transferring images onto litho stones or metal plates. It consists of a very thin sheet of paper covered with a layer of gelatine. After being made photosensitive with a bichromate it is dried and exposed to light under a negative. The sheet is then dry inked and the gelatine is removed with water. The transfer itself is then brought about by pressing the gelatine sheet onto whatever support is to be used.
Positive paper, which is treated with a silver bromide and gelatine mixture, is used in much the same way as the above. It can be used to make a positive image and a reversed one.
Insofar as concerns transfers for intaglio techniques, the pigment paper or carbon paper used in photogravure is sometimes used. In the past the pigment used in making such paper was lamp black or ivory black, which explains why this paper was called carbon paper (and still is at times ) although other materials are now in use. The pigment is mixed with the gelatine bichromate so as to limit the penetration of light at the time of exposure. The photogravure technique requires a progressive hardening of the gelatine, quite the contrary of what is required in planographic or relief techniques, which only require differentiation between exposed areas and the non-exposed ones. The pigments most commonly used at present are red chalk and gum tragacanth, both of which are red and thus contrast well with the etched areas [* photogravure ].

5. PROTECTIVE PAPERS AND PAPERS FOR WIPING.

In the making of prints one often has recourse to a variety of protective papers as well as to various types of paper for the purpose of wiping.
ln make-ready procedures and in setting off printed materials one often uses tissue paper, sometimes called papier serpente in French because, in the 17th century, this paper usually bore a water mark representing a serpent. This paper was also used to protect engravings in books. Tissue paper is very light and may range anywhere from 15 to 30g/m² lt is translucid and is more or less calendered so that it is more or less absorbant. Tissue paper is also used for making flongs.

I have suggested repeatedly that intaglio plate wiping be done with tissue paper rather than with the palming* or paumage technique. This wiping should be done with the best quality tissue paper which is not absorbent and which is prepared the same way on both sides [* aquatint, wiping ].

6. BLOTTING PAPER.

The best quality blotting paper is made with rag pulp and, because of this, it is very absorbant.
Rag pulp blotting paper is used to dry printing paper (after letting the excess water drip away ) just before the actual printing is done. It is also used to dampen paper slightly for printing, but in this case it is placed between every five or six sheets of paper in a pile. Blotting paper must never be sized, laid, or finished in any way. lt usually weighs between 80 and 200 g/m^2. These are also lower quality blotting papers made with resinous pulp that can be used lor ordinary drying procedures. Blotting paper is also used in stereotyping* for the making of the flongs.

7 . CARDBOARD .

Cardboard is used in many different ways in print making. l have already mentioned the fact that papers weighing over Z24 g/m² are considered to be cardboard, but a distinction must be made between those made with high quality pulp and those that are made from inferior quality pulp (straw ) or with old newspapers. The latter can weigh up to 4500 g/m² and be one cm thick(one or several layers).
Laid cardboard weighs anywhere between 300 and 600 g/m² and although it is used for commercial printing it cannot be used for print making. Cardboard made with high quality pulp (the best being rag pulp) is used for printing covers, for stamping, for gauffering, and for quality book binding.
[* abrasives, adhesives, paper size, dampening, support ].