All About Discharge Inks

All-over and soft hand prints are all the rage right now. Lightweight fabrics and more fashion oriented designs make discharge printing a must for most professional screen printing shops. Adding discharge printing to your current work flow and ink department can be easier than you might think. This tutorial is designed to help lessen the learning curve with discharge printing and help you understand some of the basics.

A Little Background...

Discharge printing is not new. It has been around for many years but only recently has the process become popular. Brands like Ed Hardy, Affliction and The Saint Sinphony have helped to spark the revival of discharge and water based inks. Over the past 3 years, clothing brands and screen printers of all shapes and sizes have added discharge printing to their offerings. Now is the time to get started with this easy to use, fun and valuable printing technique!

What is Discharge?

Discharge is a chemical process where the ink destroys the dye used to dye the garment a specific color. It basically removes the dye's ability to reflect the color. It is almost like the ink bleaches the fabric where ever it is printed. This leaves the natural colors of the fabric showing. The color of the fabric is usually a 'natural white' or 'off-white' color. The process takes place during the heat curing process of a standard screen printing run. A typical cure takes place at 330-340° @ 40-90 seconds (these numbers can vary depending on your setup).

 

Health and Safety Issues

Even though discharge inks are water based, there are some health and safety issues to consider when printing with discharge inks. The active ingredient in discharge ink is called Zinc Formaldehyde Sulfoxylate or ZFS. The key part of ZFS is the Formaldehyde. The level of formaldehyde in ZFS is very negligible and almost untraceable. Use of discharge ink and ZFS is not under government regulation but you should still take precautions when handling and printing with these inks. For more information on formaldehyde please download the OSHA Formaldehyde Fact Sheet.The following guidlines are strongly recommended...

• Ensure the printing environment has proper VENTILATION and CIRCULATION.
• Never leave discharge agent (ZFS) uncovered when not in use. Make sure to immediately clean any spilled agent.
• Wear gloves or other protective clothing when handling discharge agent.
• Do not use a flash dryer or heat gun to fully cure discharge ink. This produces too many fumes.
• Wear a respirator if fumes are or become a problem.
• Use as little discharge agent as possible in your mixture of discharge ink.