Unlock the Power of Perfect Coating! Improving How You Coat Screens

Have you thought about how you coat your screens lately? Maybe the way you’re doing it works, but it might not be the best way. Instead of just sticking with what you know, why not try to make it even better?

In this guide, you’ll learn:

  • Why the right amount of Emulsion Over Mesh (EOM) makes better screens
  • How to coat a screen when it’s still wet
  • Common mistakes to avoid and troubleshooting tips
  • Recommended tools and resources for achieving the perfect coating
perfect coated screen emulsion line up perfect by screenprintingnow

Important Things in Screen Coating

Anyone who wants to be good at coating screens should know these things:

How fast you move when coating: This changes how much liquid you put on the screen.

The angle you hold the tool:

This changes how much liquid goes from the coater to the screen.

diagram illustrating proper coating angle by screenprintingnow

How hard you push on the coater: This makes the liquid spread evenly or not.

The shape of the coater edge:

This can change how much liquid gets on the screen.

comparing different coater edge shapes sharp and round edge by screenprintingnow

The speed you move the Coater is too fast and you collect air bubbles.

What is Emulsion Over Mesh (EOM)?

EOM is how far the emulsion layer goes past the screen’s threads. It’s usually talked about as a 12% percent of the total mesh thickness. The right EOM makes sure the ink goes through the screen well, giving clear pictures as the screen printing ink clears well the Mesh.

side by side comparison of prints with proper EOM vs. inadequate EOM by screenprintingnow

Coating When It’s Still Wet

Wet-on-wet coating is a common technique used in screen printing. The process involves applying emulsion to the screen while it’s still wet from the previous coat. However, the number of wet-on-wet coats depends on the mesh size.

For fine mesh screens, you can typically apply two coats of emulsion using the wet-on-wet method. Start on the print side and end on the squeegee side. Ensure your screen is clean and properly prepared before coating.

When coating larger or rougher mesh screens, be cautious about applying too many wet-on-wet coats, as the emulsion may start dripping later. In such cases, apply the initial coats wet-on-wet, then allow the screen to dry completely. Once dry, you can apply additional coats to build up the desired EOM (Emulsion Over Mesh).

Coater Edge and EOM:

The type of coater edge you use can significantly impact the amount of emulsion deposited on the screen. Typically, coaters have both a sharp edge and a round edge.

  • The round edge of the coater deposits more emulsion compared to the sharp edge.
  • Take note of which edge you are using during the coating process.

Creating a Coating Structure To achieve optimal results, it’s crucial to develop a coating structure for each mesh count. This involves documenting the specific coating techniques and number of coats required for each mesh size. By maintaining a record of successful coating methods, you can ensure consistent and high-quality results.

Smoothing the Print SideFor a smooth coating on the print side of the screen, consider the following technique:

  1. After the initial wet-on-wet coats, allow the screen to dry completely.
  2. Once dry, apply a final coat to the print side using the sharp edge of the coater.
  3. This helps smooth out any slight indentations that may have formed during the drying process.
  4. Remember to apply this smoothing coat only on the print side, not the squeegee side.

By following these guidelines and tailoring your coating process to each mesh count, you can achieve the desired EOM and ensure optimal print quality.

Common Mistakes and Troubleshooting

When coating screens, be aware of these common mistakes:

  • Uneven coating pressure, resulting in inconsistent EOM
  • Improper screen preparation (e.g., not degreasing or cleaning thoroughly)
  • Using the wrong type of emulsion for your application
  • Dry the Screen with the print side down!

If you encounter issues like pinholes or poor stencil adhesion, try these troubleshooting tips:

  • Ensure your screen is properly tensioned and degreased
  • Check your coating technique and ensure even pressure
  • Adjust exposure time and consider using an exposure calculator

Recommended Tools and Resources

To achieve the perfect coating, consider investing in these tools and resources:

  • High-quality coaters with sharp edges and comfortable handles
  • Durable, high-tension screens
  • Emulsion specifically formulated for your ink type and substrate
  • Exposure calculators and step wedges for dialing in exposure times
  • Educational resources, such as online courses or workshops on screen coating techniques

Check out for the Stencil Thickness Gauge

To Wrap It Up

Coating a screen might sound easy, but doing it really well can make your work look way better. By knowing all the steps, being careful, and using the right tools and techniques, you’ll always get great results.

Questions & Answer

How long should I let my coated screen dry before exposing it?

Till it has 30% Humidity, check with a Humidity Meter.

Can I coat my screen without using a scoop coater?

While a scoop coater is the most common and efficient tool for coating screens, you can use alternative methods if needed. For example, you can use a squeegee to apply the emulsion, but this may result in a less even coating and require more practice to achieve consistent results. It is not recommended!

How do I know if I've applied the right amount of emulsion to my screen?

The right amount of emulsion depends on your mesh count and the desired ink deposit. A good rule of thumb is to aim for an EOM (Emulsion Over Mesh) thickness of about 10-20% of the mesh thickness. You can use an emulsion thickness gauge to measure.

What should I do if I notice pinholes or imperfections in my dried coating?

If you notice minor imperfections or pinholes in your dried coating, you can try spot-correcting them using a small brush and a small amount of emulsion. Allow the touch-ups to dry completely before exposing the screen. For larger imperfections, it may be necessary to reclaim the screen and start the coating process again.

How often should I replace my emulsion?

The shelf life of emulsion varies depending on the manufacturer and storage conditions. Most emulsions have a shelf life of 12-18 months (some only 30 Days, check TDS) when stored properly in a cool, dark place. If you notice your emulsion becoming thick, lumpy, or discolored, it’s time to replace it with a fresh batch.

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