Guide to printing students -10

Guide to printing students
-Few objective Questions and answers- 
Written by : N.R. Jayaraman
Pre note:-
The articles are meant to help the students gain knowledge and effectively compete in the interviews and nothing else. Please note that these are not to be published by anyone for commercial purpose without the written permission from the author since the theme and illustrative examples have been compiled exclusively by the author for the benefit of the student community. THIS WILL BE PERIODICALLY PUBLISHED.

52) What is the standard norm normally followed for calculating the machine life?

53) What is the standard thickness of Offset and Intaglio printing machine Blankets ?
The standard thickness of Offset Blanket ranges from 1.65 mm to 1.70 mm while the standard thickness of Intaglio blanket is 0.5 mm. While the above are standard ones, machine specific thickness blankets are also made available by the manufacturers to suit their machine configuration.

54) How will you work out the weight per ream of paper ?
To find out the weight of paper per ream the following formula is used:

55) What is GSM and how will you work out the GSM of paper ?
GSM means grams per square meter (gsm), which is the basic weight of the paper used. In metric system the mass per unit is expressed as GSM. In other words, a square meter of a specific type of paper will weigh a certain number of grams. The GSM indicates how dense the paper is and help the printer decide suitable paper for suitable job. The general principle is the higher the GSM the thicker the paper will be. 

GSM also help  in calculating the weight of a ream of paper so that the cost of the paper  can be worked out as the paper is always supplied in weight and charged accordingly. The GSM is determined by weighing a known size of paper after conditioning the sample for 24 hours in ideal press room condition having 23°C temp and 50% Rh .

To find out the GSM of the paper the following formula can be used:

1000  x  100000
Weight of paper in Kg  x   length  x  width of paper in mm  x   500

To find out the weight in Kg of the paper the following formula  can be used:

GSM  x  length  x  width of paper in mm   x   500
1000 x 1000000

56) What is fixed cost in printing industry?
Costs that remain constant regardless of how many no of sheets are printed for a job. For example the costs incurred on Copyright fee, authors fee, preparation of manuscripts, copy writing and editing, % overhead to be charged, photography and designing etc which in effect are one time invested cost. Irrespective of how many copies are printed, those costs does not change.

57) What is Ghost image on print?
Faint image seen on a printed sheet where it was not intended to appear may be termed as Ghost image. The Ghosting occurs when the printed ink film excessively penetrates to the back side of the same sheet thereby disturbing the appearance of the backside printed image and vice versa especially where halftone images appear. One of the major reasons for this defect is use of thin paper, excessive penetration of ink into the paper due to defective ink matching to the paper for which it was intended, fountain solution emulsifying the ink in wet offset printing etc. 
To be continued.............11