These can be dissolved slowly in acetone and toluene after setting. In most instances, it is necessary to consolidate earthenware sherds with a dilute solution of PVA or Acryloid B-72 in order to thoroughly strengthen their surfaces before they can be glued or repaired. This can be accomplished simply by immersing the sherds in a dilute solution of the resin. Thoroughly wet the pottery. For sturdy pottery, immerse in 10-20 percent nitric or hydrochloric acid until effervescing ceases.
Hydrochloric acid is preferable for glazed pottery.
Glazed, friable, or carbonate-tempered surfaces should be cleaned with cotton swabs or by applying concentrated acid, drop by drop. Immediately wipe off the excess acid or rinse in running water when effervescing stops. Continue the process from spot to spot or area by area. Thoroughly rinse the pottery in running water to remove excess acid. Remove iron oxide stains with 10 percent oxalic acid or 5 percent EDTA and rinse thoroughly.