Research On The Softening Of Painted Armour Excavated From The Tomb Of The Warring States Time Located In Bailuzhou,Anhui Province

China is the country of origin of lacquer trees.Chinese ancestors began to harvest and use raw lacquer since the Neolithic period.In the long process of development,they continuously improved the lacquer production technology,creating a brilliant lacquer culture.A set of lacquered armor pieces unearthed from the Warring States tomb M585 in Bai Lu Zhou,Lu'an City of Anhui Province were in good conditions,with considerable numbers,beautifully produced,and of high historical,scientific and artistic values.These relics not only provide valuable physical information for the study of military,technology and culture at that period,but also help to identify the occupant of the tomb.However,deteriorations such as embrittlement,fracture and deformation exist in these lacquered armor pieces and they need protection and repair.Softening technology of the lacquer paint is the key of protection.In precedent studies,the choice of softening conditions of lacquer paint,such as softening solution concentration,softening temperature,softening duration,etc.,mainly rely on experience,without scientific screenings.Especially for the softening mechanism of the lacquer paint,predecessors only made comparison research on the structures of lacquer pieces before and after softening,without analyzing the softening process.This paper mainly carries on the following work:(1)the conditions and deteriorations of these lacquered armor pieces were analyzed;(2)through ultra depth of field microscopy,scanning electron microscopy and infrared spectroscopy,production materials and process of unearthed lacquered armor pieces were analyzed,which provides the basis for the study of protection and repair work and the softening mechanism;(3)through scientific screening on the softening conditions of the lacquered armor pieces in the process of experiment,the optimal conditions for the softening was obtained;and(4)through ultra depth of field microscopy,infrared spectroscopy and thermogravimetric analysis,lacquered armor pieces with different softening duration were examined and the softening mechanism of the lacquer paint was studied.Through the above researches,the best softening condition was found out:with 70%1,2-propylene glycol,softening temperature at 100? and softening duration of 24 hours.Meanwhile,the microscopic mechanism of lacquer paint softening was obtained:during the softening process,physical and chemical dissolved swellings occur in lacquer paint.In the process of physical dissolved swelling,1,2-propylene glycol fills the gap between the macromolecules of the lacquer paint,which increases the distance between the macromolecules,reduces the intermolecular force and the hydrogen bonding force,resulting in the decrease of the internal stress of the lacquer paint.While during chemical dissolved swelling,the internal molecular chain of the lacquer paint breaks and reduces the integrity of its structure,resulting in the decrease of the internal stress of the lacquer paint,and therefore the softening effect is achieved.