1. What is Offset Printing?
A. It is a process which uses an etched thin, flexible metal plate that fits to a curved cylinder. The inked image is transferred, or offset, from this plate to a revolving rubber covered cylinder, which in turn transfers the image to the paper/board.
2. What are the advantages of offset printing?
A. Consistent high image quality– sharper & cleaner.The advantages of offset printing include: · Consistent high image quality – sharper and cleaner than letterpress because the rubber blanket conforms to the texture of the printing surface.· Usability on a wide range of printing surfaces in addition to smooth paper (e.g.,non absorbent substrate)· Quick and easy production of printing plates.· Longer plate life than on direct litho presses – because there is no direct contact between the plate and the printing surface.During the 1950s, offset printing became the most popular form of commercial printing as improvements were made in plates, inks and paper, maximizing the technique’s superior production speed and plate durability. Today, the majority of printing, including newspapers, is done by the offset process.
3. What colors are used in offset printing?
A. Ink Colors.Commercial offset printing (also known as offset lithography) utilize four basic ink colors: CMYK. Dots of cyan (blue), magenta (red), yellow, and black (the K) are placed next to each other in specific patterns that trick the eye into seeing millions of colors. Additionally, offset printing can use premixed inks in a variety of specific colors as well as metallic and fluorescent inks. These are called spot colors.Six colors CMYK, O, G can also be used instead of CMYK to get wider gamut. This process is called Hexa chrome printing.
4. How many types of offset printing are there?
A. There are two types of offset printing.
1. Web offset: An offset process in which paper is fed in the form of reel is called web offset printing. There are two types of web offset printing
a. Cold set web : A process in which the ink dries by absorption and air.
b. Heat set web : A process in which the ink dries by heat.
2. Sheet fed offset
a. Sheet feed offset : An offset process in which paper is fed in the form of sheets.
b. UV offset : An offset printing process in which UV curing inks/ hybrid inks are used for printing on non absorbent substrate.
5. What is meant by substrate? What are the substrates that can be used for printing?
A. Printing substrate is the generic term for materials on which the printing takes place. Paper is the most common type of substrate.Plastic materials can also be used for printing (U.V. printing).
6. What are the kinds of papers on which printing can be done?
A. Art paper – Gloss · Art paper – Matt · One side coated paper · Sticker paper · Light weight coated paper · Maplitho paper · Creamwove paper · Natural shade maplitho · Kraft paper · Pulp card · Coloured printing papers · Coloured pulp cards · Buff card · Strathmore paper · Ivory card · Duplex Board Grey back · Duplex Board White back · Straw board and many more...
7. What are the different sizes in which the papers are available?
A. Commonly available mill sizes are· 23" x 36" · 30" x 40" · 25" x 36" · 31.5" x 41.5" (Duplex Board)
8. What is GSM? How is GSM measured?
A. The term GSM is used while calculating the weight of paper or board. This is measured in grams per square meter (g/sq.m). The GSM varies from paper to paper depending upon the thickness (Caliper) of the paper.
9. What are different types of coatings?
A. Coating is the thin protective layer which is applied to the paper after printing. The coating can be applied either online or offline. Different types of coatings are:
· Silk coat
· Matt Coat
· Gloss coat
· Aqueous varnish
· Scuff proof varnish
· Picture varnish
· Full UV – laminations / Spot UV
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