Sunday, November 8, 2009

Silk screen printing

Step 1
Create your artwork. If you don't know how to do that, sketch out the general idea. Sit down with your screen printer to work out the details. If your screen printer can't create your artwork, find a graphic artist.

Step 2
The screen printer will review your artwork and discuss the type of garment you want to have it printed on. Most people who print garments will have a supplier for apparel. If you're not sure of the type of apparel you want, ask your printer. They will have ideas for you. It is also acceptable to take your own. If it is something other than 100% cotton, there might be a slightly higher fee for the ink because other fabric may require ink additives.

Step 3
Bitmap image - Has pixalated edges. Once you have settled on a garment and the artwork, the screen printer will go to work. The first step is to prepare the artwork to be burned on the screen. Artwork that is received in a bitmap format (giff,  tiff, jpeg), will need to be vectored. There is a big difference between bitmap and vectored art. We were taught Bitmap=Bad, Vector=Good. Vectored art has clean lines while bitmap has pixels. The larger you make bitmap art, the more jagged the edges get. A vectored image can be changed, a bitmap can't.

Step 4
Screen Printing is labor intensive. It involves coating a screen, burning the image and applying the ink.
1.   Screens are coating using emulsion or capillary film. Both involve drying time.
2.   When the screen is dry, the artwork is burned into the screen. The process involves creating the artwork, putting it on a laser paper, exposing it, and washing it out. One of the really nasty parts of this is the wash out. If the screen is not coated correctly, parts of the design will wash out and the process starts again.
3.    When you have a perfect screen, it is time to screen the shirt. If you are doing artwork that involves two or more colors, a screen must be burned for each color.
4.    The inks used for screening differ with the fabrics. They also change based on the desired texture. Puff paint is really fun to work with and I like the foils.

Step 5
When everything is ready, it's time to apply the ink. If it is a 2 color process, the bottom color goes on first. You pull the ink across the screen leaving one coat. Most require 2 pulls to make sure that the ink on the shirt is consistent. The ink is then flash dried. This cures the top portion of the ink so the next color can be applied. You change the screen and pull the ink for the other color.  Again, usually two pulls. The top layer is then flash dried. The shirt is pulled from the platen (form where the shirt sits for printing) and dried.  Drying generally is 40 seconds. Again, different inks require different drying times.


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