Why is silk screening and printing best with Water Based Inks?
Water based inks are the cleanest and most environmentally friendly way to screen print and decorate apparel. It also produces a softer more beautiful product.
Although Plastisol (a petroleum product) is the most popular ink used by printers, silk screening with water based inks produces superior prints because it penetrates the fabric more than the plastisol inks and creates a much softer feel, and is important where a "soft hand" is desirable. A "soft hand" is the condition where the ink film cannot easily be felt with the hand when passed across the surface of the fabric, popular in most "fashion conscious" T-shirt brands.
This affect is often used as an argument for why water-based is preferable to plastisol as plastisol has more of a “rubber-like” hand. Water based inks breathe with the garment, becoming part of the fibers as opposed to plastisol inks (a petroleum based product) which lie on top of the fabric.
Water-based ink also has the advantage of being excellent for high speed roll-to-roll yardage printing. Such printing is done on large sophisticated equipment that has very large drying (curing) capacity.
Water-based ink also is a good choice where ink penetration is desirable, such as in towel printing. Towels have a high nap fabric that must be printed in a manner where the ink penetrates or wicks through to the base fabric for adequate coverage. Water based inks that are specifically designed to wick into the fabric are excellent for this application. This type of ink wicking is not a desirable affect in most other fabric printing as it will destroy the design and registration of multiple colors.
Water based printing is also ideal for printing darker inks onto lighter colored garments and is useful for larger area prints where texture is important.
Even though we do both, we believe that silk screening with water based inks ,is the cutting edge of screen printing in America
So why doesn't every printer use water-based -inks?
For one reason, water-based ink is much more difficult to cure than plastisol. Since water-based inks contain water as an evaporative solvent, care must be taken to prevent the ink from drying in the screen during the silk screening process. If water-based ink is left in open mesh for even a short period of time, it can clog the mesh and ruin the screen; a main reason why most plastisol printers shy away from the water base ink printing technique. Practiced printers understand that when silk screening with water based ink they must always be conscious of how long a screen sits between prints to prevent the ink from “drying in”.
While modern water-based inks are less prone to this phenomenon, it is still a concern. Silk screening using water-based ink is also much more aggressive than plastisol towards the emulsion that is used to create the screen stencil. Emulsion manufacturers all make “water-resistant” emulsions that must be used for water-based printing and silk screening. If standard emulsion is used, the water-based ink will destroy the stencil by melting the emulsion is as little as a few minutes. Even when the proper emulsion is used, screen life tends to be much less with water-based printing than it is for plastisol printing.
There is a common misconception that because water can be used for cleaning screens, squeegees and tools, that the waste water can just be discharged in the sewer. However, the water-based ink is not just water. There are pigments, binders, thickeners, and sometimes, even eco-solvents in the ink residue. Screen cleaning systems that can at least capture the solids are still recommended; however the highly toxic solvents used in plastisol clean-up are not necessary with water base printing, a huge plus in the environment of the printing facility.