Short communicationQuantitative study on the sealing material of 600 years ago

- Ancient sealing material of 600 years ago was analyzed in this research.
- TG and AAS were applied to get the quantitative information of the putty.
- The calculated ratio of lime and tung oil was lower than the ancient records.

Baochuanchang Shipyard was one of the major bases for shipbuilding and maintaining of Zheng He's fleet who sailed across the Indian Ocean in the early 15th century. Some ancient putty used in sealing wooden ships was found during the archaeological excavation of this site, and the analytical results by Fourier transform infrared spectrometer (FT-IR), thermogravimetry−differential scanning calorimetry (TG-DSC), thermogravimetry analysis (TG), and atomic absorption spectroscopy (AAS) were presented in this paper. Results of FT-IR suggested that the putty was well preserved, and calculation of the quantitative information provided by TG and AAS showed that the ratio of lime and tung oil was 1.4:1, which was lower than the records of ancient wooden ships. This research provides quantitative information of the ancient putty excavated from the Baochuanchang Shipyard, which would be beneficial for the study of shipbuilding technologies of Zheng He's treasure ships.