Spot Colour: Print technicians and Graphic Designers around the world use the term spot colour to mean any colour generated by a non-standard offset ink; such as metallic, fluorescent, spot varnish, or custom hand-mixed inks. (as opposed to obtaining a colour by via mix of cmyk)
Greyscale: One colour black and all the shades of grey through to white (black and white photography is grey scale)
Monochrome (mono): Monochromatic colours are all the colours of a single hue derived from one colour and extended using the shades,tones and tints of that colour.
PALETTE
Halftone: This is a mechanical process (as opposed to chemical) for converting tonal values into a series of dots that although solid dots, when printed give the impression of continuous tone.
Trio Chromatic Inks: The ink is not dense, meaning that it overlaps other inks that are printed on the page. Here you can see an example of the overlaying. Almost like lower transparency layers on photoshop.
Duotone: Duotone is a halftone
reproduction of an image using the superimposition of one contrasting
colour halftone (traditionally black) over another color halftone. This
is most often used to bring out middle tones and highlights of an image.
The most common colors used are blue, yellow, browns and reds.
Rubylith: A brand of masking film, invented and trademarked by the Ulano Corporation. Today the brand has become genericized to the point that it has become synonymous with all coloured masking films.
Rubylith consists of two films sandwiched together. The bottom layer is a clear polyester backing sheet. The top layer is a translucent, red coloured, self adhesive emulsion. It is designed to be both easy to cut with a knife and light safe for use with orthochromatic films.
Rubylith is used in many areas of graphic design, typically to produce masks for various printing techniques. For example it is often used to mask off areas of a design when using a photoresist to produce printing plates for offset lithography or gravure. It is also frequently used during screen-printing.
Substrate: Substrate is a term used in converting process such as printing or coating as a more general term to describe the base material onto which e.g. images will be printed. Base materials include (though are not limited to):
- plastic films or foils,
- release liner
- textiles,
- fabrics,
- plastic containers
- any variety of paper (lightweight, heavyweight, coated, uncoated, paperboard, cardboard, etc.), or
- parchment.
Stock: Genrally stock can be divided down into 3 categories- Paper, Paperboard or Card Board - as well as 3 finishes - Matt, Satin, Glossy
Stock Weight: Refers to the the thickness or density of the chosen Paper or Board. Paper products that let little or no light pass through (e.g. poster board) are considered dense or heavy. Paper products that allow some light to pass through (e.g. tissue paper) are considered lightweight.
Print Processes
Flexography (often abbreviated to flexo) is a form of printing process which utilizes a flexible relief plate. It is essentially a modern version of letterpress which can be used for printing on almost any type of substrate, including plastic, metallic films, cellophane, and paper. It is widely used for printing on the non-porous substrates required for various types of food packaging (it is also well suited for printing large areas of solid color).
Common Applications
Flexo has an advantage over lithography in that it can use a wider range of inks, water based rather than oil based inks, and is good at printing on a variety of different materials like plastic, foil, acetate film, brown paper, and other materials used in packaging. Typical products printed using flexography include brown corrugated boxes, flexible packaging including retail and shopping bags, food and hygiene bags and sacks, milk and beverage cartons, flexible plastics, self adhesive labels, disposable cups and containers, envelopes and wallpaper. A number of newspapers now eschew the more common offset lithography process in favour of flexo. Flexographic inks, like those used in gravure and unlike those used in lithography, generally have a low viscosity. This enables faster drying and, as a result, faster production, which results in lower costs.
Printing press speeds of up to 600 meters per minute (2000 feet per minute) are achieveable now with modern technology high-end printers. Flexo printing is widely used in the converting industry for printing plastic materials for packaging and other end uses. For maximum efficiency, the flexo presses produce large rolls of material that are then slit down to their finished size on slitting machines.
Refers to methods of printing from a digital based image directly to a variety of media. It usually refers to professional printing where small run jobs from desktop publishing and other digital sources are printed using large format and/or high volume laser or inkjet printers. Digital printing has a higher cost per page than more traditional offset printing methods but this price is usually offset by the cost saving in avoiding all the technical steps in between needed to make printing plates. It also allows for on demand printing, short turn around, and even a modification of the image (variable data) with each impression.The savings in labor and ever increasing capability of digital presses means digital printing is reaching a point where it could match or supersede offset printing technology's ability to produce larger print runs of several thousand sheets at a low price.
A technique that uses a woven mesh to support an ink-blocking stencil. The attached stencil forms open areas of mesh that transfer ink or other printable materials which can be pressed through the mesh as a sharp-edged image onto a substrate. A fill blade or squeegee is moved across the screen stencil, forcing or pumping ink into the mesh openings for transfer by capillary action during the squeegee stroke.
Screen printing is also a stencil method of print making in which a design is imposed on a screen of polyester or other fine mesh, with blank areas coated with an impermeable substance, and ink is forced into the mesh openings of the mesh by the fill blade or squeegee and onto the printing surface during the squeegee stroke. It is also known as silkscreen, serigraphy, and serigraph printing. A number of screens can be used to produce a multicoloured image.
A process that can transfer a 2-D image onto a 3-D object. This is accomplished using an indirect offset (gravure) printing process that involves an image being transferred from the cliché via a silicone pad onto a substrate. Pad printing is used for printing on otherwise impossible products in many industries including medical, automotive, promotional, apparel, and electronic objects, as well as appliances, sports equipment and toys. It can also be used to deposit functional materials such as conductive inks, adhesives, dyes and lubricants.
Physical changes within the ink film both on the cliché and on the pad allow it to leave the etched image area in favor of adhering to the pad, and to subsequently release from the pad in favor of adhering to the substrate.
The unique properties of the silicone pad enable it to pick the image up from a flat plane and transfer it to a variety of surfaces, such as flat, cylindrical, spherical, compound angles, textures, concave, or convex surfaces.
Common Applications
- Medical devices (surgical instruments, etc.)
- Implantable & in body medical items (catheter tubes, contact lenses, etc.)
- Golf ball logos/graphics
- Decorative designs/graphics appearing on Hot Wheels or Matchbox toy cars
- Automotive parts (turn signal indicators, panel controls, etc.)
- Letters on computer keyboards and calculator keys
- TV and computer monitors
- Identification labels and serial numbers for many applications
A printing technique in which the inked image is transferred (or "offset") from a plate to a rubber blanket, then to the printing surface. When used in combination with the lithographic process, which is based on the repulsion of oil and water, the offset technique employs a flat (planographic) image carrier on which the image to be printed obtains ink from ink rollers, while the non-printing area attracts a water-based film (called "fountain solution"), keeping the non-printing areas ink-free.
Development of the offset press came in two versions: in 1875 by Robert Barclay of England for printing on tin, and in 1903 by Ira Washington Rubel of the United States for printing on paper.
Common Applications:
- Newspapers
- Magazines
- Brochures
- Stationary
- Books
Advantages of offset printing compared to other printing methods include:
- Consistent high image quality. Offset printing produces sharp and clean images and type more easily than letterpress printing because the rubber blanket conforms to the texture of the printing surface.
- Quick and easy production of printing plates.
- Longer printing plate life than on direct litho presses because there is no direct contact between the plate and the printing surface. Properly developed plates running in conjunction with optimized inks and fountain solution may achieve run lengths of more than a million impressions.
- Cost. Offset printing is the cheapest method for producing high quality prints in commercial printing quantities.
- A further advantage of offset printing is the possibility of adjusting the amount of ink on the fountain roller with screw keys. Most commonly, a metal blade controls the amount of ink transferred from the ink trough to the fountain roller. By adjusting the screws, the gap between the blade and the fountain roller is altered, leading to the amount of ink applied to the roller to be increased or decreased in certain areas. Consequently the density of the colour in the respective area of the image is modified. On older machines the screws are adjusted manually, but on modern machines the screw keys are operated electronically by the printer controlling the machine, enabling a much more precise result.
- Slightly inferior image quality compared to rotogravure or photogravure printing.
- Propensity for anodized aluminum printing plates to become sensitive (due to chemical oxidation) and print in non-image/background areas when developed plates are not cared for properly.
- Time and cost associated with producing plates and printing press setup. As a result, very small quantity printing jobs are now moving to digital offset machines.
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