Formation mechanism of “golden wire and iron wire” in celadons from Laohudong kiln in Hangzhou

“Golden wire and iron wire” are generally regarded as a specific term for the glaze cracks on the porcelains from the heirloom Ge kilns. The Laohudong kiln has a close relationship with the heirloom Ge kiln, and the porcelain unearthed from it also has “golden wire and iron wire”. To explore the mechanisms of their formation, the celadons unearthed from the Laohudong kiln site in Hangzhou were selected as the research object, and the celadons from the “Nanhai No. 1” shipwreck were used as the comparison sample. The morphology and phase composition of “golden wire and iron wire” were analyzed by three-dimensional video microscopy, scanning electron microscopy (SEM), X-ray energy dispersive spectrometry (EDS), and Raman spectrometry. The results show that the “golden wire and iron wire” on the glaze surface of the Laohudong kiln wares are mainly distributed inside the cracks of the glaze layer. The continuity of the “golden wire” is poor, while that of the “iron wire” is good. In some areas, the “golden wire” and “iron wire” overlap. The phase components of the “golden wire” area of the celadon from the Laohudong kiln are mainly lepidocrocite [γ-FeO(OH)], hematite (α-Fe₂O₃) and quartz (SiO₂). In contrast, those of the “iron wire” area are mainly biochar (C), pyrite (FeS₂) and quartz. The “golden wire” phase of the celadon from the “Nanhai No.1” shipwreck is mainly hematite and quartz, while the “iron wire” phase is pyrite and quartz. No biochar was detected. The “golden wire” of the celadon from the Laohudong kiln is the result of deposition of corrosion products during the burial process, and the “iron wire” belongs to the artificially controlled glaze decoration techniques. The similar “golden wire and iron wire” of the porcelain from the “Nanhai No.1” shipwreck are all deposits of corrosion products during the burial process, among which the iron deposits are significantly affected by environmental factors.