Screen Printing - June/July 2012 - (Page 32)

Direct-to-Garment Site Preparation and the Environment This article points out the importance of humidity and temperature control when using DTG printers. Paul Borucki Kornit irect-to-garment (DTG) printing can be integral part of a garment decorator’s production process when operators maintain necessary environmental conditions for optimum operation. To shed some light on the delicate nature of DTG machines, each machine manufacturer can use a wide variety of printheads to apply ink to a garment. These printheads use piezo technology to deliver drops of ink measured in picoliters. A picoliter is one trillionth of a liter. The drops of ink can range from a small, 3.5-pl drop on an Epson printhead to a large (by industry standards) 85-pl drop used on the Dimatix Spectra Nova 256 printhead. This information is important as we try to understand the impact that the surrounding environment has on these minuscule droplets of ink. D What to control There are three simple, but important, issues to control in DTG operation: humidity, temperature, and airflow. As we make the change from winter to spring, everyone can feel the change in the weather from the dry and cold air of winter, when humidity can be 32 screenprinting near zero, to the rainy months of spring when humidity can be almost 100%. These abrupt climatic changes directly impact the printing ability of DTG machines. Controlling the environment starts with intelligent planning as to where the equipment should be placed within a printing operation (Figure 1). Consistency in the environment is key when finding the best location for the machinery. This is especially important in multi-shift operations, where conditions can change to extremes from noonday direct sun to no sun late at night. Wide variations of conditions can explain why the machinery can operate flawlessly and then be inconsistent from one shift to the other. Many desktop models can be placed within a confined space where humidity, temperature, and airflow can be controlled. Larger models may need to be situated in a much more substantial manufacturing area, where conditions are difficult to control. When placing a smaller DTG machine, even in an office-type environment, you still must be aware of simple issues that can cause changes in the environment. Beware of the open door. If a door is left open, the air moving across the printheads can lead to ink drying on and in the printheads. This is especially important in an industrial situation where large overhead doors sometimes remain open. This will eliminate any control over the environment and ultimately result in poor print quality. Many people assume that the area is being controlled already, but open doors, open windows, heaters, and fans are all culprits in causing conditions that can harm a DTG machine. A machine placed by a door that is being opened and closed throughout the day will change the temperature and level of humidity near the machine by allowing the moist air to escape and then slowly change back to your desired humidity range settings as the humidifiers work to add moisture to the air. Unless the machines are kept in a controlled atmosphere with limited access, where the humidity is no less than 40% and up to as high as 80%, the dry surrounding air can cause the ink to dry inside the piezo printhead, causing it to plug, resulting in streaks in the printed image. In the worst case

Table of Contents for the Digital Edition of Screen Printing - June/July 2012

Screen Printing - June/july 2012
Contents
Newsworthy
New Products
Digital vs. Screen and the Dilemma of Process Improvement
Grayscale Magic
Step Up Your Game With Team Wear
Boosting Garment-Printing Efficiency
What Printers Think About Rip Software
Direct-to-Garment Site Preparation and the Environment
Industry Update
Shop Talk
Classifieds
Distributor/Dealer Directory
Ad Index
Editorial Insights

Screen Printing - June/July 2012