How to Screen Printing with Discharge Inks
So you want to learn about the wonderful world of discharge screen printing. Well, you've come to the right place...the following technical information has been compiled from over 5 years of hands on experience with large and small volume screen printers and popular, well known clothing lines.
If you are new to screen printing, you may want to start off printing with plastisol or standard water based inks before attempting to print with discharge inks. There are more steps involved in discharge printing and many more variables that can make using these inks daunting for the average newbie.
Table of Contents
- Everything you Need.
- Screen Selection and Mesh Count.
- Mixing Ink and Pantone Color Matching.
- Curing and Dryer Specs.
- Clean Up and Disposal.
- Final Considerations.
What is Needed
The basics of discharge printing are not that much different from traditional screen printing. You pull (or push) the squeegee in exactly the same way, you develop the screen stencil the same, and you cure the same. The differences are subtle but numerous. Below is a list of what you need to get started....
- Discharge Base
- Discharge Agent (zfs)
- Water Based Pigments
- a Screen (125-160 mesh)
- Water Resistant Emulsion (or emulsion hardener)
- a Squeegee (70 duro or harder)
- Conveyor Dryer
Screens, Mesh and Stencil Creation
Discharge inks are very hard on standard emulsions. The inks can begin to breakdown your stencil very quickly, often in 20 minutes or less. To prevent this from happening, you can use a water resistant or discharge specific emulsion or an emulsion hardener.
- Discharge Emulsion: There are many emulsions designed for discharge printing. These emulsions are great because they provide protection from the harsh effects of discharge inks right out of the bucket. Unfortunately, these emulsions are often very expensive and can be extremely hard to reclaim.
- Emulsion Hardener: Using an emulsion hardener is a great way to add discharge printing to your existing production without having to change emulsions. You can use your standard emulsion that you would use for plastisol printing and expose the screen in exactly the same way you do for a standard job. After the screen is burned, washed out and ready for tape, simply wipe emulsion hardener on both sides of the screen and image area and allow to dry. The screen are still reclaimable and can be used for discharge, water based and plastisol inks.
When it comes to mesh selection, you should choose a mesh between 125 and 160 with 160 mesh being ideal. You don't want to choose a more open mesh count because the inks are slightly watery and edge definition can be lost on lower mesh counts. Higher mesh counts cause problems because the inks will dry in the screen. Discharge inks can be printed through higher mesh with the addition of Softener and Wetting Agent.
Sample Discharge Prints
Standard discharge clear and discharge white.
Mixing Inks / Pantone Matching
Mixing and color matching with discharge inks can be the most difficult and frustrating part of the process. All fabrics discharge slightly differently and this can cause problems for keeping consistent colors across an entire print job. This can be especially true if you are printing on several different colored garments. It is always a good idea to test the garment in each color for each color of ink you will be using.
Discharge ink is available in several flavors...
- Discharge Clear: The standard discharge clear can be used as an underbase, a stand-alone ink 'color' or mixed with colored pigment to create a discharge color. Which ever way you decide to use it, you will always need to add the discharge agent to the ink in order to get it to 'bleech' a dark fabric. If you use the ink as a stand-alone ink, it will simply remove the dye from the garment and leave the natural or white color showing after the ink is heat cured. When mixed with color pigment, the resulting ink will produce colors with a vintage look.
- Discharge White: Discharge white is used as a stand-alone white for printing white and is not intended for use as an underbase. The ink is easy to print and produces bright whites on dark garments without the need for a flash. As always, this discharge ink needs to be mixed with discharge agent.
- Bright Discharge Clear: This is a newer product made by Matsui Intl. The bright discharge clear is identical in use to teh standard discharge clear but produces brighter, more vibrant colors. The colors produced with Bright Discharge can have tonal ranges similar to plastisol inks without the heavy hand or 'plastic' shine. This base is recommended for use with the Matsui Pantone matching system. *any colors that contain more than 1% black should be mixed with Standard Discharge Clear
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