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Nov 1, 1996 12:00 AM
Many estimators say that it doesn't pay to estimate the cost of ink. The reasoning is they never know how much coverage there will be on estimating day. Therefore, estimators may as well include ink as part of the hourly rate or figure the cost of ink as a percentage of the cost of paper (see Estimating, page 82 in the October issue of AMERICAN PRINTER). Another method is to include a minimum charge. Even if it's a small job, charge $50. If it's bigger than a small job, charge more. How much more? Well, your guess is as good as mine.
A better way to go about estimating is to ask customers how much ink coverage there will be. They probably will not be able to express the amount in square inches. So speak in percentages. If they say 30 percent, we take the number of square inches of paper surface in the printed job and multiply that by .30.
A 16-page, 9 x 12-inch booklet would be calculated this way:
* 9 x 12 = 108 inches per trimmed page
* 108 x 16 = 1,728 inches of paper surface per booklet
* 1728 x .30 = 519 inches of cover page per booklet
* If there are significant bleeds, multiply 9 1/8 x 12 1/4
If the coverage is different when the actual job comes in, recalculate the ink cost. The markup for more ink than was originally allowed for does not need to be exactly the same as the original markup on the entire job when it was first quoted.
Computer-assisted estimating makes calculating ink far less tedious. As the specs are entered, the system is told how many colors will print on each side. Specs also include what paper will be used; the computer knows the paper surface. The system does the calculations needed to arrive at how many sheets, including waste, so it knows the number of sheets that will receive ink.
Computer programs usually ask what colors of ink will be printed on side one, what colors of ink on side two and what percentage coverage for each color on each side. Here, it is necessary to proceed with caution. Is the program thinking in terms of the press sheet size or of the trim size of the final job? Thirty percent applied to a 26 x 40-inch press sheet will be much more than 30 percent applied to a 9 x 12-inch trimmed booklet.
The same method for calculating black and match colors cannot be used to figure four-color process. In process printing, one ink prints on top of another, and then two more inks print on top of those. In sheet-fed printing, it is possible to lay down as much as 320 percent coverage.
One method for dealing with process inks works with square inches of picture rather than using 50 percent coverage for each normal halftone. The reason is that in process printing, the yellow halftone is almost always much fuller than the cyan and the magenta, and the black usually is much lighter (unless gray component replacement is being used).
Ink manufacturers' consumption charts show the number of thousand square inches of screen surface (not solid) that one pound of ink of each color will cover.
This kind of chart does work, but it makes it necessary to go through four complete calculations and is very cumbersome. A shortcut is to use a weighted average. It would show coverage for one pound of ink for all four colors together in the correct proportions. The chart is shown in Table 2. It then becomes necessary to use a weighted average for the price per pound.
As with all estimating, we cannot take charts such as these, which are based upon averages, put them to use and assume we are being accurate. The key issue is not how many pounds of ink other printers use, but how many pounds we are using. Press operators should report actual consumption. Then, the actual consumption should be compared to the estimate. If there is a consistent variance over period of time, the chart should be revised accordingly.
Don Merit, contributing editor and a production management and estimating consultant based in Burlington, VT