Differential scanning calorimetry, thermogravimetry, biochemical tests, morphological investigations, via electron, polarizing and phase contrast microscopy have been used to validate the effects of a restoration method for fire injured ancient parchment codices, requiring parchment softening, regeneration, stretching and drying. The results allowed understanding of modifications induced by the heat, namely collagen denaturation, and those by the restoring process on heat damaged ancient parchments.