Water based screen printing inks are air-dried. This is good because you don't need to have special drying equipment like conveyor dryer for your printed shirts. Just flash dryer, heat press, heat gun or even hair blower can dry the prints. This also means that you can prevent dye migration from happening. Too much heating of polyester blend t-shirts will cause dye migration from the shirt fabric to the print ink. This will make your print color mix with shirt color and look bad. So, water based ink does have merits. But the most serious problem with water based ink is that it also dries quickly in your screens while printing which will ruin your prints and stop the production because the screens become unusable. This is especially such a big concern in hot weather region like here in the Philippines.
Although there is no one solution to completely prevent this, we can try various ways to minimize problems with water based ink drying in screens:
- Choice of Ink: Ink maker might have better ink for this issue. Ask them.
- Fresh Ink: Ink that is manufactured long ago will dry faster even if new. Also, keep water based ink in cool, shaded, humid area in air tight container.
- Retarder: Mixing retarder with ink can somewhat delay drying speed.
- Fast Production & Flooding: Ink won't dry fast if it's constantly moving. Make the interval between use as short as possible and make sure the screen is flooded during the intervals.
- Right Emulsion & Wet Screen First: Use correct emulsion for water-based ink. Before putting ink on the screen, wet the screen first with wet towel. This will help the screen not to absorb/dry the ink immediately when you put it in.
- Artwork & Mesh count: If artwork has halftones make them low lpi like 40 lpi. Also, use mesh count like 125 for halftones and 100 for solid spot colors.
- Humidifier: Use humidifiers towards the screens. Do not blow air to the screens with fans or aircon.
- Wet On Wet: If possible, print wet on wet to avoid heated platens and longer printing intervals.
What else do you do? Why don't you share your solutions with us :)