Lithography

Lithography can be a difficult process to explain. You can use a grease crayon to draw an image on a stone or on an aluminum plate. You can use the computer and print images on clear film, which you then lay on top of a photo-sensitive plate. You expose that plate to light and develop it, and print using those plates. There is also a computer process in which you can print plates directly from a special printer. The image that is left on the stone/plate is receptive to ink, while the non-image areas are receptive to water.

When the stone or plate is ready with the image, you have to roll it up with ink. The process usually involves wetting the stone/plate with a damp sponge. Then you use a dry sponge to wipe away most of the excess water, and then you take a roller that is covered with ink, and roll it over the image. Then you go back through the process again, wetting the image and rolling, until the image is inked up enough to print.

For me, one of the more difficult aspects of lithography is making sure that the ink is "just right." It can't be too loose, and it can't be too tacky. If the ink isn't perfect, then when you go to roll the image up, it won't work the way you need it to. It can make a mess out of your image, or print it too lightly. Until you find the right mixture of ink, you'll often have to go through the process of cleaning off the plate and starting again with a different mixture of ink.

After rolling the stone/plate up with ink, you lay the paper on top of the image. Then you cover it with a backing sheet, to give it some padding, and cover that with something called a tympan. Then you're ready to run it through a press. The lithography press has something called a scraper bar. This scraper bar runs over the tympan and puts pressure on the image, and the ink transfers from the stone/plate to the paper.

If you want an image that is more than black and white, then it involves printing on the same sheet of paper numerous times. With the computer processes available now, it is fairly simple to have an image on the computer, and separate it into 4 colors on the computer. This gives you 4 different plates, and when the cyan, magenta, yellow, and black layers are printed on top of one another, it creates the full-color image that was originally seen on the computer. However, registration is crucial to getting a good image. Since you're printing on the same sheet of paper a number of times, if you shift the paper the slightest amount in the wrong direction, the colors will not lay over each other the way they are required to, and the image will not look right. To solve this problem, you mark each plate with "registration marks." These are basically lines that help you line the paper up.

So that pretty much describes the process of lithography. It can often be more difficult than it sounds. Depending on what you're doing and how many prints you plan to make, it usual helps to have at least 3 hours set aside for printing. It usually helps to have more, just in case things don't go as planned. It can be a crazy process at times, yet somehow I'm drawn to it. If any of this doesn't make sense to you, or you're interested in hearing more, please feel free to email me!

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