Many sandstones (89 of 127 tested) disaggregate in warm dimethyl sulfoxide (DMSO); no crushing is necessary and there is no known effect on minerals other than kaolinite. Fossils should be cleanly released from the sandstone matrix by gentle washing with water. Treatment is simple and relatively inexpensive. DMSO is not a serious chemical hazard or environmental problem (but see necessary precautions discussed later). Some sandstones disaggregate overnight; others require a month or so. It has been proven to work on some very hard, supposedly silica-cemented sandstones and on some carbonate-cemented concretions in sandstones. In general, disaggregation in DMSO appears to be associated with the presence of kaolinite (which is more abundant in non-marine depositional environments) and with the absence of deep burial or deformation. Even so, there is no way to predict the behavior of a given sandstone; susceptibility to disaggregation must be established by trial.