Controlling the Variables that Affect Your Screen Printing Ink Deposit
How much ink you lay down on your screen prints will depend on your individual print job and your substrate. Too much ink on your substrate can lead to prints that bleed beyond the stencil edge, soak through the substrate or fail to cure completely. Too little ink can make the print too light, affect color matching or lead to problems with fibrillation. Knowing how to troubleshoot problems with ink deposits that are too heavy or too light can help you lay down the right amount of ink every time. When it comes to screen printing, there are a few elements that affect how heavy or light your ink deposit is.
Perhaps more than anything else, your screen will affect how much ink is deposited on to your screen print — the lower the mesh count, the wider the openings in the screen and the heavier the ink deposit. Most screen prints are made with screen mesh counts between 110 to 160; if you are laying down a typical screen print with regular ink, you can go up or down in mesh count within this range to adjust the amount of ink flowing through the screen during printing. Mesh counts between 180 and 200 are used for more detailed prints; mesh counts between 230 and 280 are used for a softer hand feel but may affect your print’s color due to the low level of ink that passes through the screen. The lower mesh counts are used for making heat transfers, specialty inks with large particles or heavy athletic prints.
Be aware that mesh count isn’t the only aspect of the screen that will affect the print; the thickness of the screen thread also will impact your screen print. If your ink flow doesn’t fit with what’s expected from the mesh count of your screen, you might want to review the diameter of the thread. A thicker thread will reduce the size of the screen opening and lead to a lower ink deposit, while a finer thread will have the opposite effect.
For more information on choosing the right mesh count for your screen printing job, check out this blog: Screen Printing 101: Choosing the Right Mesh Count
The viscosity of your ink will affect how easily ink passes through the screen and how heavily it deposits on your substrate. If ink is bleeding beyond the edges of your screen printing stencil, the ink likely has been thinned too much for your print job. If the ink deposit is too light, by contrast, you might need to add a reducer to allow the ink to flow more easily during the screen printing process.
The firmness of your squeegee also has an impact on the weight of your screen printing ink deposit. A harder squeegee will pass over the screen more lightly and allow the screen to spring back away from the print, sheering away with a lighter ink deposit. A softer squeegee, on the other hand, pushes more ink through the screen during printing. You also might want to assess the angle of the squeegee during printing. Angling the squeegee toward the print in the direction of your print motion will increase your ink deposit, while a higher angle will reduce it. A 45-degree squeegee angle is a good, neutral starting point for printing.
Also check out: Choosing the Right Squeegees for Your Screen Printing Jobs
Your stencil serves as a reservoir for your ink during screen printing. If the stencil is too thin, your ink deposit similarly will be too light. Most importantly, for an adequate ink deposit during screen printing, your stencil needs to be thick enough on the print side of the screen, or the side of the screen that touches your substrate. To ensure that the stencil is thick enough, consider coating both sides of the screen with emulsion once, then adding an additional coat of emulsion on the print side of the screen. Dry your emulsion with the screen in a horizontal position, with the print side of the screen down.
For more on preparing sharp stencils for your screen prints, read: Preparing Your Screens the Right Way: Screen Printing Emulsion Techniques and Timing
Screen printing technique
If you are printing on a manual screen printing press, your screen printing technique will have an impact on how heavy of an ink deposit you lay down. Too much pressure on your squeegee can lead to a heavy ink deposit that bleeds beyond the edges of your stencil or leaks through the layers of your substrate. Too light of a stroke can mean a less opaque deposit that leaves the color of your substrate visible during printing. You also want to be sure to flood your screen before printing. First, drag the squeegee over the screen just to fill the stencil with ink. Then, use a heavier squeegee stroke to lay the print down onto the screen. This technique will ensure that you are getting a full ink deposit on your substrate with every print.
An ink deposit that’s too heavy or too light can ruin an otherwise great screen print. Your screen printing equipment, supplies and technique all play a role in determining how much ink ends up on your substrate. If your ink deposit isn’t quite right for your print job, evaluate the different variables that affect your ink deposit. Knowing how to troubleshoot problems with ink deposits can save you from frustration during screen printing and ensure you deliver quality prints to your customers every time.