A Beginner’s Guide to Exposing a Screen 

A Beginner’s Guide to Exposing a Screen for Screen Printing

If you’re just getting started with screen printing, learning how to expose your screen is one of the most important steps. This process transfers your design onto the screen, which you’ll then use to print on things like t-shirts, hoodies, or posters. Follow this step-by-step guide to help you get clean, crisp results every time

What You’ll Need

Before you start, gather the following materials:

• Screen printing frame with mesh – Choose a mesh count based on the detail of your design and the type of ink you’re using.

• Photo emulsion – A light-sensitive liquid that coats your screen and reacts to UV light.

• Emulsion coater – Helps you apply the emulsion in a thin, even layer.

• Design transparency – A high-contrast black image printed on transparent film.

• Exposure unit or UV light source – For curing the emulsion with your design.

• Exposure calculator – Optional but highly recommended to find the right exposure time.

• Emulsion remover – Used if you need to clean and redo the screen.

• Dark or low-light room – Essential for handling emulsion without exposing it too soon.

• Block-out pen or solution – For touching up any pinholes or small mistakes.

Step-by-Step: How to Expose a Screen

1. Prepare Your Screen and Workspace

Make sure your screen is clean and free from dust or grease. Use a degreaser and let it dry completely. Work in a dark or dimly lit room to avoid premature exposure of the emulsion.

2. Coat the Screen with Emulsion

• Pour a small amount of emulsion into your coater.

• Tilt the coater against the screen so the emulsion touches the mesh, then slowly pull it upward.

• Maintain smooth, even pressure and avoid losing contact with the screen.

• Repeat on the reverse side for even coverage.

• Leave the screen to dry in a dark, dust-free space. A drying cabinet is ideal, but a cupboard can work too.

• Make sure the screen is angled so the print side (the side you’ll be applying ink to) is facing up. This helps prevent drips from creating texture on the printing surface.

3. Place Your Design Transparency

Once the emulsion is fully dry, lay your design on the screen with the ink side facing down (toward the screen mesh). Use tape if needed to keep it in place.

4. Expose the Screen

• Position your screen under your exposure unit or UV light.

• Ensure the transparency is in firm contact with the screen to avoid fuzzy edges.

• Exposure time depends on your light source and emulsion brand – it can range from 1 to 10 minutes. Always check the instructions.

• Using an exposure calculator is a great way to find the perfect timing and eliminate guesswork.

5. Wash Out the Image

After exposure, rinse the screen gently with water.
The hardened (exposed) areas will stay in place, while the unexposed areas – your design – will wash away, forming your stencil. Increase water pressure if needed, but go gently at first.

6. Let It Dry

Once your image has washed out clearly, allow the screen to dry completely in a clean, dust-free area.

7. Inspect and Touch Up

Hold the screen up to a light to check your design.
If parts didn’t wash out properly, you might need to use emulsion remover and start again.
Small pinholes or gaps can be patched with a block-out pen or solution to avoid redoing the entire screen.

Extra Tips for Success

• Test Your Exposure Time: A step wedge test using an exposure calculator helps you fine-tune your timing.

• Store Emulsion Properly: Keep it in a cool, dark place to extend its shelf life.

• Use High-Quality Transparencies: For sharp, clean transfers, invest in good transparency film and strong black ink.

Troubleshooting

• Underexposed Screen: If your design washes out completely, your exposure time was too short.

• Overexposed Screen: If no part of the design washes out, the screen was likely exposed for too long or had light leaks during coating.

• Uneven Coating: Practice applying a thin, even layer of emulsion. It makes a big difference in your final print.

Final Thoughts

Exposing a screen might feel tricky at first, but it gets easier with practice. By following the right steps and keeping your workspace clean and light-safe, you’ll soon be making high-quality prints with confidence.