Uncoated ceramics are difficult to analyze because specimen charging can reduce the energy of the electron beam at the specimen. This effect may decrease the measured k-ratio to a fraction of its expected value. Thin carbon coatings are the usual solution to this problem. However, the coating procedure takes time, and the same coating thickness also must be applied to the standard. in the environmental SEM (ESEM). surface charge can be mitigated at the higher accelerating voltages normally used for x-ray microanalysis. in the ESEM, electrons are accelerated toward an electrically biased electron detector producing a cascade of electrons and ions from the imaging gas (water vapor) as part of the secondary electron imaging process. Positive ions drift toward the specimen and neutralize negative surface charge; however, the degree of neutralization is a function of a number of operating variables.