The magnetic properties and mineral composition of black burnished pottery and reddish-brown pottery with
soot unearthed from Pungnaptoseong, and restored black burnished pottery were investigated to determine the
black coloring mechanism and firing condition. Results indicate that an increase in the amount of magnetic
iron oxide (especially Fe3O4) by the thermal reduction reaction of hematite influences the development of black
color on the surface. Furthermore, for each sample, the black surface was determined to contain the highest
amount of magnetic iron oxide, followed by the black to dark gray matrix, and then the brownish matrix.
These results suggested that the ancient black burnished pottery was produced by a stronger reduction reaction
on the surface, as compared to the matrix during the firing process. Further, the pottery with a black to
dark gray matrix was produced through intense and prolonged reduction firing, compared to the pottery with
a brownish matrix.