Use of bicarbonate solution on appropriate clays permits 100 percent recovery of all solid objects of any size, depending upon the mesh size of the screens. The solution is non-toxic and presents no hazard to the safety of the excavation staff. The process is relatively inexpensive and can be performed by anyone with readily available materials. It is so effective that in one instance, it has enabled us to find cultural material in a clay matrix where none was visible and where it is unlikely that any would have been found using conventional screening techniques. However, its effects on C-14 samples are not presently known, and the bicarbonate solution may not be effective in breaking down all clays.