High-resolution, gated infrared images were taken of tin samples shock heated to just below the 505 K melting point. Sample surfaces were either polished or diamond-turned, with grain sizes ranging from about 0.05 to 10 mm. A high explosive in contact with a 2-mm-thick tin sample induced a peak sample stress of 18 GPa. Interferometer data from similarly-driven tin shots indicate that immediately after shock breakout the samples spall near the free (imaged) surface with a scab thickness of about 0.1 mm. Images were taken with gate widths of 0.2 to 0.5 μs and start times ranging from 0.3 to 1.5 μs after shock breakout. The camera and experimental techniques were described previously. [S.S. Lutz, et al., Gated IR images of shocked surfaces, in Shock Compression of Condensed Matter-2001, M.D. Furnish, ed., AIP (2002)]. Infrared radiation (3 to 5 μm) from the sample was imaged onto a gated InSb camera array with lens systems capable of resolving features on the order of 0.1 mm. Assuming a dynamic emissivity of 0.1, calculated temperatures were around 700 K for the millimeter-sized hot spots and 450 K in the surrounding area. The images showed different amounts and physical distribution of hot spots. Although there was a trend to more and higher-temperature hot spots with larger grain size, the hot spots do not appear to map directly to individual gain shapes or boundaries.