The pH value has an indirect relationship with the viscosity factor. If the pH value of the ink increases, the viscosity will decrease. Therefore, the drying time of the ink increases and you will have problems with the print quality. A pH meter is an instrument that you should always have, with it you can measure the level of acidity or alkalinity of the inks, allowing you to control and adjust its acidity or alkalinity if necessary.
It must always be kept in mind that water-based flexographic inks are complex mixtures that contain pigments, resins, solvents and additives, so the pH may vary depending on the formulation of the ink and its components. The recommended range is usually between neutral or slightly alkaline, with values between 8.5 and 9.5. Which means that flexographic inks tend to be alkaline (a solution with a pH of 7 is neutral, less than 7 indicates that the solution is acidic, a
Keeping the pH controlled is essential for the following reasons:
- Help maintain the chemical stability of the ink.
- The pH value has an indirect relationship with the viscosity factor. If the pH value of the ink increases, the viscosity of the ink will decrease.
- Influences the drying speed capacity.
- Maintains the color and appearance of printed ink.
- Prevents premature degradation of ink components.
- Extends the life of anilox and plates.
Likewise, an inadequate pH in the inks can lead to a series of problems:
- May affect ink stability.
- Produce insufficient or inconsistent coverage.
- Cause registration problems, smudging, or even ink separation.
- It can influence the interaction of the ink with the plates and the substrate. Causing repellency issues and overall print quality issues.
As simple as it may seem, checking the pH of the inks before starting a printing project puts you ahead of any eventuality, since you would make the adjustments before and not during (two totally different scenarios).
If you don’t know which one to buy, go to your ink supplier, they will surely recommend the one that best suits your process.