Gas release profiles of manmade glasses produced under different manufacturing conditions show significant differences. Recently produced glasses reveal a strong influence of the melting conditions, the raw materials and the fining additives on the gas release profiles. The knowledge of these relationships also allows conclusions to be drawn with respect to the manufacturing process, the raw materials used and the fining agents of ancient glasses. Three types of Ramesside coloured glass samples, blue-green [b-g], olive [o], and pink [p] from the eastern Nile Delta, San el Hagar (Tanis), Egypt, were investigated [Archaeometry 39 (2) (1997) 355]. Significant differences between the three glasses were observed. The so-called temperature of bubbling allowed the minimum of melting temperature to be determined which is different to the temperature data of the softening point measured by Thermomechanical Analysis (TMA) [b-g] 580 degreesC, [o] 594 degreesC, [p] 608 degreesC [2]. A comparison of investigations of the Amara glass samples from a Petrie Flinders collection in Berlin should be published in another paper shortly. Furthermore, significant differences in the raw material ([g] carbonates > hydrates; [o] carbonates > hydrates; [p] hydrates > carbonates > hydrates) were observed. Additives in the glass batches were different in quantities: NaCl and sulphate much greater than [o] > [p]. Gas release profiles are suitable tools for the identification of vitreous samples of unknown origin.