The silk screen printing technique, also known as screen printing, is great for printing on all kinds of surfaces and fabrics, including nylon. Common projects include printing nylon jackets, backpacks and fabric to be sewn into banners or shirts. Silk screening on nylon calls for attention to a few key details. You must use the right ink and printing technique for nylon. The printed fabric must be cured properly.
Open a digital graphic image file on a computer. Load a laser printer with clear vellum paper and print the digital graphic image on the it. The resulting print will look like a graphic image printed on a piece of clear paper. This is a film positive.
Step into a dark room. Coat a silk screen stencil on both sides with photo emulsion using a screen coating tool. Coat both sides of the screen using the sharp side of the trough on the coating tool. Do three strokes on each side of the screen. Use the final stroke on each side to remove excess emulsion. The result is a silk screen stencil coated with a thin but opaque coat of photo emulsion. Place the coated screen face down in the dark and let it dry overnight.
Cut a piece of foam rubber to fit inside the open side of the silk screen. Place it on a flat surface and put the screen over it. Place the film positive face down on the back of the silk screen. Put the 1/4-inch-thick glass on top of this assembly. Hang a halide light 18 inches over the glass. You are ready to expose the graphic image on the screen.
Turn on the halide light for seven to eight minutes then turn it off. Still in the dark, spray the silk screen stencil with warm water at medium pressure on both sides until the image appears. Check to be sure the image has completely appeared. Blot both sides with newsprint. Set the imaged silk screen stencil aside to dry in a will lit place.
Put the silk screen stencil in the clamps in a screen printing press and position the screen to print in the center of the shirt board, or other desired position. Tighten the clamps until taught.
Set the clamps to print "off contact" about one-eighth to one-quarter inch above the printing area. This means the screen will float slightly above the print surface. Loosen the bolt on the back of the clamp and pivot the clamp and silk screen to the desired off contact position. Tighten the clamp. Check to see if the silk screen maintains the off contact position. Off contact printing helps make clean prints on nylon.
Spray a mist of spray adhesive on the printing press surface, also known as the shirt board. Place a piece of test fabric on the printing surface. Mix a small amount of nylon bonding agent into some plastisol ink, about 10 percent of the total. Add ink into the silk screen. Pull the ink firmly across the silk screen with a squeegee to print the test fabric. If the proof looks good, proceed to print on nylon. Add spray adhesive after every few prints to the printing press surface. Clean all the ink out with mineral spirits when done.
Once each piece is printed, it must be cured at a minimum of 300 degrees Fahrenheit for 15 seconds or longer. Use a spot dryer or a conveyor belt dryer for this function. Do not over cure or the nylon will melt.
If your screen printing clamp has no bolt on the back that allows you to pivot it to the off contact printing position, try taping an ink mixing stick on the print board close to the clamp to force the screen off contact. If this is not possible, try taping a coin under the print arm that holds the clamp to force the screen into the off contact position.