How to Choose Label Printing Inks: Nine Factors That Drive Print Quality and Cost

When choosing label printing inks, converters and brand owners should evaluate substrate type, printing method and conditions, special customer requirements, post-press finishing, label application and use conditions, and cost as a connected set of factors rather than a single specification.

Customer requirements often set the ink direction. If a label needs an ice-flower, frosted or anti-counterfeiting effect, the decision should start from the ink system and how it can meet both the customer's goal and the product's needs.

It is also important to ask whether the label will go through special processing with the product it is applied to. In some production flows, labels may face high temperatures or chemical reagents. The ink must then deliver strong heat and chemical resistance; otherwise, the label can deform or be damaged.

Label application and use environment are equally important. Daily chemical detergent labels usually call for inks with good acid, alkali and grease resistance. Outdoor labels must withstand wind, sunlight and rain, so light, water, high-temperature, acid and alkali resistance should be prioritized.

Cost is another key factor. Since businesses aim to maximize profit, cost must be calculated. Generally, UV label printing inks are the most expensive, water-based label printing inks come next, and solvent-based label printing inks are the least expensive. Transportation and storage costs should also be considered. Ink performance indicators include hue, fineness, saturation, gloss, adhesion, viscosity and drying property, all of which can strongly affect the printing process and print quality.

The type and properties of the substrate are among the most important determinants of ink choice. Different substrates require different inks. For example, paper labels can be printed with water-based inks, while film labels usually require solvent-based inks. Even within the same substrate category, different varieties, grades or surface properties may call for different inks.

Printing method and printing conditions also shape ink selection. Inks designed for different printing methods generally cannot be substituted for one another or mixed. Printing speed, equipment type and equipment performance can also influence the choice.

Stable viscosity is one prerequisite for consistent print quality. Viscosity that is too high or too low is not good for printing, so viscosity control matters. During printing, water and solvent evaporate continuously, causing viscosity to rise gradually. The ink viscosity should be measured frequently, changes should be recorded, and adjustments should be made promptly.

Ink drying behavior has a major effect on label printing. If drying is too fast, the pattern may become lighter or even dry on the plate. If drying is too slow, ink set-off or dirty prints can occur. In general, drying speed should match printing speed, the equipment's drying capacity and the printed pattern area.

For water-based label printing inks, pH control is highly important, with 8 to 9 generally considered suitable. A pH change in water-based ink can also change viscosity, so an appropriate amount of pH stabilizer should be added to the ink at regular intervals during printing.

Source reference: China Packaging Network (pack.cn); original link: http://news.pack.cn/show-362117.html