A Beginner’s Guide to Exposing a Screen 

A Beginner’s Guide to Exposing a Screen

If you’re new to screen printing, one of the most crucial steps you’ll need to master is exposing your screen. This process involves transferring your design onto the screen so you can use it to print on various materials like t-shirt’s, hoodies and posters. Let’s dive into the step-by-step process to ensure you get a crisp, clear image every time.

What You’ll Need

Before you start, gather the following materials:

• Screen printing frame and mesh: Pre-stretched screens are available in different mesh counts. Choose one suitable for your design detail and ink type.
• Emulsion: A light-sensitive liquid that coats your screen.
• Emulsion coater: Used to apply emulsion evenly across the screen.
• Design transparency: A high-contrast black and white image printed on a transparent film.
• Exposure unit or light source: UV light is most effective for exposing screens.
• Exposure Calculator: To find the correct exposure times
• Emulsion remover: For cleaning the screen if you make a mistake.
• Dark room or low-light area: To apply and dry the emulsion without exposing it to light
• A block out solution/pen: to touch up any pin holes

Step-by-Step Guide

1. Prepare Your Screen and Workspace
   • Ensure your screen is clean and free of any dust or debris. We recommend cleaning with a degreaser and drying prior to coating.  A clean workspace is essential to avoid any unwanted particles getting stuck in the emulsion.
   • Work in a dark room or low-light environment to prevent premature exposure of the emulsion.
2. Coat the Screen with Emulsion
   • Pour a small amount of emulsion into your emulsion coater
   • Starting from the bottom, Tilt your emulsion coater onto your screen so the emulsion is touching the mesh. Pull your emulsion coater up gently, making sure you don’t loose contact. When at the top, tilt back and pull away from the screen.  Repeat on the other side. Note: A thin, even coat is essential for a successful exposure.
   • Allow the screen to dry in a dark place. A drying cabinet or drying rack is an ideal place to dry screens but if you don’t have access to one you can dry in a dark cupboard.  This may take several hours, so patience is key.  Make sure you dry your screen so the print side (where you put the ink) is facing upwards. This ensures any drips that form stay on he other side of the screen and do not create an un-even texture on the print side.
3. Position Your Design Transparency
   • Once the emulsion is dry, place your design transparency on the screen. The side with the ink should face the screen to ensure sharp detail transfer.
   • Secure the transparency in place with tape if necessary.
4. Expose the Screen
   • Place the screen on the exposure unit or under your light source. Ensure even contact between the transparency and the screen to avoid blurred lines.
   • Exposure time will vary depending on your light source and emulsion type. Consult your emulsion’s instructions for guidance, but typically it ranges from 1-10 minutes. We highly recommend a exposure calculator to dial in your exposure times. This can cut the experiment stage in half and put a stop to any guessing games when it comes to troubleshooting
5. Rinse the Screen
   • After exposure, rinse the screen with water to wash away the unexposed emulsion. Use a gentle spray and gradually increase the pressure if needed.
   • The exposed areas (where the light hit) will harden, while the unexposed areas (your design) will wash away, creating a stencil.
6. Dry the Screen
   • Allow the screen to dry completely before using it for printing. Ensure it’s stored in a dust-free environment.
7. Inspect Your Screen
   • Hold the screen up to the light to ensure all design areas washed out correctly. If there are any imperfections, you can use emulsion remover to clean and start again. You can also use a block out solution/pen to touch up any pin holes to save re-doing the process completely.

Tips for Success

• Test Exposure Time: Conduct a step test using an exposure calculator to dial in correct exposure times
• Emulsion Storage: Store your emulsion in a cool, dark place to extend its shelf life once mixed
• Transparency Quality: Use high-quality transparency films and inks to ensure sharp and clear design transfer.

Troubleshooting Common Issues

• Underexposure: If your design washes out entirely, increase your exposure time.
• Overexposure: If no part of your design washes out, reduce the exposure time or check for light leaks during the coating process.
• Uneven Emulsion: Ensure you’re applying a smooth, even coat of emulsion. Practice makes perfect.

Exposing a screen for screen printing may seem daunting at first, but with practice and attention to detail, you’ll be able to create crisp, professional-quality prints.