Sunday, 17 November 2013

FURTHER RESEARCH: PRINT PROCESS

Whilst designing the print process booklet, and reading over my notes for the content, I found other print processes and further information needed for completion of the booklet. These are shown below.

Mono-Printing:

Mono printing uses printing materials but only produces one image.


Technique one

  1. place glass on top of an image
  2. trace the image onto the glass using paint
  3. lay paper over the surface and smooth the back with a roller
  4. peel off the paper to reveal your image
Explore the different thicknesses of ink and try scratching into the ink.

Technique two

  1. roll out a layer of thin ink onto a surface and then place paper over the top
  2. draw onto the back of the paper
  3. peel off the paper
Try different tools to create different thicknesses of line, or use your fingers to create shading techniques.

Screen Printing, Screen Prep:
One way to ensure that you can make high quality stencils easily is to prepare the mesh for emulsion coating properly. Mesh preparation or “mesh prep” is a crucial phase in the screen making process that may often be over looked. Proper preparation of the mesh is an inexpensive way to improve stencil adhesion, prevent fisheyes, pinholes, and premature stencil breakdown.

When screen printing mesh manufacturers finish making the mesh it is cleaned. But the mesh has a long way to go from the factory to your print shop. It is during the transportation and subsequent handling at different points during transport that will contaminate the mesh. Even receiving, handling and screen stretching in your own print shop will leave greasy residues, dust, and dirt on the mesh. In order to create an ideal situation for the emulsion to adhere to the mesh and do its job properly, we must prepare the mesh correctly.

There are 2 parts to proper mesh preparation. First the mesh must be thoroughly cleaned and degreased for reasons stated above. Second the mesh should be abraded. Abrasion of the mesh is not always recommended for direct liquid emulsions but is suggested for capillary films. But abrading the mesh will improve emulsion adhesion in either application and it is a good idea to abrade your mesh some only when it is brand new. Be careful not to over abrade the mesh and cause premature mesh wear.

Degreasing should be performed every time you coat a screen with emulsion. There are many degreasing and abrading combination chemicals which will do both steps at the same time. Other products are made to work individually. Ulano’s Microgrit is a fine powder that is used independently of a degreaser. If you are a home based printer and choose to use a household scrubbing detergent like Comet® or SoftScrub® be aware that these cleaning agents have grit that is too coarse for this purpose. Using these products can damage the mesh which can increase staining and hazing problems with the mesh as well as weaken its integrity. Also note that if you use a dish detergent for degreasing, most brands contain lanolin or wool grease, which keeps skin from drying out. Those additives may make the degreasing counterproductive.

Degreasers can be purchased with or without wetting agents. A degreaser with a wetting agent will leave a smooth, even, sheet of water on the mesh when rinsed. This type of degreaser with wetting agent is recommended for use with capillary films although many stencil technicians in the industry claim that they also improve the coating ability for direct liquid emulsions. Degreasers without wetting agents are designed for use with direct liquid emulsions. Some popular degreasers without wetting agents include Ulano #3 Degreaser and Chemical Consultants, (ICC), Nutralyze. There are manufacturers who make wetting agents separate from the degreaser, such as Ulano #25 All Mesh Prep and Chromaline, Chroma/Wet Wetting Agent.

It is best to use a degreaser and a mesh abrader separately so that you can only abrade the mesh when you need to. Degreasing is recommended every time you coat your screens but abrading is not. For best results, purchase degreasers and mesh abraders that are specifically manufactured for screen printing applications. Make sure to follow the manufacturer’s instructions for chemical usage and disposal.

Flexography:

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).

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. In recent years there has also been a move towards laminates, where two or more materials are bonded together to produce new material with different properties than either of the originals. 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 achievable now with modern technology high-end printers. Flexo printing is widely used in theconverting 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.
Etching:
Etching is the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio in the metal (the original process—in modern manufacturing other chemicals may be used on other types of material). As an intaglio method of printmaking, it is, along with engraving, the most important technique for old master prints, and remains in wide use today.




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