With the very high contact pressure of a calender, fabrics are given a supple touch, a closed surface due to a higher material density and also a smooth, shiny finish. Calender rollers are among the most expensive components in textile machine manufacture and the slightest damage will cause defects in the textile that then reoccur in every repeat. Damage will require immediate replacement and an expensive repair. Seams can also damage the calender rollers. A seam detector detects the seam in good time and the contact pressure is reduced briefly as the seam passes through.