EOM stands for “Emulsion Over Mesh”

EOM is typically represented as a percentage of the total thickness of the emulsion layer, including the mesh threads.

Here is a breakdown of EOM and its importance in screen printing:

• EOM and Print Quality: Having the correct EOM is essential for achieving high-quality screen prints. Too little EOM can lead to several issues, including:
  • Poor edge definition
  • Halftone dots not forming correctly
  • Ink bleeding underneath the stencil
  • The threads of the mesh coming into direct contact with the substrate, which can create an unwanted “stencil” that blocks ink.
• Recommended EOM: The recommended EOM varies depending on the type of printing being done.
  • For general printing that doesn’t require fine detail, an EOM of around 20% of the mesh thickness is typically sufficient.
  • For prints with fine detail, halftones, four-colour process printing, or UV printing, a thinner stencil with an EOM of approximately 10% is recommended.
• Factors Affecting EOM: Several factors can affect EOM, including:
  • Coating Technique: The method used to coat the screen with emulsion (e.g., wet-on-wet, face-coating) can affect the EOM.
  • Scoop coater: The fill level of the scoop coater and the pressure applied to it can change the amount of emulsion transferred to the screen. The edge of the scoop coater (rounded or sharp) can also impact the amount of emulsion deposited.
  • Emulsion Type: The type of emulsion used (e.g., dual-cure photopolymer, pure photopolymer) and its solids content can impact shrinkage and affect the final EOM.
  • Mesh Count and Thread Diameter: Different mesh counts and thread diameters have different open areas, influencing the flow and buildup of emulsion.
• Measuring EOM: Specialized tools, such as microscopes and electronic thickness gauges, are used to measure EOM. These tools help ensure the EOM is within the desired range for optimal printing results.