Trying to Solve Pin Holing Issues?
We’ve Got a Better Idea for Optimum Ink Coverage
15 May 2020
The flexographic printing market is more competitive than ever. That is why improvements in print quality to create a more appealing packaging for consumers has become an important competitive advantage.
A common issue with flexible packaging designs is the “pinholing” effect. It describes the uneven or incomplete ink distribution when printing a solid area, which leads to a loss of density and reduced color vibrancy. Only a continuous ink coverage is able to reflect light evenly and look appealing to consumers. This improvement in visual appearance of the packaging makes a big difference for printers and brand owners alike as it can positively influence a consumer’s purchase decision. The causes for pinholing can be numerous, such as:
- Ink dries on anilox and fails to transfer to plate
- Ink does not form an even film on the substrate
- Worn anilox
- Dirt on impression cylinder
- Insufficient pressure
To solve or prevent pinholing issues, printers can choose from a wide range of available process components; however, only the perfect combination of anilox, plate, tape, ink, and machine parameters will lead to optimal print results. The following actions can be taken to address the above-mentioned pinholing causes:
- Use more slowly evaporating solvents; decrease dryer capacity; increase press speed
- Reduce ink viscosity; increase ink film thickness; increase plate impression pressure to substrate; check pre-treatment or physical surface of substrate that it is not irregular, pitted or contaminated; check metering system; use suitable/appropriate solvent
- Examine condition of anilox roll for large land areas replace if necessary; use anilox with higher volume
- Clean impression cylinder
- Use higher impression set; use tape with harder foam or non-compressible tape; use build-up tape on back of plate (e.g. tesa® 4972) under solid areas
Along with the other factors, the right selection of plate mounting tape plays a crucial role for achieving continuous ink coverage. The foam hardness of the tape is an especially important factor in reaching the desired result of best solid ink density. A harder foam can help to achieve optimum ink coverage. However, it is important to note that the two components 1) tape and 2) printing plate always need to be considered in combination to find the best solution for minimizing pinholing effects.
To provide a solution to pinholing, we are offering our comprehensive assortment of 500 µm (20 mil) flexo plate mounting tapes with an “X-Hard” foam hardness. The technical advantages of our tesa® Softprint with X-Hard tapes are based on the firm foam formulation of our high-performance closed cell PE foam, providing excellent cushioning, high resilience, and fast recovery properties to ensure:
- A uniform ink laydown on solid areas
- High printing speeds
- Consistent print quality
Try our tesa® Softprint X-Hard tapes today to solve your pinholing issues and contact us for more information on the perfect combination of process components. We have you covered: don’t worry, just print.