The use of hydrochloric acid is well established on archaeological sites for cleaning cermaic finds, despite the assertion by many conservators that this could be detrimental to those ceramics of calcareous matrix or with calcareous inclusions. It was therefore decided to investigate both the extent of degradation possible on a variety of coarse ware types and a possible reduction in degradation by modifications in the washing procedure. A variety of coarse ware ceramic samples were manufactured in the laboratory and their absorption percent established and their visual appearance noted. These properties were checked again after treatment which consisted in water presoaking for various periods, then immersion in either 20% or 10% hydrochloric acid for five minutes followed by rinsing and airdrying. It was concluded that deterioration was due more to the forces exerted by the carbon dioxide evolved than by the acid itself. Several changes of rinsing water removed the acid better than did water running over the surfaces of the ceramics.