Thrust (1959) is an iconic example of Adolph Gottlieb’s series of “Bursts” (1956-1974). The painting is grand in scale and consists of an aggressive thrash of black, gestural strokes beneath a crimson, haloed disc, on a white background. Gottlieb said that given the limited palette, his color choices were critical in conveying the emotional quality of his work. The appearance of Thrust was compromised when efflorescence became visible on the surface in 1981; the material presented as a subtle white haze that made the black appear gray. By 1996, the effect had become more pronounced, and the painting was taken off view. Recent curatorial interest in displaying the painting motivated an evaluation of its condition and of treatment options. This paper discusses the painting’s materials and techniques, the composition of the efflorescence as investigated by spectroscopic and chromatographic methods, and considerations given to its treatment.