There are many variables that can affect a print’s quality during screen printing. Don't let a bad stencil be one of them. When talking about screen printing, undercutting refers to the reduction of the size of an image due to light traveling beneath the film positive. Check out these top five screen printing tips for troubleshooting undercutting during screen making.
1. Light Scatter or Halation
The number one problem we see that causes undercutting on a screen is light scatter, otherwise known as halation. Light scatter happens when light passes through the clear film positive on its way through the emulsion. To minimize light scatter, use dyed or tinted fabric.
2. Improper Exposure
Improper exposure can cause undercutting to occur. Use the Chromaline Exposure Calculator to determine proper exposure time and light source performance.
3. Placement of Film Positive
The emulsion of your inkjet film positive should be in contact with the print side of your screen in order to avoid undercutting.
4. Poor Contact of Film Positive to Screen
Another thing that can cause undercutting is if there is poor contact of your inkjet film positive to your screen. To avoid this, make sure the vacuum frame is in complete contact to all areas of the screen.
5. Poor Resolution of Film Positive
Your inkjet film positive must be sharp and UV dense. Use high quality vector artwork and check the ink density of your positive. When you hold it up to the light you should not be able to see any light through the black areas. You may need to adjust your printer settings in order to produce a high quality positive. Check out this video from Mick on setting up your printer and RIP.
Screen Printing Troubleshooting Guide
If you have any additional questions about issues with undercutting when making a screen for screen printing, contact the team at Chromaline Screen Print Products today. We've also put together this free Troubleshooting Guide that addresses seven common problems that screen printers face and how to troubleshoot them.