A Look at the Myths and Realities Surrounding Solvent
By Tony Martin, president, Lyson Inc.
The recent introduction of lower-cost solvent, wide-format printershas opened up the market for inkjet printing in outdoor applications. These systems are selling in increasing numbers and many new machine and ink vendors are appearing on the scene. However, popularitydoesn’t equate to understanding the features and benefits of the many different inks available.
Webster’s New World College Dictionary defines solvent as "a substance, usually aliquid, which dissolves another substance." This can describe any liquid – including water. But in the inkjet world, the term is used to describe any ink that is not water-based. On top of this, theterms the industry uses to describe inks include soft, mild, safe and green, as well as hard, real, true and strong. No wonder people are confused.
One of the more intriguing terms used iseco-solvent ink. To most people, "eco" means ecological. But these inks generally contain glycol esters or glycol ether esters – both derived from mineral oil – hardly a renewable resource or an ecologicallysound process. Perhaps the terms mild and aggressive might best be suited to describe the two groups that include solvent inks.
To Work, It Has To Stick
The vast majority of images for outdoordisplay are printed on nonabsorbent, uncoated materials, such as self-adhesive vinyl and scrim banner. The resulting print has to be weatherproof, fade-proof and largely scratch-resistant. In order tomeet these performance criteria, the inks use a colorant in the form of a pigment – a very fine powder – and as the media is nonabsorbent, a resin or glue literally is used to stick the pigment ontothe surface.
The solvent is really a carrier fluid to keep the ink in liquid form for jetting, and once the ink has been applied, the solvent evaporates. Most printers use forced drying in the...