As indicated above, a smoothly wound pack is always desirable. In these conditions, lower tension may be desirable. These radial lines result from the pressure from outer layers in the pack compressing the inner layers so that the turns develop a small kink. In severe cases, the periphery of the tape pack may lose its smooth round form and become lumpy. Several different winding tension control systems are popular.
Most tape leaving the factory is wound with constant torque.
Many recorders wind with constant tension. There is also the so-called programmed winding tension advocated by several U.S. Government agencies. In this case, the tape is wound with low tension close to the hub. Increased tension is applied midtape and then the tension reduces again as the outer diameter is approached. This special technique yields a pack with certain types of tape that survives a particular sequence of temperature and humidity cycles very well, but either constant tension or constant torque winding is perfectly satisfactory for normal applications and storage conditions.