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Discharge Printing on Cotton Garments

Photo by @Rodney - printing by ForwardPrinting.com

In each of my classes around the country these days, one or more students will ask specifically about discharge printing. They’ve seen it, they like it, but have little idea how it all works. In brief, discharge ink will “discharge” the dye from a garment, leaving behind the original fabric color. This discharge effect occurs under forced air and heat, and is only visible on the exit end of the dryer belt.

Discharge printing as some believe is not actually a new innovation in the industry. As with many processes in screen printing, discharge has come in and out of favor over the years.

Pros and Cons of the Process
On the plus side, discharge printing gives you a beautiful effect on cotton shirts. Discharge is the look you see in all the upscale shops at the mall catering to teens and young adults. These prints have virtually no hand (feel) on the finished product.

On the negative side, you will have difficulty seeing pinholes and ink dried in the screen until the shirt passes through the dryer. Also, discharge ink can have a strong odor, much like rotten eggs. On prints that go over collars and seams, the thread will not discharge unless it is cotton… and most t-shirt manufacturers use nylon thread unless the shirts are specifically manufactured to be dyed.

Discharge inks contain zinc-formaldehyde which means a garment must be laundered prior to wearing. Your options are to place a printed disclaimer to launder before wearing with every shirt, or you must launder the garments yourself before shipping. Therefore, this product is not suitable for children’s apparel.

Discharge Ink
Most discharge ink is water based. Generally, you will start with a discharge base and then add pigment colors. Printing with just the discharge base will give you the original shirt color, which is a very popular effect. Adding pigment to the discharge base will produce that color on the shirt. Again, the effect is only visible at the exit end of your dryer.

Discharge ink in most cases will come as a clear, water based binder. You add an activator prior to printing. For colors, pigment is added to this activated mixture.

All discharge prints will look dull or like water on the shirt until you send them down the dryer belt. Forced air heat will activate the discharge process. If the shirt is not fully discharged on the first pass through the dryer, it’s okay to send it down the belt again for a richer effect.

Matching colors exactly on anything but PFD shirts is virtually impossible with discharge ink, due to the original color of the fabric, and the amount of discharge achieved based on the fabric dyes used in the original garment. Some fabric colors discharge better than others. Kelly, purple and royal blue are particularly difficult for achieving a full discharge.

Once mixed, the activated ink will have a pot life (usable period) of six to eight hours. After your printing window runs out, the ink is useless and any excess must be disposed of. Only mix what you need for each job.

As with all inks, follow the manufacturer directions for your ink brand of choice. Instructions will be similar but may vary from brand to brand.

Cotton Garments
Unless a garment is PFD (prepared for discharge), which means it is bleached white and then pigment dyed, the color of your original fabric will vary. When making dark shirts, the fabric does not need to be perfectly white before being dyed to a dark color. The original fabric will be everything from shades of yellow to shades of pink. If you’re okay with whatever color you end up with for the graphic, and many designs work perfectly fine in this scenario, then discharge will give you a soft hand and very distinctive effect on any 100% cotton garment.

PFD garments are not only bleached white and then dyed, these garments are also made with cotton thread at collar, cuff and hem. If you’re looking to fully discharge prints over collars and seams, you’ll need to use PFD garments. Otherwise, color threads will show through your prints. Polyester threads in traditional garments will not discharge and will make it impossible to properly use discharge ink over seams and collar as is popular today.

PFD garments are more expensive to manufacture and therefore more expensive for you to buy and print. In the end, it’s all a matter of the effect you are looking to achieve. PFD shirts are available from many wholesale blank garment suppliers.

Terry Combs is a 30+ year veteran of the screen printing industry. He is an industry teacher and consultant through the website TerryCombs.com, offering hands on and online classes. And, he is the owner of the screen printing supply company, GarmentDecoratingSupply.com.

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Hello Terry, I just read what you wrote about discharge and was wondering if you have to flash the discharge under? Also, what does a 50/50 shirt do when discharged? One more, How much discharge do you add to colors or how much color(pigment) do you add to the discharge? Thanks /Che.
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