InkJet Printing Media
The first materials used for inkjet printing were photographic papers. These
resin-coated papers offered a strong bond for early inkjet topcoats allowing
relatively good definition for posters and photographic prints. Since this
was the first media developed, photo-based papers have become the best-selling
media in the industry. These topcoats are applied to just about every media
type you can think of from cheaper matte papers to backlit films, vinyls
and canvases.
Functions of the Topcoat
How well the media prints is almost entirely dependent on the quality of the topcoat applied to the substrate. How evenly the topcoat is applied, how well it adheres to the substrate, the consistency of the coating from roll to roll and how well the coatings accept ink will all determine the quality of the print.
- Base for the ink – the topcoat provides a base to which the ink can adhere. Without this coating, the inks would run, flake off or not dry.
- Regulates Drop Spread – for clear definition, the ink drop needs to maintain a certain circumference at its base. Coatings prevent the ink drop from spreading and flattening.
- Controls drop height – the height of the ink drop is an important factor to optimise image definition. The coating controls the height and shape of the ink droplet through controlling its spread.
- Optimises drop saturation level – the coating controls how far the ink drop saturates into the media. With some substrates, the ink drop only has the coating to adhere to because of the non-porous base substrate. The coating ensures that the ink saturates only to a certain point.
- Prevents Bleed-Through – without a coating, many media such as papers would experience bleed-through. The coating prevents ink from saturating these products and soaking through to the opposite side.
- Controls dry-time – the coating interacts with the chemistry of the ink and will affect how quickly the ink drop will dry.
- Improves image definition – a smooth, quality coating that controls saturation, bleed-through, spread and height of the drop will result in good image definition and image clarity.