Today's we’re going to talk about how to prep and seal a silkscreen for screen printing, and some of the products that we use to do so.
Our goal when sealing a silkscreen is to create a seal that will last through months of intensive printing. Time is valuable, and we want to avoid the need for resealing screens after each project.
We start by taping off the bottom of the screen (print side down) using Rtape by Nekoosa Print Media. Rtape is specifically constructed for screen printing and is a polyethylene film with an aggressive acrylic adhesive. It forms a solvent-resistant dam which prevents ink leakage and it removes cleanly from the mesh without leaving any residue.
The tape is carefully applied so that it’s half on the interior side of the screen and half on the bottom. It’s important to create a tight, smooth seal. We use a baby squeegee and go over every inch of it to ensure there are no air bubbles or inconsistencies.
Once the bottom of the screen is taped across all four sides the screen gets flipped over. Before anything else happens we add painter’s tape just outside of where the Rtape lies. We’ll be adding lacquer blockout into this area, and we want the lacquer to extend ever so slightly beyond the Rtape to help ensure an effective seal.
We use Candoc Clear Lacquer Blockout 9500C G. Lacquer blockout is ideal for water based, poster, and enamel inks. This blockout dries fast, but is easily removed with SYS-1925 Lacquer Thinner or T-988 Acetone. With the screen now resting print side up we use a squeeze bottle to apply enough blockout to cover the length of the screen, applying it directly above the frame (this prevents the blockout from leaking through). Using our baby squeegee, the blockout gets scraped across the screen while being careful to smooth any ridges. Rotate the screen 90 degrees, repeat the process on all sides, and allow it to dry for 15 to 20 minutes.
Once it’s dry we add another layer of Rtape directly above and parallel to the Rtape on the opposite side. The lacquer blockout should extend slightly beyond the tape on either side. At this point there should be 5 layers: Rtape | Lacquer | Silkscreen | Lacquer | Rtape.
And that’s pretty much it! If you have any questions, or if you have any advice of your own that you’d like to share when it comes to silkscreen maintenance, let us know on our Instagram.
Be sure to check out our other posts for more deep dives into the screen printing process. Thanks for following along!
Click for Links: