Irreplaceable paper

The Chinese held that paper was the first of four great inventions, followed by the compass, gunpowder and printing. Although it is easy to say paper, it is less easy to talk about it and to understand how to choose the right one for the project you want to carry out from the thousands available. From glossy, natural, recycled, eco-friendly, pulp-tinted, creative, special, extreme... here’s a brief guide to orient yourself.

By Lorenzo Capitani | On PRINT #83 | Versione Italiana

We never think about it, yet paper is always with us. And it has been since at least 105 A.D. when the Chinese court official Cai Lun first described its manufacture with “tree bark, hemp, shreds of cloth and fishing nets”; or perhaps since even earlier than that, from the middle of the 2nd century B.C. when the first archaeological findings of paper in the Chinese city of Dunhuang in Gansu date back to. Curiously enough, as Mark Kurlansky (author of Paper, Bompiani, 2016) claims, paper appears to be “an unlikely invention: reducing wood or fabric to its fibres, diluting them in water and passing them through a sieve to form a sheet is not a series of logical steps, so to speak, unlike printing which several societies arrived at independently more or less at the same time.” In the beginning, Europeans didn’t even know what to do with it, and it took more than a thousand years and the study of the Arabic arts of mathematics and science for them to abandon parchments and papyruses. Although we are in the midst of digital civilisation, paper today remains the most widespread material with an annual world production of 420 million tons. There is no area in which there is not at least one paper alternative: VDP, the association of German paper mills, estimates that there are more than 3,000 types of paper on the market. Paper can be seen in terms of its use and reuse for objects, but also as a communication vehicle. Apart from books and newspapers, paper is used for citrus fruits and fabrics, electrical insulation for condensers, absorbent cloths, filters, cosmetic substrates, upholstery, tableware, cases, packaging, stationery and a thousand other things. And today, Personal Protective Equipment in these times of the COVID-19 emergency is also made of paper. Gruppo Cordenons and Fedrigoni have developed a new virostatic paper for the production of masks from paper meant for food filtration, while the Mondi paper mill has converted its Gronau plant in Germany to produce laces for masks from its baby diaper production line. Without claiming to be exhaustive, we would like to start our journey from here by retracing the boundless world of this material which, made up of some essential elements such as cellulose, wood pulp, bleaching agents, adhesives and various chemical substances, can take on new shapes and surprising characteristics. The intention is to have a small guide, which is certainly not exhaustive, to keep under the desk, like a cheat note for an exam.

Coated
Gloss or matte: it all starts from this simple distinction. It’s the coating that makes the difference. A thin veil with a watery loss -  the patina - consisting of pigments (mainly kaolin, calcium carbonate and talc), binders (such as starch, cellulose and polyvinyl alcohol) and latex-based processing aids, which is spread on the paper to make it as smooth and uniform as possible. This facilitates printing and improves the rendering of text and images because the surface is smooth, and the light reflects evenly. In addition, the paper undergoes a subsequent calendering treatment to raise the gloss level: the more it is calendered, the glossier it will be. This is where the entire difference between gloss and matte coating lies.But be careful -  there is a big difference between the two, not just aesthetically. It’s no coincidence that matte paper came into being to improve readability: extra-glossy surfaces may not only be annoying but also make it challenging to achieve a print gloss that exceeds the paper’s while maintaining high optical contrast on blacks and colour saturation. In other words, unless you varnish the images in register, the difference between the gloss of a very glossy paper in its printed parts and the paper can often be much lower compared to a matte paper.  There is, however, the correct middle ground, namely the semi-mattes, or satins, which have less wrinkled surfaces than opaque and do not have a translucent effect. They are also a good compromise for printing and subsequent processing because they are more resistant to the abrasion that often affects mattes, which it is generally almost always better to varnish. There are dozens of gloss and matte coated papers in the offerings of paper mills because they are the most widespread for most printed objects with a range covering all weights and uses. With papers that are now highly tried and tested, and some of which have existed for decades, such as Magno by Sappi and R4 by Burgo Group to name but two, it is always good practice to have updated cards and samples. Beyond the aesthetic choices, it is always a good idea to think about the intended use: for example, would you use a gloss coating for a notepad? Better not to, since the reduction of porosity and the use of resins and latex hinders the transfer of ink or pencil lead. And yet, there is no shortage of schoolbooks printed on this paper.

Special or glazed coatings
Taking the coating to the extreme results in super-coated coatings with a very smooth enamel effect. The coating in these papers has a high binding agent content that almost lacquers the surface to a mirror finish. To achieve this extreme effect, the coating is applied off-line and can be used on one side only. They can be white with excellent colour rendering and coloured, in pulp or only on the surface. A good example is the Bindakote series by Favini that is available in mono and bi-patinated white, coloured (including black), pearly and satin. But the use of pigments opens up to the most varied finishes  - mica, metallic (like Fedrigoni’s Splendorlux Metal), gold and silver (like Gruppo Cordenons’ Venicelux series), iridescent and pearly like Fedrigoni’s Sirio Pearl. These papers all have good rigidity, high creasing resistance, excellent die-cutting and folding-pasting performance. They are particularly suitable for greeting cards, invitations, catalogues, brochures, luxury editions, luxury packaging, menus, and business cards.

Natural uncoated
This name generally refers to natural paper that has not been coated. Usually, they can be classified either by fibre, “with wood” and “without wood” (i.e. with pure cellulose), or by surface finish, “smooth” and “rough”. They range from uncoated paper for publishing - what we usually identify as the classic paper for printing prestige works with a lot of text (in other words, editorial publications, books and manuals, and paperbacks) to the much less prestigious newsprint, in the improved newsprint variants, coated or calendered-white for offset or rotogravure. These papers are very porous and consequently are also very absorbent so that, if they are not treated with resins that reduce ink penetration, they have a yield that tends to reduce the colours in the case of solid backgrounds or excessive use of black.  What makes the difference in natural papers is, above all, the presence of wood (or rather, lignin) which tends to turn yellow with time, and not the calendering, which only contributes to making them smoother. It is especially noticeable in books that through exposure to light and oxidisation, turn yellow at the edges over time while the centre of the page preserves the original colour, and in high circulation magazines printed in rotogravure that use a smooth but low-quality paper. There are also high-quality papers that are not affected by this problem, such as Fedrigoni’s Splendorgel Extra White made of pure cellulose or the so-called Bible paper. This type of paper is extremely thin, with weights between 25 and 40 g/m², is completely wood-free and contains cotton or linen to increase resistance. It is used to make Bibles, encyclopaedias, dictionaries or books that have a large number of pages. An example is Koehler’s PakoPharm, which has a gloss of 100. There are even natural coloured papers in pulp, like the Pergraphica from the Mondi paper mill, which is also available in an Infinite Black version.

Creative paper
But the beauty of paper comes in its creative, high-performance and very communicative versions. Here you are spoilt for choice with types, colourings and finishes. These are still industrial products, but they maintain the feeling of craftsmanship that standard or consumer papers do not have. Traditionally, they are divided into marked, laid and embossed. In general, they are all characterised by a surface that is not smooth but marked by a texture, and they have a rough and textured appearance. The markings have bas-relief motifs imprinted with felt during the sheet formation phase in the paper mill. As the grammage increases, the marking also becomes very sharp. This is the case with Modigliani Bianca/Neve (Gruppo Cordenons) or Tintoretto Gesso (Fedrigoni), a natural paper made of pure cellulose, “crisp” to the touch, marked with felt on both sides: the surface pattern is light and uniform and seems like “orange peel”. It lends itself to the creation of bookshop editions, brochures, pamphlets, and coordinated graphic materials but also menus, invitations and greeting cards. The laid papers can be recognised thanks to a regular, more or less thick weave, made up of vertical stripes, called wire marks, or horizontal multi-stripes, called ‘catenelle’ (chains). The effect achieved is a chiaroscuro that has only an aesthetic function. They are particularly suitable for luxury editions, monographs, brochures, inserts and catalogues, and are used in paper-making and bookbinding.  There are also laid papers in adhesive versions for food use, such as wine labels. Examples are the Label Stucco Corolla by Fedrigoni in white and ivory versions and the Constellation Snow by Arconvert. Care should be taken not to confuse kraft paper, which appears to be laid, with ‘artistic’ laid papers. We’ll look at it later, but packaging paper has remarkable physical qualities that go beyond its raw appearance.  Embossed papers are blind embossed through the goffering process by which an embossed design is reproduced on paper, such as the texture of leather, the grain of wood, a mark, geometric or creative figures, through a cliché with the help of pressure and possibly heat. This is done through two rollers, one of steel and the other covered with paper or cotton, which imprint a more regular pattern than the marked ones, but with a much greater variety than the laid paper that only has vertical or horizontal patterns. This paper, also known as embossed, can be produced on commission to obtain textured, striped, hammered, geometric effects inspired by natural textures: finishes that are chosen above all for packaging because they can convey unique, three-dimensional tactile sensations that add more value to the print. Remember, however, that altering the flatness of the paper also means changing the way it reflects light and consequently, the colour or degree of gloss.

Watermarked paper
This type of paper came into being at the very birth of the paper mills, probably at the end of the 13th century in Fabriano to distinguish their production with marks made directly on the paper but only visible when backlit. The anti-counterfeiting function of the watermark is still in use in banknotes, tax stamps, diplomas and certificates and in all those printed documents where the guarantee of authenticity is necessary, but it can also have an artistic value. Unlike paper marked with felt or embossed by roller, in watermarks, the design is in the mixture itself and not imprinted afterwards. The watermark is obtained during the formation of the paper when the pulp is still very wet. The pulp is “marked” by the reliefs on the formation plane by a negative pattern of the finished watermark. The fibres of the paper are naturally arranged following the reliefs and inlets, creating deposits that are almost imperceptible to the touch, but when backlit, they give life to drawings and inscriptions. Depending on how it is imprinted on the paper, the watermark is separately identified in Mould-made, Electrotype or Fourdrinier: what changes is the intensity and variety of the design’s tonal contrasts. Watermarked, however, does not mean parchment. That marbling, or clouding as they say in jargon, of certain parchment effect papers used for art prints, parchments, invitations, such as the Marina series by Fedrigoni or the Laguna by Favini, and which can be seen when backlit, is provided by the composition of the paste and not by the use of watermarks. Apart from the use of security papers which Fabriano Security is the leader in, the paper mills offer watermarked papers mainly for stationery and correspondence, but also for offset printing. An example is the Century Cotton series by Fedrigoni. But it’s worth exploring the many offerings from smaller paper mills that produce watermarked paper in a handcrafted manner to create genuinely exclusive prints. Beware only of the ‘runnability’ of these niche products since they don’t have the same guarantees as industrial papers.

Recycled paper
Recycled paper is produced from the waste of printers and the leftovers from the paper mills’ cuts, using up to 50 -100% of the recovered fibres. The reuse takes place after a particular chemical process removes the inks from the fibres. It should not be confused with recyclable paper, i.e. paper that can be reclaimed up to six times after its first use thus preserving natural resources. Recycled paper can be coated or uncoated and can have a natural look, tending towards grey, or it can have a high degree of whiteness. Let’s debunk the myth of the poor quality of this type of paper: recycled paper has a condition similar to virgin cellulose paper, as well as a lower environmental impact. It is used for art books, institutional financial reports, catalogues, postcards, brochures and invitations. Yet not all papers are suitable for making recycled paper. According to Comieco, if the paper or cardboard has been soiled, it cannot be sorted - so no tissues or greasy kitchen towels. Obviously, paper with synthetic parts or non-cellulose materials, such as paper laminated with aluminium or plastic, receipts and POS receipts cannot be recycled. This is one of the most obvious mistakes: they are made of thermal paper where the ink is directly in the fibre and is activated by heat. Processing waste paper results in a fibre loss of about 20-25% each time, so the same waste paper can be reused about 4 or 5 times. Given this situation, it is evident that it will never be possible to eliminate the use of virgin cellulose; otherwise, the quality of all the paper produced will be degraded too much. Today one of the largest paper mills specialising in the production of recycled paper for offset and digital printing is Steinbeis Papier in Germany with an annual output of about 300,000 tons of paper. These are light-coated papers from the Charisma and Select line. The former is intended for reel printing characterised by low grammage for the printing of magazines, catalogues and advertising material; the latter, with grammages up to 130 g/m² and excellent resistance to creasing and finishing, is intended for covers.
But there are also more sought-after recycled papers such as Fedrigoni’s Woodstock: made up of 80% recycled fibres that can be glimpsed on the surface and 20% pure cellulose, it is a recycled paper with a smoothed surface finish and, in the non-coloured version, a delicate birch white colour that conveys a feeling of essential naturalness.

Eco-friendly paper
Recycled also brings to mind eco-friendly, but the two things are not synonymous. The definition of eco-friendly paper refers to recycled paper with 100% recycled fibres and not subject to de-inking or bleaching operations. So recycled paper is not necessarily also eco-friendly: it is the use of waste paper, as well as the absence of processing and pollutants that make this substrate an eco-friendly product in all its aspects. Recycled paper, on the other hand, is different, and processes that have an environmental impact are used to obtain it. However, paper mills are working to reduce or eliminate this impact. ICMA just recently announced its new 100% R Bases paper, 100% recycled, FSC Recycled Credit certified, produced without the intermediate step of the production of recycled pulp - with the resulting energy and resource savings - and made without the use of optical brighteners. In general, eco-friendly means a paper that reflects specific production standards that respect the environment. In this sense, FSC remains the most accredited forest certification in the world, guaranteeing proper forest management and traceability of the derived products and the entire supply chain. At present there is practically no paper that does not have FSC certification in one of its forms: “100%” when the material comes entirely from certified forests; “recycled” when the wood or paper in the product comes from recycled and recovered material; “mixed” indicating that the wood or paper in the product comes from FSC certified material, recycled material or verified wood (not less than 70%).

Pulp-tinted paper
You just need to browse through any catalogue of papers to see that paper is not only white but can be coloured even before it is printed. Pulp tinting is the common denominator of almost all the types seen so far and to obtain them paper mills add dyes directly into the tint mixing. They are different kinds of dyes, derived from natural or synthetic pigments. In particular, some paper mills use waste by-products from agro-industrial processing which, compared to pigments, give a softer and more natural colouring. But when should you choose a pulp tint rather than printing a white paper? Contrary to what you might think, one discriminating factor is not the need to have a precise tint; this is because paper mills are now able to create coloured papers for the sample. A pulp tint has the advantage of allowing the same processing as white paper without looking “split” not only in the fold and crease points - a problem that most of all affects the more fibrous papers or counter-fibre points - but also in cutting and die-cutting. Unless special finishes or coatings are applied on the surfaces, even with ennoblements such as varnishing and plasticising, they behave very well but be careful just with hot printing: metal ribbons react with certain substances such as carbon black, which is why some paper mills use pigments without Carbon Black in their pulp dyeing to overcome this problem. One example is Fedrigoni Sirio Colour Rough, which is FSC certified, made of pure E.C.F. cellulose, biodegradable and recyclable.  Pulp-tinted cardboards, which exploit thickness for different colour effects, are also interesting. Borsotti produces cardboards for coupling with black or beige core with thicknesses up to 4 mm.

Special paper
If we look around at paper with unique features, if not with superpowers, there is more than meets the eye. Because paper is an extraordinary material: a few essential elements mixed in different ways, the addition of chemicals or special treatments and you get papers with different physical characteristics, which are sometimes surprising. There are greaseproof and stain-resistant papers, such as Arconvert’s Immaculate, which are impenetrable to vegetable oils and fats and therefore perfect for olive oil packaging and for all those products that require resistance to oily substances. Before this, the alternative was to use naturally dark-coloured papers to try to mask the stain or self-adhesive films that did not reflect the natural characteristics of the product. There are anti-mashing papers, i.e. resistant to humidity and water, not only for large formats such as Blue Back opaque, studied and tested to resist outdoor weathering, but also for labels. These are 100% natural papers made of cotton fibre with anti-mildew and anti-mashing treatment, with hammered and laid finishings, which are less porous and suitable for prestigious work such as wine and liqueur labels and are in general able to withstand the ice-bucket test.  Vegetable parchment is anti-moisture and resistant to fats and cooking. It is suitable for direct contact with fatty foods such as butter, fresh cheese, cold cuts, meat, fish, baked goods. Similar, but not the same, is baking paper, which can withstand temperatures of up to 250 degrees, even though it can break down at over 220 degrees. It can be a paper simply coated with silicone, or paper similar to parchment obtained in a bath based on chemical agents such as sulphuric acid. Another high-performance paper, the so-called Kraft paper, is a type of packaging paper technically better than ordinary wrapping paper. In German Kraft means strength, and this paper makes resistance its main strength. Produced according to the kraft process, invented by Carl F. Dahl in 1879, it is made of softwood pulp treated with moderately refined sulphate to maximise tensile strength and burst strength without compromising tear resistance. It is a type of paper produced with weights ranging from 65 to 100 g/m2 that is widely used in the manufacture of multi-sheet bags for cement, lime, fertilisers, flour, chemical products, synthetic resins, as well as various container bags and pouches.

Extreme paper
Not to mention paper suitable for coupling with plastic or metal films, there is also a type of paper that we can define as extreme because it can resist its two traditional enemies: tearing and fire. Tear-resistant paper isn’t really paper – it’s synthetic. For example, Polyart has a plastic base of high-density polyethene, which is resistant to tears, water, oil and many chemicals. For this reason, it is suitable for cards, menus, maps and products subjected to continuous manipulation, but above all, it is printed, folded and cut like any other coated paper without limits of ‘runnability’. But there are also others based on Tyvek, a non-woven fabric patented by DuPont, the company that makes holiday club bracelets or disposable clothing. With a paper-like appearance, it is not only resistant to acids and bases but also breathable yet impermeable to water, non-toxic and recyclable. It prints, does not tear but it can be cut.
On the other hand, Burgo Group’s Solaris Flam has been developed to resist fire, designed for printing indoor posters and for coupling on cardboard for displays where the printing substrate must meet quality requirements and comply with strict safety standards such as in shopping centres, subways, railway stations, galleries, cinemas, theatres, and museums. Treated with flame retardant agents based on inorganic compounds of phosphorus and nitrogen, it is classified as M1 (non-flammable fuel) as a reaction to fire. It is wood-free with good opacity and whiteness and with excellent performance in both offset and digital printing. Finally, there are also anti-bacterial papers such as Protections made up of 100% pure pulp, whose fibres are treated with stabilised silver ions with natural anti-bacterial properties that are stable over time. In 2012, the Italian Institute of Technology patented a system to make cellulose materials such as paper or cotton fabrics, waterproof, magnetic, anti-bacterial or fluorescent through nano-particles, without compromising their primitive characteristics, thus remaining printable and workable precisely as before. In short, paper is part of our life: there would still be a lot to discover, but it would take reams and reams... of paper, of course.
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The words of the paper

Grammage
Grammage is the specific weight of paper expressed in grammes per square metre (g/m²). Its value depends on the thickness and the consistency of the sheet of paper; the latter is linked to the type of processing, the amount of wood fibre present (the thicker the wood fibre, the thicker it is), the composition of the paper itself and the treatments undergone. Usually, as the weight increases, so does the thickness of the paper and its stiffness. However, this is not a strict rule, as there are thin but extraordinarily consistent and rigid types of paper. There are different grammage classifications, but the simplest is as follows:
Plain paper or Bible paper weighs between 25 and 35 grammes per square metre.
Lightweight paper: between 60 and 90 grammes (for example, for photocopies)
Printing paper: between 90 and 140 grammes (letterhead)
Lightboard: between 140 and 360 grammes (business cards, presentations)
Cardboard: all paper materials exceeding 360 grammes

Degree of whiteness
The degree of whiteness indicates the degree of brightness of the paper compared to the set standard (magnesium oxide = 100%). The higher the degree of whiteness, the whiter the paper. In this case as well, the degree of whiteness of the paper depends on the fibre strength and the chemical processes carried out during processing. 

Degree of gloss
It represents the way paper reflects light. Greater brilliance has the effect of greater reflection and therefore, a higher degree of gloss. Given the maximum gloss factor fixed at 100 (light reflected from a black glass), a glossy paper ranges from 50 to 80, a satin paper (silk) from 20 to 40 and matte from 10 to 20.

Porosity (PPS)
The geometric shape of the paper surface is defined as the deviation from the ideal perfectly flat surface. The smaller and more evenly distributed the irregularities on the surface, the smoother the paper is. The higher the PPS value, the more porous the paper is.

Opacity
Indicates the degree of impermeability to light, expressed as a percentage of the reflected light. A high value indicates an opaque paper, while below a particular value, we speak of transparent paper. The weight is undoubtedly decisive in increasing opacity as well as the thickness and colour of the paper.

Bulk index
The bulk index is measured using a micrometre, and it is the ratio between the thickness and the weight of a sheet of paper.

Paper grain
Paper is made up of a series of fibres generally arranged in the paper-making direction. Depending on the type of paper and the raw material used (pulp, wood pulp, recycled paper, rags, etc.), the structure can be more or less macroscopic. Humidity is the critical factor to which paper fibres are most sensitive: the higher the humidity, the more the fibres tend to swell in width, up to 20%. In this sense, paper can be considered a living material.

Format
It indicates the surface of the substrate, the so-called sheet. According to ISO 216, the initial format is a sheet of one square metre measuring 84.1×118.9 cm. Subsequent measurements are obtained by ideally cutting the square metre along its largest side in half. The following formats are A1, A2, A3, A4, A5 etc. The most common format is A4. There is also the B series, used for posters and large prints, and the C series, mainly used for envelopes. And yet, you will hardly ever hear an offset printer talking about ISO formats: because once the sheet has been printed, most of the time it is folded and then trimmed to the required finished format. And to do this, the printer must leave a margin to work with for the packer, thinking about formats called “immaculate”. This is why the most common paper sizes used by printers are 70x100 cm and 64x88 cm with their 50x70, 35x50 and 44x64 cm sub-multiples. This is for sheet-fed printers, at least: for reels, the height is used.