Prepping a screen for water-based inks can be a little more tricky than plastisol. The print deposit is thinner, the ink dries on the screen over time, and the ink can potentially break down emulsion faster than plastisol ink would. Because of this, you need a good screen to get a good print. Let’s go through the process of making a screen so you’re prepared for your next water-based job.
Photo by Salt & Pine Co.
CHOOSING THE RIGHT MESH
One of the first steps to prepare a screen for water based printing is to choose the right screen mesh for your ink. Since water-based inks are thinner than plastisol inks, you will need to choose a slightly higher mesh count to prevent the print from getting muddy.
The lowest mesh count printers should use when prepping a screen for water-based printing is 156. If you use a screen with mesh count under 156, you run the risk of depositing too much ink on the shirt. This will cause oversaturation, which messes up your print and leads to issues when curing the ink.
Base your mesh count decision on your image detail and coverage area of your print. The larger the area and the less detail present in your design, the lower the mesh count. The higher the detail and smaller the coverage, the higher you can go in the mesh count.
There are a couple more things to consider when choosing the right mesh count. If you are printing on a lighter garment with darker ink colors, try a higher mesh count. Make sure you get enough ink coverage when you pull your squeegee. If you’re printing on a darker garment with light ink colors, lowering your mesh counts can help to get the coverage you need.
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PICKING PROPER EMULSION
When printing with water-based inks, it’s important to choose a water-resistant emulsion to coat your screen. Some emulsions are more water resistant than others. Using a water-resistant emulsion like Baselayr Long Lasting or Baselayr Complete will help you to avoid premature emulsion breakdown. For long runs, you can take some extra steps to ensure your emulsion doesn’t break down during production (more on this later).
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PROPER SCREEN PREP
Prepping a screen for production can be a challenge until you get everything dialed in. Here are a few tips to prepping a screen perfectly every time.
DEGREASING
Don’t skip degreasing. Whether your screen is fresh out of the box or you’ve reclaimed it more times than you can remember, you gotta clean it. If possible, use water that is as close to PH neutral as possible. Make sure you don’t use hard or soft water, as mineral deposits left over on the mesh will wreak havoc with your emulsion durability. Using a degreaser will remove any oils, dust, and dirt from the mesh, all of which can cause issues in the adhesion of your emulsion (like pinholes and fish eyes). Emulsion prep also promotes better adhesion to the mesh, which will help you get a stronger, more durable stencil for water-based print runs.
These issues are especially concerning when printing with water-based inks, since the emulsion is prone to faster breakdown. Starting with a properly degreased screen will help your stencil last longer.
Before you move on to coating screens, make sure the screen is completely dry. This will give the emulsion the best chance for adhering properly to the screen.
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COATING SCREENS
When coating a screen for water-based printing, create as thin of a stencil as possible. A 1x1—or at most a 2x1—coat is best for coating screens for water-based printing. Remember that the thicker the emulsion coat gets, the harder it is to resolve detail. It will also be more difficult to properly expose the screen. An improperly exposed screen is prone to early emulsion breakdown. Always test your screens before heading to production.
PRO TIP: It’s easy to create a thicker coat of emulsion with thin thread mesh. Pull back a little when coating the screen. Tilt the scoop coater back a bit to maintain a thinner coating.
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EXPOSING YOUR SCREEN
Once your screens are coated and dry, it’s time to expose them. Exposure times vary depending on your emulsion thickness, mesh and thread counts, standard vs. thin thread mesh, and your light source. These factors will also affect the amount of detail you can keep on a screen.
Use a 21-step grayscale calculator to dial in your exposure times. Once you rinse out the screen, you'll have a better idea of how long you should expose.
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POST-HARDENING AND POST-EXPOSING
Once your screen has been exposed, you have the option to take an additional step of hardening the stencil through post-hardening or post-exposure. You can do this a couple of ways.
POST-EXPOSURE
Place the screen back on the exposure unit and expose it again. The post-exposure process will help to harden any remaining soft emulsion. Post-expose after you have already washed and dried out the image.
POST-HARDENING
You can chemically harden a stencil with products like Baselayr Emulsion Hardener. Apply the hardener thinly and evenly to both sides of an exposed, dry screen. A sponge, sponge brush, brush, or cloth will work to apply the emulsion hardener. Wipe up any excess hardener. If it’s applied heavily and left in the image area, a slight film may appear. Remove the excess to minimize potential on-press issues.
Leave the screen alone for a couple hours to allow the hardener to penetrate the emulsion.
Let the screen “cure” or crosslink overnight for best results. If you need to use the screen immediately, place it in a high heated box (above 120°F) for 1-2 hours. If you use the screen before the hardener has fully penetrated and chemically changed the emulsion, the screen will have better durability but its effectiveness will be reduced.
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Whether you post-harden or post-expose your screen, both of these steps make it more difficult to wash out the stencil during the reclaiming process. It’s a small price to pay to prevent your screen from prematurely breaking down during the printing process.
Photo by Symmetree Clothing
Prepping your screens for water-based printing doesn’t have to be difficult. By following these steps and testing your screens to hone in your process, you’ll be able to print with water-based ink without worrying about your screen breaking down during your print run.
