ImagesMagUK_April_2022

www.images-magazine.com APRIL 2022 images 77 TIPS & TECHNIQUES STEP-BY-STEP: DISCHARGE PRINTING Test your garments Not all fabrics are suitable for discharge printing. It’s always a good idea to test out the garments you are going to print beforehand. Remember, only cellulosic fibres like cotton can be printed with discharge inks, and they need to be dyed with reactive dyestuffs – but this doesn’t mean you can’t use blends, which can create a nice vintage look where the polyester fibres don’t discharge. Another consideration is the colour of your fabrics – some may discharge better than others, which is another good reason to test prior to production. Discharge ink is extremely versatile when it comes to the type of artwork you can screen print, ranging from solid, vector-style designs to photographic halftones and detailed designs. We chose a playful motif with plenty of colour to show off the bright effects you can achieve with discharge inks. We recommend using 43-62T (110-158) mesh screens for solid areas and 77-90T (196-230) mesh for halftones when printing with discharge inks. As this design was made up of completely solid print areas, we used 62T (158) screens for all colours. For this guide we used four different colour shirts – 100% cotton black, 100% cotton navy, 90% cotton/10% polyester heather blue, and 50% cotton/50% polyester grey – to provide a nice range of results and effects. Discharge LO, like other discharge inks, is a ‘two-pack’ system and uses 6% activator (Activator AB) which is mixed with the base ink before printing. Following activation, the ink should be left for 10-30 minutes to dissolve and has an active life of up to eight hours (depending on environmental conditions). To avoid wastage, only activate the amount of ink needed for your run (usually 1-2 kg per screen). Always keep activated ink next to the print station in a sealed container. Once we had selected the five different colour references for our design (plus Super White for the white areas), we were able to mix the colours using MagnaPrint Eco-Pigments and the Discharge LO ink system. We generated the recipes using the MagnaMix software and selected our required quantities, then used an automatic MagnaTint pigment dispenser to add the colours to our ink pots. The ink then needs to be thoroughly mixed. If you don’t have a dispenser, you can weigh out each pigment – MagnaMix provides accurate recipes for thousands of different colours. When setting up the screens on your press, make sure that there is around 3-5mm of off-contact distance between the mesh and the garment. We used a medium 60-90-60 shore rectangular squeegee and set the blade angle to 15° (10-15° is ideal). Screen order in the machine should go from smallest to largest print areas and white should always be last. This is to avoid pick-up during the screen printing process: as white is the brightest colour it would stand out more on successive prints if white discharge ink was accidentally picked up from the garment onto a later screen. Putting it last avoids this. 1 2 4 3 5

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