Ablation refers to the process of sacrificial loss of surface material to limit heat absorption.Ablative materials have been used ton protect structures from very high temperatures, that would melt metals and ceramics. The major applications for this type of insulation are a) internal rocket insulation b) space craft reentry heat shields c) war-head shields, and d) fire walls in aircraft. Environments are quite different in various applications and thus many types of ablative materials have been developed.