By Dan Bouchard

Creating your drawings in color can be a real benefit when viewing your drawings on screen, or when printed with a color plotter, but it can be a real nightmare when printing on a black and white machine.

Very often we are presented with plans to print that have been designed in color. The easiest way to reproduce these would be to print them out in color. However, this is usually not a feasible option for a large quantity of plans. Additionally, most contractors would prefer to work off of black and white plans.

High speed black and white machines are just that, black and white. They use black toner not ink. When presented with a color plan to be printed in black and white, we have two options. We can either, 1. Print in true black and white, meaning every line will be printed black, or we can 2. Print in grayscale which will attempt to print the colored lines as a screened percentage of black. This is somewhat of a simplification, but for our purposes here it will do.

In number one, our software will look at the image and very simply print everything it sees as black. This means that any distinction that the draftsman was attempting to create by using colors is completely lost. The only real way to compensate for this would be to use different line weights for each color. This would at lease help distinguish between the lines that were in color.

In number two, our software will attempt to render each color as a screened percentage of black. Darker colors such as Red and Blue will have darker screens and lighter colors such as yellow and green will have lighter screens, and while we have some control over this, the results generally are not what the draftsman was looking for. I would suggest only using a dark blue or red in this case.

Many times we will receive a drawing that the draftsman says was drawn using only black. When we examine the drawing however we realize that in an attempt to create lighter lines, a gray line was used. It is important to know that gray, is a color, just like red or green or any other color. Given this, the same rules apply as above. But wait, the draftsman complains that when he prints out the check plot on his machine, it prints fine. This is true because nine times out of ten he is using a color inkjet machine for his check plot and gray is not rendered as a screen on an inkjet machine. It is a combination of red, blue and black. If you want to get a better idea of how your print will look, you should set up your printer to use ONLY black ink to print.

Unlike inkjet plotters, high speed high quality toner machines used by most reprographic shops were designed to print very fine lines, actually as fine as .001 accurately. This is a great advantage for those draftsmen who use a variety of line weights, but it can result in lines that are very hard to see for those who draw in color. The results will also be much different than those that you get from an inkjet plotter which cannot produce lines as fine.

Finally, most reprographic shops are perfectly willing to print test prints for you to work with. I usually suggest to my clients to create a sheet with all of their line weights and colors on it. Send it to us in different formats and we can print it for them so they can see exactly what each line will look like when printed. The little time it takes to do this could save hours of time and stress when the day comes that the drawings are due out.

Filed under: Plotting