Screen Printing with Discharge on a 50/50 Blend
Creative print engineering to avoid dye migration and over seam screen printing.
Recently, we used the SanMar Port & Company Core Fleece Sweatshirt Tote to make swag bags at our Water Based workshop. These totes were a great hit because of their unique style and cozy garment feel. However, due to its 7.8-ounce, 50/50 cotton/poly fleece and pocket construction, we found decorating this tote using traditional screen printing practices a little more challenging than traditional totes because of placement and dye migration. So with this blog, we will walk you through the technical steps of how we successfully problem solved and screen printed these using Matsui’s Alpha Series of Discharge.
Specifying the Print
A great finished product takes into consideration the garment, design, and print engineering used to decorate it. First, we conceived and mocked up a WB Camp repeating logo designed to print on the pocket and bleed over its seam. As screen printers, we all know that a great design in and of itself is not enough to make a great screen print. So after the initial design, we shifted our focus to coming up with an ink and production strategy to make the design look good and easy to print and repeat.
Normal plastisol would have dye migration issues and not achieve the overprint on the seams we desired. To mitigate these variables, we decided to mix a custom discharge color using the white Alpha Discharge from Matsui and adding 2% black pigment to create a medium gray. Matsui’s Alpha Series is an RFU discharge water-based ink system that can be printed either as discharge or RFU water base (with the exception of the white, which has a heavy pigment load and can only be printed as discharge). Due to this construction, it’s also designed to sit more on top of a garment versus penetrating through it completely, which is what we needed since the fabric was softer and thicker (remember, more hoodie-like fabric versus the traditional canvas tote). For this application, we thought it would work well allowing the gray color of the ink to be dark enough to mitigate any dye migration issues and the discharge to be thin enough to overprint the seam of the front pocket.
Screens and Print Placement
We have mentioned the overprinted pockets a few times, let’s dig into how we achieved this. Pockets can be either printed over a sleeve or custom platen and tacked down or on contact printed. We decided on contact print. We also inserted a cardboard sheet to protect the background fabric. We used a 157 hi-dro mesh thin thread screen with a PHU WB water-resistant emulsion on a GSF frame with great tension. The ROQ YOU was set to a medium angle of about 12 and an increased pressure to 60 to get enough ink down the first pass. This would allow us to on-contact print in one pass, so the garment did not have a chance to move during the print process. Finally, we used the lasers on the ROQ automatic screen printing press in order to correctly align and place the design.
With proper alignment and a few adjustments, the print dialed in nicely, and we were able to print over 100 tote bags for WB Camp attendees and vendors in just under 15 minutes, a little slower process due to the complexities of the design and substrate, but it executed flawlessly.
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