Flexible Graphite – produced from natural graphite – has a Carbon content from 90% to 99.9%. Graphite flakes are treated with acid, neutralized and dried. The flakes are then subjected to high temperature, and the water, after vaporizing, “blow- up” the flakes, which increase up to 200 times or more of their original volume. Those expanded flakes are calendared without any additive or binder, producing sheets of high flexibility and excellent thermal resistance. Gaskets made from flexible graphite show low creep values, defined as continuous plastic deformation when subjected to pressure. Therefore, there is only a small loss of bolt load, which reduces the need for retightening of the bolts.