Abstract: A reusable indicating material for detecting leaks in sealed structures and other closed bodies comprises a fabric saturated with an indicator solution containing an acid-base indicator, a surfactant, a buffering system and a humectant. The indicator solution remains reactive when the fabric is dry to the touch and will indicate the presence of leaks in the structure being tested by changing color when a reactive gas escapes from the structure being tested. Upon removal from the tested structure the indicator material reverts to its original color and is available for subsequent tests.

Abstract: A method of and apparatus for detecting fuel leaks employing color variable indicators. The method comprises the steps of preparing and applying a water soluble non-staining indicator dye to a test surface, observing color changes indicative of hydrocarbon leaks and removing the indicator dye from the test surface. The apparatus comprises in combination means for preparing the indicator dye, means for applying the indicator dye to the test surface and means for removing the dye from the test surface. The indicator dye comprises a major portion of a dry inert mineral carrier from about 0.1 to about 5.0 weight percent of a direct dye which is non-staining on painted surfaces and which does not migrate into or penetrate polyurethane or epoxy resin base painted surfaces, and from 0.1 to about 1.0 weight percent of a surfactant.

Abstract: A method of and apparatus for detecting fuel leaks employing color variable indicators are disclosed. The method comprises the steps of preparing and applying a water soluble nonstaining indicator dye to a test surface, observing color changes indicative of hydrocarbon leaks and removing the indicator dye from the test surface. The apparatus comprises in combination means for preparing the indicator dye, means for applying the indicator dye to the test surface and means for removing the dye from the test surface. The indicator dye comprises a major portion of a dry inert mineral carrier and from about 0.1 to about 5.0 weight percent of a direct dye which is non-staining on painted surfaces and which does not migrate into or penetrate polyurethane or epoxy resin base painted surfaces.

Abstract: A method of and apparatus for detecting fuel leaks employing color variable indicators are disclosed. The method comprises the steps of preparing and applying a water soluble non-staining indicator dye to a test surface, observing color changes indicative of hydrocarbon leaks and removing the indicator dye from the test surface. The apparatus comprises in combination an apparatus for preparing the indicator dye, a spray apparatus for applying the indicator dye to the test surface and surface cleaning apparatus for removing the dye from the test surface. The indicator dye comprises a major portion of a dry inert mineral carrier and from about 0.1 to about 5.0 weight percent of a direct dye which is non-staining on painted surfaces and which does not migrate into or penetrate polyurethane or epoxy resin base painted surfaces.

Abstract: A method of and apparatus for detecting fuel leaks employing color variable indicators. The method comprises the steps of preparing and applying a water soluble non-staining indicator dye to a test surface, observing color changes indicative of hydrocarbon leaks and removing the indicator dye from the test surface. The apparatus comprises in combination means for preparing the indicator dye, means for applying the indicator dye to the test surface and means for removing the dye from the test surface. The indicator dye comprises a major portion of a dry inert mineral carrier from about 0.1 to about 5.0 weight percent of a direct dye which is non-staining on painted surfaces and which does not migrate into or penetrate polyurethane or epoxy resin base painted surfaces, and from about 0.1 to about 1.0 weight percent of a surfactant.