December 11, 2019 | Zack Chen

The working temperature & humidity has a great impact on print quality. Temperature & humidity will mainly affect the ink and the substrate characteristic under operation.

First, let's look at the ink. When the working temperature is too high, the solvent in the ink will evaporate more rapidly, as result increasing the viscosity of the ink. When the viscosity of the ink becomes too high, the ink’s capability to flow will drop, affecting the transferability of the ink from the anilox to plate, and from the plate to the substrate. Ink with viscosity that is too high is more likely to create an ink blockage on the plate. Especially in plate areas with a finer screen. Therefore, when your temperature is too high you should constantly monitory the viscosity of your ink and add additional solvent to decrease the viscosity when necessary. On the other hand, low working temperature is also not desirable. The low temperature will decrease the solubility of the ink. If the temperature goes too low, the ink may start to solidify.  As result decreasing the transferability of the ink. In this case, you may need to stir the ink constantly and even provide additional heat to prevent the ink temperature from dropping too low.

Now, let’s look at the substrate. Paper is more easily affected by temperature and humidity when compared to film. When printing on paper, when the humidity of the working environment becomes too high, this will lead the paper to absorb the humidity, increasing the water percentage in the paper. As result the paper can become wrinkled, and easily disfigured. Winkled and disfigured paper will cause issues when it comes to holding the print registration. Excess water in the paper will also impact the ability of the paper to absorb ink. Overall, the drying will be slower under a humid work environment. When the humidity is too low, substrates are more likely to build up static electricity. The result of statics is debris being picked up onto the substrate during the printing operation affecting the print quality. Static Electricity in the operation can be hazardous, leading to fire hazards. In conclusion, the temperature and the humidity of the work environment cannot be too high or too low. The recommended work temperature would be between 20~30, the recommended humidity would be between 50%~70%.

Article by Zack Chen, KYMC