dcl Chinese Antique Research Department
Cleansing and Preservation of Antique Ceramics
After being buried underground for years or circulating on the markets, collectors often find grease, stains, rust or even microorganisms on antique ceramics. These high value collectibles have to be properly cleansed to regain their buoyance and splendor.
1. The best way to remove stains from underglaze-blue and red porcelains is to fully immerse them in a warm bath of mixed solutions of diluted Oxalic Acid (C2H2O4•2H2O, also called Ethanedioic Acid) and 65℃ hot water. The ratio of oxalic acid to water and length of time may vary depending on the conditions of the ceramics. Rinse with warm water and wait for them to air dry and avoid direct exposure to sunlight.
2. Cleaning break lines, cracks and chips can be difficult. Tapping a soft tissue with mild nitric acid directly on the stained areas and then rinse with warm water has been proven an effective method.
3. Antique overglaze porcelains can be cleaned in the same manner as soaking them in warm water bath and apply gentle detergents to remove surface stains.