The published articles are meant to primarily educate the students in printing to supplement their knowledge in the field of Printing. These are not simple Glossary of printing terms, but to the extent possible every term has been explained in brief so that it can be of some use to the students who appear in some sort of examinations and interviews.
I served the Printing Industry for over 40 years
in various capacities, a major part in an Security Printing Organization. In order not to waste the printing and paper related knowledge which I gained over years, I decided to keep them in public domain for the reason stated in prepara. Most of the illustrations - over 90% - have been generated by me to explain the terms suitably.
While I am not sure to what extent the published content will help, if the content is going to be of use to some one in some manner, I will be greatly satisfied.
Your views may be sent to me ( for my record and correction wherever needed.



- Over 400 terms-

Click on this line to read from 'A'

Wednesday, October 10, 2012

Alphabet R

1. Ream: A term that denotes 500 sheets. The Paper supplied by every mill will be in lots of 500 sheets or 20 quires of 25 sheets each of the same quality, and same size of the paper totaling to 500. This 500 is the unit measurement called a Ream of paper. The quantity 500 is fixed for easy calculation and physically handling even the bigger size of paper.
Previously some the mills used to supply a ream containing 480 sheets or 516 sheets. There was no specific reason for packing in the said manner and was probably packed according to the convenience of the Paper mills as the billing was always on per M.T. and there would be no loss even if they supply 480 or 516 sheets per ream pack. Since accounting the 480 sheets or 516 sheets became difficult for calculating the  paper requirement, the DIN 6730 standard for Paper and Board has been universally accepted as a standard Ream packing that stipulated 500 sheets per ream.
2. Resolution: Resolution denotes the quality of the image as seen in a Print or Digital Images used for printing purpose. The resolution of a image in print is expressed in terms of  halftone ( not line work)   screen used in the reproduction. The resolution in the Digitally  generated image is  expressed by Pixels. One must know the difference between these two images.
See the scanned images produced with different resolutions in Digital Process. While the clarity of the images have increased with higher resolution, the shape of the Pixel have not changed in any of the images. All images show the Pixels as square dots of uniform size only. The only difference is the size of Pixels that have decreased in higher resolution images, i.e no of Pixels per square inch is found to be more.
On the other hand if you see the Halftone print you can see that the image has been formed with varying size of dots in the same image, and all dots and squares are not uniform in shape and size like Pixels.
In the case of Halftone images, with each phase of resolution, the pattern and the size of the dots that governs the clarity will keep changing. The resolution of the Halftone screen that causes the clarity changes, are expressed as lines per inch which is the number of lines of dots in one inch, measured parallel with the screen's angle. This resolution known as the screen ruling, is expressed as 150 lpi, 200 lpi etc.
Similarly the resolutions of the Digital images are expressed in terms of number of Pixels per inch (ppi) or as Dots (Pixels) per inch. 

The Resolution of the halftone screens for various printing processes in general are:
Offset or Letterpress printing : minimum 85 line screen to 250 line screen. 
The coated stocks print up to 400 lines per inch screen images.
Laser printing : 300 to 600 dots per inch.
Screen printing : 45- 85 lines per inch.
However there is no such fixed resolution % stipulated in the case of Digital Images.
3. RGB: The Colored images formed by the Digitally generated images are based on the additive color theory whose basic colours are Red, Green, Blue which further creates secondary and tertiary colors. The Red, Green, Blue color space approximates the way the human eye works and produce all other colors visible to the eyes. The three additive colors Red, Green and Blue are therefore nicknamed as RGB.
4. Rainbow Printing: Read under Prismatic Printing
5. Rainbow Fountain : Putting different colors of ink in the same fountain with a small stopper in between each color to prevent them getting mixed up in the ink fountain itself, and then supplying the ink to the roller chain including oscillation roller which merge the colour edges to form a pattern of Rainbow . The Ink duct that carries more than two colour ink is called Rainbow Fountain. Read the function in detail under Prismatic printing. 

6. Rag Paper : The good quality of  paper for printing is made with high content of cotton rags, cotton clothes or cotton linters. The paper made with such pulp is called Rag Papers.  The fibers on the Rag paper are longer than the wood pulp paper and therefore Cotton Rag made paper is viewed as more durable paper. The Rag paper is also called Acid free paper because their Ph is neutral. Normal paper like newsprint, note book paper, paper used on computer printers etc are mostly made of the cellulose fibers or wood pulp. Paper used for printing the Currencies are made with pure cotton and linen pulp and this will indicate how important is the Rag paper. One of the biggest advantage of using Rag paper is the that it does not disintegrate easily. This is one unique quality of the 100 % pure Rag paper used for printing the Currencies. For other printing purposes where durability is important 10 to 25 % Rag content Paper is supplied.
7. Recycled Paper : The Paper manufactured by reprocessing the discarded, old and used paper is called the Recycled Paper. Paper recycling is the process of converting the waste paper into new paper recovering fibers from them. The Recycled Paper is used in many areas including   use as writing, typing, photo copying, Newsprint Papers and for making gift articles, Paper trays, Egg baskets, Greeting cards, Cover papers, Corrugated Boards etc. The Recycled paper is also used for making tissue and sanitary papers. Since converting the Recycling the Paper into  high quality paper is a costly process, the Recycled paper is used for limited purposes as stated above .
Which are the paper that are used for recycling to convert them as re usable paper ? The Paper trimmings from the Presses, the waste and torn paper from the paper mills and printed material like News Papers, Magazines etc which are however bleached to remove the inks from them before re using for manufacturing white paper.
However the trimmings from the 100 % rag content paper from the Currency note manufacturing paper mills are re-pulped in the mills itself and mixed in small proportions with the good pulp for making paper. The reason for mixing in small proportion is that the recycled paper will have shorter fibers length compared to the longer fiber paper manufactured, and more %  of the recycled paper will reduce the strength and alter the other properties of the paper.
The contaminated material such as paper used for food packing, plastic, metal, and other trash, etc are to be separated from the waste paper load collected from various sources as they can not form pulp for manufacturing the paper.
Contaminated paper and printed paper waste which cannot be recycled are composted, burned for energy in industries where industrial boilers are in operation etc and or land filled.
The waste paper load that includes the Corrugated boards and Kraft paper are sorted to separate them as the pulp made with them will not produce durable writing paper. More over originally made with wood pulp, they will cause Off shade instead of white paper. On an average only 70-75 % of the paper waste is converted as re usable paper for above said purposes. 

The few steps involved in recycling process are:
Collection from various sources
Waste paper segregated as printing paper and corrugated boards and Kraft papers.
Sorted paper lots crushed or trimmed to pieces
Adding certain chemicals the trimmed lots are thoroughly washed and pulped
The Pulp is filtered through sieved screens of various size holes to remove un noticeable plastic and other impurities
The Paper thus filtered is colored with dyes to make colored paper or if white paper is to be produced, they are bleached. Depending upon the paper manufactured, the processing is arranged with suitable chemicals and materials.
Once the pulp is ready it is pressed into the Paper making machine and Paper made. 

...........Additions to alphabet R to be continued under R/2

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