Plastisol vs. Water-Based Ink for Screen Printing Machines
Learn the differences between the two main types of ink used in screen printing.
There are two main types of ink used in screen printing machines: plastisol ink and water-based ink. Water-based ink consists of a mixture of water with dye or pigment. The water acts as a solvent that keeps the pigment or dye in liquid form. Plastisol ink is a PVC-based ink that doesn’t contain any solvent. You must heat the printed ink film to a temperature that’s high enough to cause the PVC resin and plasticizer molecules to cross-link and solidify. Both plastisol and water-based inks are popular, but each type of ink has its pros and cons.
Pros and Cons of Water-Based Ink
Water-based ink is a type of specialty ink for screen printing. One of the most important qualities of water-based ink is that it seeps into the fabric of the material being printed on instead of just hardening over the top of it. Water-based ink is ideal for high-speed, roll-to-roll yardage printing. It has a semi-transparent look that is great for creating a vintage appearance. Water-based ink also has a soft hand, so you cannot feel the ink film when you pass your hand across the surface of the fabric. In addition, water-based ink is more breathable and better for the environment.
One of the primary disadvantages of water-based ink is that it dries very quickly. If water-based ink is left in open mesh for even a short period of time, it can clog it and ruin the screen. Water-based inks are thinner than plastisol inks, so they may require the use of a high mesh count in order to achieve optimum results. Water-based ink is also more difficult to cure than plastisol ink. The dryers needed to remove the water from the ink are larger than those needed to cure plastisol. Furthermore, the cure temperature for water-based ink must be maintained until the water is removed whereas the ink film in plastisol only has to reach the cure temperature for a brief moment. Although some water-based ink will air dry, it is only acceptable for craft-level printing because it requires so much space for curing. Other disadvantages of water-based ink are that it is more expensive and time-consuming to work with. Moreover, water-based ink doesn’t work well on dark garments. Layering different colors of water-based ink can also be problematic because you can see through the layers.
Although you can wash screens, squeegees, and other tools with water to clean up water-based ink, you cannot just discharge the wastewater into the sewer. Using a screen cleaning system that captures solids is recommended. Catalyzed ink should be disposed of as hazardous waste unless you can dry it out before discarding it. Water-based ink that has not been catalyzed can be reused.
Pros and Cons of Plastisol Ink
Plastisol ink offers excellent coverage, color, and durability. It is easier to use than water-based ink and doesn’t clog screens like water-based ink does. Plastisol ink feels thick, heavy, and rubbery, as if it were sitting on top of the fabric. Any plastisol ink that’s left over at the end of a job can be returned to the container for reuse without any adverse effects. This can help you reduce waste. As long as the plastisol isn’t mixed with other colors or contaminated with foreign materials, there will be no difference in the ink’s quality.
Plastisol never has to be amended and screen printers can typically use it straight from the container without adjusting its strength or viscosity. Plastisol ink comes in various strengths, ranging from transparent to opaque. Opaque plastisol inks are the most expensive since they contain more pigment. The biggest drawback of plastisol ink is that it needs to be cured in an oven or at least flash cured. Furthermore, since plastisol is thermoplastic, it can melt if it comes into contact with anything that’s very hot. For example, ironing a plastisol print could smear the ink.
Check with local regulatory agencies when disposing of either cured or uncured plastisol ink. Plastisol in an uncured state is considered a hazardous waste in most municipalities. It is also necessary to use some type of solvent to remove plastisol ink from screens, squeegees, work surfaces, etc. Waste ink and solvent must be disposed of in an appropriate manner to minimize environmental impact. Fortunately, there are a growing number of environmentally sensitive solvents that serve as an alternative to petroleum-based solvents. Filtration and cleaning systems that minimize the amount of solids discharged into sewage systems are also available.
Ink is an extremely important product for any screen printing business. Consider factors like the application, ease of use, eco-friendliness, and cost in order to select the right ink for your needs. Whether you choose to print with plastisol ink or water-based ink, be sure to properly handle and dispose of the ink because it is a chemical compound.
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