Discharging is a chemical reaction that destroys the ability of selected dyes to reflect color. This reaction takes place with Union discharge inks when the print reaches 320 degrees Fahrenheit for a minimum of 90 seconds.

Only reactive dyes used on 100% cotton, and natural fibers are dischargeable. In the early stages of discharge printing Fruit of the Loom, Gildan, Anvil and Lee were the only major garment manufactures stating some color of their 100% cotton T-shirts discharged well.

Most textile printers are comfortable with plastisols and are familiar with the techniques of how to use them. Although a 100% water base discharge print yields the ultimate in softness, breathability and absorbency, prints produced by overprinting Union plastisols wet on wet through fine meshes over a plastisol discharge under base come very close without the problems of drying in the screen and the pot life associated with straight water base discharge inks.

The discharge process will produce softer feeling prints as well as bright colors on dark garments. The printer will also increase his production output because the absorbency of a discharge under base into the shirt allows the printer to print each subsequent color on top of the discharge under base wet on wet. To eliminate pick-up on screens overprinted onto the discharge under base printers may elect to flash cure the under base print.However, if printers decide to flash cure it negates part of the increased production advantages of this process. Re-died garments from shirt manufactures will not discharge. Purple and royal garment will not discharge because they are not reactive dies.

Are there special screen-making considerations?

Water-proof (not simply water-resistant) stencils are required for both the under base screen and each subsequent screen. Contact your emulsion supplier for his best choice to make waterproof screens that will resist breaking down during production when performing this process.

How do printing discharge inks differ from plastisol inks?