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  • DISCHARGE PRINTING

    We had a great question from a customer a few days ago and it got me thinking about possible complications when printing with discharge. Have you noticed your ink drying in your screen even when you keep it flooded? I checked in with Chuggins for a bit of clarification on why this happens and what you can do about it! Try adding 5%-10% water and possibly even the retarder by CCI. Always keep an eye on your shop humidity and keep temperature conditions controlled. Did you know that an underexposed screen can even dry out the ink a bit?!

    What issues have come up when you're printing with discharge? Are you a pro and have the process nailed down? We want to hear from all of you!! Post your questions and comments below so we can help all printers perfect their art, but first, let's discuss how discharge works...

    Discharge agent is a compound molecule. That compound is Zinc Formaldehyde Sulfoxylate. The discharge process begins from high heat, either during flashing or curing, breaking apart the activator molecule. Once the activator is in its separate components, the formaldehyde attaches to the fabric dye and breaks the dye molecule. It's this process that removes the color from the garment you are printing on. However, not all dyes react well and are considered “nondischargeable”. So check with your garment manufacturer for a dischargeability rating chart.

    After the garment dye is removed (this process happens at 250°F) you need to continue to heat up the ink layer and get a FULL cure of your entire ink layer. Water-based ink cures once the entire ink layer is at “cure temp” and it holds at that temp. 320°F is the target temperature here in the U.S. At this temp you need to hold at or above 320°F for 20-30 seconds. If this means that you need to keep the garment in the dryer for 3 minutes to reach 320° and hold at or above that temp for 20-30 seconds, then that is how long you need to keep your shirt in the dryer to achieve a durable print.

    At the end of the discharge process and during cure, the formaldehyde combines with the sulfur to create an inert molecule. As always, make sure you vent all air from the dryer to the outside. Some people have an itchy or swelling reaction when handling the discharge agent, what they are reacting to is the Sulfur in the activator. About 3% of the population have a sulfur (sulfa) allergy.

    If you are unable to keep your garment at those cure parameters, you can add Warp Drive to your ink. When you do this, you need to make sure that a FULL discharge of the garment happens. As the full discharge of the garment only happens after you have removed all of the water in the ink and the ink reaches 250°F, this is a great indicator that you have met all the parameters needed for the Warp Drive to activate.

    As always, test before running production.

    Click image for larger version

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