The selection of which properties to determine in any given situation will inevitably be governed by a number of factors, including the nature and size of the questioned samples, what is known about the character of the crime scene or other comparison samples, and the availability or otherwise of analytical instrumentation, expertise, time, and budget. Some bulk properties can be determined relatively quickly with simple equipment and at low cost, but others require the use of highly sophisticated equipment that frequently involves longer time periods and significantly higher costs. Disintegration of a soil lump when it is placed in water can often be prevented by first wrapping it in cling film. Measurement of density provides a quick method of comparing lumps of rock, concrete, soil, or sediment which may appear visually and compositionally similar but which are compacted or cemented to varying degrees.