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Knowledgebase

CMYK

The CMYK colour model is the standard colour model used in offset printing. It is a subtractive colour model; a subtractive colour model means that a limited number of colours are used together to make up a wider range of colours; each made by partially or completely subtracting each of the colours. CMYK is a colour model that uses four different coloured inks: cyan, magenta, yellow and key (black).

The printing process works by each colour of ink printing the required amount onto a single point. The combination of the colours makes up the final colour that is visible. CMYK is used in all professional printing which can be unfavourable for graphic designers as computers use the RGB colour model making it hard to match colours on screen and in print. If colour matching is required for the product, it is important that swatches are used when designing the product for print. Swatches are a printed colour sample that can be used to select the correct colours based on the printer being used.

Watermark

A watermark is an image or pattern that is put into paper. It appears as various different shades of light and dark when viewed in light which are caused by thickness and density variations throughout the watermark.

A watermark can be created using one of two processes: the dandy roll process and the cylinder mould process with the latter being much more complex.

The dandy roll process works by impressing a water-coated metal stamp, or dandy roll, in the shape of the desired watermark during the paper manufacturing process. The dandy roll is a light roller with a mesh covering that is embossed with the watermark design. The embossing is transferred to the pulp fibres, compressing the areas where the design is rolled and causing a change in density.

The cylinder mould process is more complex but also offers better results and a more detailed image. This process uses tonal depth to create a grayscale image. The image is then transferred directly onto a roller as a 3-dimensional image with darker areas compressing the paper more when rolled. This type of process is preferred over the dandy roll process when used for official government documents due to its superior clarity and detail.

Foil Stamping

Foil stamping is a process used in commercial printing to apply a pigment or metallic foil to stationery. Foil stamping machines work similarly to engraving machines by using either pressure or heat to transfer the foil to a wide range of solid surfaces. Once the design has been finalized, a metal die is created in the applicable shape and embossing is also added if a 3D effect is required.

Foil stamping has a variety of applications including pencils, photographs, and books, but can be used on a variety of solid surfaces and is often used on paper to promote authenticity. Foil stamping is often used in conjunction with embossing to offer a striking 3D image.

Embossed Paper

Embossed paper is a type of paper that incorporates a raised or recessed image into the design.

The process requires the fabrication of two dies; one with a recessed image and the other with a recessed image so that they fit together and the paper can be placed between the two to create the desired embossed image. The thickness of the die is very important as it affects the final image and depending on the individual design will need to be modified to ensure the embossed design shows as much detail as possible. Both pressure and heat are applied to the product to create the final image. The process is often quite costly as it requires a separate run after the source material has been treated by varnishing or lamination.

Continuous Stationery

Continuous stationery is a format of paper that is, as is made obvious by its name, continuous. This means that it is well suited for applications that require finishing techniques such as folding and perforation applying.

Acid-free paper

Acid-free paper is a type of paper that if placed in water, will yield a neutral pH (approx. pH7). Acid-free paper can be made from a range of cellulose fibres providing the active acid component is removed during the processing procedure. As well as having the active acid components removed, acid-free paper is also lignin and sulphur free. Paper that still contains lignin tends to go yellow and brittle, deteriorating further over time. When exposed to light, acid based paper also breaks down more quickly. Most paper nowadays is acid-free as the filtering material used in paper production has changed from clay to chalk.

Cartridge Paper

Cartridge paper is a paper that has a high opacity and weight. It has a variety of uses including but not limited to envelopes and letters as well as pencil and ink drawings. It’s attraction from artists is the paper’s ability to absorb paints better than most other paper types. This makes it an attractive option for a range of uses.

Archival Paper

Archival paper is a type of acid-free paper that has being made to be especially permanent and durable. It is most suited to publications and documents with high legal or historical importance. Some documents use cotton rag paper for archival purposes and as a result, archival paper can often be separated into two separate categories; conservation-grade paper is an acid-free paper made from wood-based pulp and archival-grade paper (also known as Museum grade paper) is a cotton rag paper made from cotton pulp.

Bond Paper

Bond paper is a very high quality and durable writing paper which has a weight of above 50gsm. The paper composition usually comprises wholly, or in part, of rag pulp (also known as cotton pulp) which increases its durability and resistance to tearing and breaking. The name originates from the paper originally being used for documents such as government bonds but nowadays it is most commonly used in business correspondence as letterheads and similar stationery.

Art Paper

Art paper is a type of high quality coated paper that is usually coated with casein glue and china clay. It is then glazed under high pressure rollers to give it a smooth surface. The paper is designed to handle a variety of depths of both paint, pencil and ink and is therefore considered a premium product.

Manila paper

Manila paper is a light brown paper that is relatively inexpensive as it is often made from less refined and treated papers than other products. It is generally made using semi-bleached wood fibres. The paper is one of the more inexpensive types of paper and is most commonly used for envelopes as well as in the fashion world to make clothing patterns.

Airmail Paper

Airmail paper is a type of paper typically with a weight of 40gsm or lower. The lightweight paper is used to decrease overall weight and therefore decrease the cost of posting letters via airmail. Airmail paper can be used for both the envelope and the content of the envelope. Although the paper used is lightweight, it is also a strong, high quality paper and is created to withstand damage when posting via airmail.

Recycled paper

Recycled paper is a paper that uses waste paper to create new paper products. Waste paper is split into three main categories: mill broke, pre-consumer waste, and post-consumer waste. Mill broke and pre-consumer waste is a by-product of the production process including offcuts and rejected material. Post-consumer waste paper is a product that has already been created into a final product then been discarded by the individual consumer.

Offset Paper

Offset is a type of wood-free uncoated paper that has been processed into a pulp to remove lignin from the fibres. The paper consists of a mixture of softwood and hardwood pulps. Wood-free uncoated papers are of high quality and offer a more natural look and feel compared to other types of paper. This kind of paper benefits from properties such as high strength and brightness. Offset paper differs from other papers as it has to have an ISO brightness greater than 80% as well as a weight in the range of 40-300gsm.

Offset Printing

Offset printing, otherwise known as offset lithography, is one of the most common methods of commercial and professional printing due to its scalability and cost-effectiveness as well as the lack of maintenance required resulting in maximum productivity.

In a nutshell, the machine works by using a plate that contains the design or text designated for the paper which makes an inked impression of the design on a rubber-blanketed cylinder. From the rubber-blanketed cylinder it is then transferred onto the paper. For colour printing, a cylinder is used for each colour: Cyan, Magenta, Yellow and Black. The paper runs under each cylinder in turn adding the detail required for each colour.

Offset printing is best suited for large quantity printing jobs such as newspapers and magazines due to the complexity of setting up the plates and printing press. As well as taking time to set up, another slight disadvantage in comparison to other print processes is the quality of the image. This method does have its advantages as it is very cheap in comparison to printing high quantities using other methods and provides very consistent image production. Although still high quality, the quality is not quite as good as rotogravure or photogravure printing methods meaning this is mainly suitable for disposable products such as magazines, newspapers, brochures, and stationery.

Gloss finish

A gloss finish is a type of finish applied to a paper that gives a shiny overall finish. Glossy paper generally improves sharpness and vibrancy of image, although it easily picks up finger prints which can be easily visible meaning it should be handled with care. As well as these properties, various grades of gloss paper are available that can provide longer lasting colours.

Matt finish

A matt finish provides a high quality print without the shiny finish that glossy paper provides meaning the image appears less vibrant. Although this is the case, matt finishes allow for a more robust finish as they are less affected by finger prints and dirt. Matt paper is also available in a variety of grades and qualities offering slightly differing properties. One of the main reasons for using a matt finish is to reduce glare on the image in comparison to a gloss finish.

Satin finish

A satin finish offers a middle ground between matt and gloss offering a slight sheen leading to a better looking print as opposed to matte. Satin finish is generally comparable to a semi-gloss finish and is a good compromise if looking for a vibrant, sharp image whilst trying to decrease the likelihood of accruing fingerprints.

International Standard Paper Sizes

To ensure conformity amongst paper production, an International Standard was made to ensure papers were the same size throughout the world. With the exception of the US and Canada, ISO standards use A, B and C series’ of paper. A series is the most common and A4 paper is most commonly used for letters and printing by consumers. The A series goes from A0 to A10 with each number being half the size of the previous. A0 is defined to have an area of exactly 1 square meter with sides of ratio 1:√2. As well as the three main standard sizes, a number of variations also exist for printing including SRA to allow for bled work as well as RA to allow for a trim.

ICC Profile

An ICC profile is a set of data according to standards set out by the ICC (International Color Consortium) that defines a colour input or output device. ICC Profiles are used to determine the attributes of a particular device to ensure colour accuracy and concurrency across devices and platforms. A number of international standards use ICC profiles such as digital file formats and printing methods. The profiles are used to convert colour data between regular colour spaces such as RGB and CMYK to device-specific profiles ensuring accuracy when converting between formats as well as between digital and print formats.

Photoshop

Adobe Photoshop, now in its 14th version, is a graphics editing program developed by Adobe Systems. Photoshop is currently one of the most common software packages used to create graphics and images due to its versatility and wide array of tools and is available in its current form as a subscription service as well as previous versions being available with a perpetual software license. Due to the software’s popularity, the format is supported in a range of its competitors’ products. Photoshop uses the file extension ‘.PSD’ which is a format commonly sent to be used for printing due to its lossless format and ability to retain significant detail about the created image.

Biodegradable

Biodegradability is a property that allows a material the capability of decaying through the action of living organisms. This is very important when looking for an environmentally friendly product. Sustainable disposal of products means waste is reduced and products are recycled into the ecosystem.

ECF (Elemental Chlorine Free)

Elemental Chlorine Free paper is a technique used in the production of paper to bleach wood pulp using chlorine dioxide as opposed to using a chlorine gas. This method of production is more environmentally sound than the original method as it drastically reduces the production of carcinogens; dioxins and other harmful compounds.

TCF (Totally Chlorine Free)

As the name suggests, Totally Chlorine Free production is a method that does not use any chlorine-based compounds in the bleaching process. This makes the process extremely environmentally friendly as it eliminates the production of chlorinated carcinogenic compounds such as dioxins as well as reducing water usage throughout the bleaching process.

Lignin

Lignin is a complex compound derived from wood. It provides structure to the cells. Pulp that still contains lignin provides a much stronger overall product but also has its downfalls. Lignin breaks down over time causing paper to go brown meaning it is not good for products requiring a long shelf-life. Many paper products generally reduce the lignin content to a minimal amount although some products such as newspapers still contain lignin as removing it can make the overall product more costly.

Chromophore

Chromophores are the part of molecules responsible for its colour. By modifying the chromophore content in paper during the bleaching process, you can modify the brightness to a certain extent.

Pulping Process

To turn wood into the pulp required to make paper, it must undergo a multi-staged process. Wood pulp used to make paper comes from softwood trees such as pine and fir, as well as hardwoods such as aspen and birch. Pulp can be manufactured from these products using mechanical, semi-mechanical or chemical methods. As well as the pulping process, bleaching can also occur during the process depending on product requirements. Chemical pulping involves degrading lignin and hemicellulose in the paper to allow it to be removed from the cellulose fibres. Mechanical pulping can be achieved through a number of methods and works by physically tearing the cellulose fibres from one another. A number of hybrid, or semi-mechanical, processes exist that use a combination of mechanical and chemical processes to produce stronger fibres leading to a stronger end product.

Bleaching

When paper is produced, it generally goes through a bleaching process to increase brightness, change colour, as well as ensuring uniformity throughout the paper. There is a range of bleaching processes available that use a range of different chemicals to produce different results as well as perform different functions. There are two main approaches used in the chemical bleaching of paper. The first method uses a selection of chemicals that destroy part of the chromophoric group leading to brighter paper but do not modify the lignin content of the pulp. This can produce a product with up to 70% brightness as well as providing a high yield. The other method used involves removing almost all the lignin in the pulp. This method can provide upwards of 90% brightness but provides a much lower pulp yield making it less efficient but giving better quality results.

Tree-free paper

Tree-free paper, as its name suggests, is a paper produced without the use of wood pulp from trees. It is generally considered to be more eco-friendly than paper production using trees as it makes better use of waste products such as agricultural residues, textile and cordage wastes, and wild plants. Although the product is very environmentally friendly, technology to produce the product on a large enough scale to make it viable is limited meaning the product is not a competitive alternative to paper made using trees.

Chemicals

Although there are around 3000 chemicals that can be used to create paper, realistically there are only around 200 that are used on a regular basis. Each of the 200 chemicals are selected to perform an individual task and satisfy a very specific need relevant to the paper production process all the way from separating the fibres from the raw material used through to pulping, bleaching, pressing and drying. There are number of chemicals that can be used for each part of the process producing varying results which can be adjusted depending upon the required final product.

Calender

The calender process comes at the end of the production and is used to smooth the paper and ensure uniformity across the final product. Calendering can also be used to apply a finish to the product such as a matt or gloss finish. The method of calendering depends on the rollers being used in the machine as well as the speed at which the paper is passed through the machine. The rollers use adjustable heat, pressure and speed to apply gloss by compressing the paper as is passes between them.

Grain

The grain of the paper product is the way in which the majority of the fibres lie within the paper. As the pulp moves through the papermaking machines, the fibres tend to align themselves in the direction of movement. By knowing the grain, it makes binding much easier as the fold can run parallel making a smoother fold and a more aesthetically pleasing product. Grain direction is also important in packaging papers as it can dramatically affect the finished result in terms of visible and practical effects. In label papers, the grain direction usually runs “east-west” horizontally around a package or bottle. In general, the grain runs in the direction of the longer side of the sheet.