A number of reagents for increasing the intensity of ferric gallotannate type writings were investigated. Suitable reagents were found to be. a) 8-hydroxyquinoline in ethanol and b) gallic acid in ethanol or acetone solutions. With completely faded writings tbe method of fluorescence quenching by ferric complexes of fluorescein and 8-hydroryquinoline was found very effective. For short-term development and photographing. hydrogen thiocyanic acid is suitable, because the colouration disappears and the document returns to the initial state on volatilization of the reagents. Other reagents were critically evaluated.