Elongation defines the length to which a fibre may be stretched before breaking. Raw silk has an elongation of 18 to 23 percent of its original length. Excess moisture increases the elongation of silk, but decreases its tenacity. Hygroscopic nature Moisture content and humidity are of critical importance to commercial silk production. Figure 4 illustrates the pattern of moisture regain where a hysteresis exists between the adsorption and desorption curves.
Desorption measures a greater regain at a given relative humidity.
For instance, given 65 percent RH, the adsorption regain value is 10 percent and the associated desorption value is 11.1 percent. Effect of light Continuous exposure to light weakens silk faster than cotton or wool. Raw silk is more resistant to light than degummed silk. It is advised that silk drapery and upholstery fabrics be protected from direct exposure to the light. Electrical properties Silk is a poor conductor of electricity and accumulates a static charge from friction.