High Velocity Air Drying of Offset and Letterpress Inks.

The drying mechanism for offset and letterpress inks is a strong function of vapor pressures and mass transfer coefficients. Open flame dryers accomplish drying by raising web temperatures and solvent vapor pressures to high levels. High velocity air drying provides high mass transfer rates that produce rapid drying at lower solvent vapor pressures with lower web temperatures in less space. As a result, reduced moisture loss and higher ink gloss are inherent in high velocity air drying.