Exposure thresholds are measured for laser photothermal imaging materials that can be used as direct writing lithographic offset printing plates, as a function of laser pulse duration in the 30-μs to 1-ps range. The materials studied are based on direct imaging technology developed by Presstek, Inc. By shortening the pulse duration, the exposure threshold can be reduced by a factor of 26 from 0.52 J/cm² (30-μs duration) to 0.02 J/cm² (1-ps duration). Thermal conduction plays a key role in determining this nonreciprocal behavior. In layered media, thermal conduction is anisotropic and three dimensional, but in many cases simpler treatments of thermal conduction are possible. The conditions under which a one-dimensional model can be used are discussed and shown to apply here. The 1-D thermal conduction model fits the data accurately over a vast range of timescales for exposed spots with radii greater than ∼10 μm and provides insights into fundamental mechanisms. The practical implications of mating writing engines to materials with nonreciprocal behavior, where the thresholds decrease with decreasing pulse duration, are discussed