Moiré effect

Moiré is an unwanted phenomenon that can occur when printing halftone illustrations, manifesting as blurring effects or disruptive patterns that were not present in the original design. This effect can seriously compromise the visual quality of the print, affecting the integrity of the image and its perception by the viewer.

Causes of Moiré

• Overlapping Screens: Moiré often occurs when multiple printing screens overlap at inappropriate angles, creating visual interference.
• Printing Resolution: Inadequate resolution, either too low relative to the complexity of the design, can also lead to the appearance of moiré.
• Substrate Quality: The type of paper or printing substrate used can influence how accurately the screens are reproduced, thereby contributing to moiré.

Prevention and Correction

• Adjusting Screen Angles: Changing the angles between different printing screens can reduce the risk of moiré. A 30-degree difference is often recommended to minimize interference.
• Use of Stochastic Screens: These screens, also called random or FM screens, disperse ink dots non-uniformly, reducing the risk of repetitive patterns and thus moiré.
• Optimizing Resolution: Ensuring that the print resolution is appropriate for the substrate and image complexity can prevent the appearance of this effect.
• Choosing Suitable Substrates: Using high-quality papers or printing substrates adapted to the printing technique can also help avoid moiré.

Impact of Moiré

Moiré can significantly degrade print quality by introducing unwanted visual elements that distract from the original content and can even make the information difficult to interpret. In fields where visual precision is critical, such as graphic design, photography, or publishing, avoiding moiré is essential to maintain high print quality.

Conclusion

Moiré is a technical challenge in the printing process that requires careful attention during file preparation and in selecting printing methods and materials. By understanding the causes of this phenomenon and applying best practices to prevent it, it is possible to achieve high-quality prints that remain true to the designer’s original intent.