The unearthed pottery, especially that found in deserts and dry areas like Egypt, had suffered from dampness and exposure to salts. This paper presents experimental results on extraction treatments for the removal of soluble salts carried out on unearthed terracotta in Egypt. A combination of 10 times compression and 2 times immersion was used to treat the terracotta. The conductivity of leached solutions was measured, and each ion in them was analysed by ion chromatography. The conductivity of the leached solutions gradually decreased through compression. Finally, after compressing 12 times, the conductivity was less than 10µS/cm. The analysis by ion chromatography showed that each ion, including Cl-, Na+, NO3-, Ca2+, SO4²-, K+, and Mg²+, is contained in the the leached solution. This result shows that these ions were extracted from chloride and sulfate, which had precipitated in unearthed pottery. The amount of SO4 2- relative to Cl-, however, increases by immersion rather than compression. The ratios of SO4 2-/Cl-, Na+ / Cl-, K+ /Cl- and Ca2+/ Cl- in the leached solution become much higher during the immersion process than in the compress method. It follows that sulfates such as Na2SO4, K2SO4, and CaSO4 are relatively easy to dissolve from the surface and/or the inner part of unearthed pottery by the immersion method, even though these sulfates generally exhibit low solubility in water. Therefore, the immersion method is ideal for removing salts from unearthed pottery. However, it should be stressed that the combination of compression and immersion is an effective method in cases of unearthed pottery heavily damaged by salt crystallisation. Consequently, the compression method is not enough. The immersion method is necessary for the complete extraction of soluble salts.
