the present invention is a method and apparatus for providing a low - cost and less complex micro - environment for treating a substrate using an impingement cryogenic or steam spray jet . a substrate and fixture is contained within an open - architecture prophylactic or cleaning cell whereupon the substrate and fixture is continuously bathed in a regenerated and re - circulating stream of filtered , inert , dry , heated and ionized atmosphere which bathes both the entire substrate and fixture . this prevents the intrusion of contaminating ambient atmospheres onto critical surfaces . the cleaning cavity is constantly regenerated and re - circulated through the cleaning cell to maintain a majority of the clean atmosphere wherein the clean cavity is pressurized slightly with a small volume of clean dry air or inert gas to prevent the intrusion of ambient atmosphere into the cleaning cell . a small exhaust duct removes the partial pressure of atmosphere from the open regions of the cleaning cavity , capturing the escaping cavity atmosphere . the exemplary spray cleaning applicator of the present invention provides a majority of the make - up atmosphere required to operate the cleaning cell . the treated surface is thus isolated and protected from the ambient atmosphere and contaminants contained therein prior to , during and following application of a treatment spray . the present invention allows for the simultaneous application of a variety of conventional surface treatment agents such as dry steam or snow to a critical surface . finally , the present invention controls and maintains the quality of the environment immediately within the vicinity of the substrate being treated , and the ambient atmosphere .