It's true: Colors do change with screen printing. Find out why and what you can do about it.
Those who think that mesh count is the only variable that affects the ink-deposit thickness are in trouble. Both the thread diameter and weave (plain or twill) can substantially affect the ink deposit as well. Mesh suppliers provide a number of specifications as to how their products will perform, and one of the most important is theoretical ink volume (listed by some manufacturers as "ink thickness" or "theoretical ink deposit"). This indicates the amount of ink that will pass through the mesh under given printing conditions, generally shown in cubic centimeters per square meter. On the specification sheet you get from your mesh supplier, you'll see a single value (in microns) that shows the wet ink-deposit thickness for each mesh they sell.
You can use this specification in a number of ways--for example, to calculate the amount of ink you need for a job (see "How Much Ink Do You Need?" Screen Printing, April 2000, page 36). Most importantly, you can see the dramatic difference in ink deposit between two seemingly similar meshes. Take two fabrics with a 390-threads/in. (150-threads/cm) mesh count, one with a 31-micron thread diameter and one with a 34-micron thread. The two meshes will have wet ink-film thicknesses of 11 and 6 microns, respectively. Simply stating "390 mesh" on your work order could lead to a tremendous difference in ink-film thickness and, consequently, a large variation in color as well.
The weave of the mesh isn't as big an issue today as it was a decade ago. You are far less likely today to get a twill-weave mesh when you were expecting a plain weave, although it still happens occasionally. Typically, a twill weave will vary 10% in the theoretical ink volume of a comparable plain-weave mesh, not to mention the fact that it would hamper your ability to print fine details.
Did you enjoy this article? Click here to subscribe to the magazine.