Soft and highly strain hardening metals like iron, aluminum and tantalum, often called gummy, are notoriously difficult to cut. This is due to their tendency to exhibit redundant, unsteady plastic flow with large-amplitude folding, and which results also in macro-scale defects on the cut surface and large energy dissipation. In this work, we demonstrate that this difficulty can be overcome by merely coating the initial metal surface with common adhesive chemical media like glues and inks. Using high-speed in situ imaging, we show that the media act by coupling unsteady surface plastic flow modes with interface energetics-a mechanochemical action-thereby effecting a ductileto-brittle transition, locally. Consequently, the unsteady plastic flow with folding transitions to a periodic segmentation-type flow in the presence of the surface media, with near absence of defects on the cut surface and significantly lower energy dissipation (reduction of up to 80%). This mechanochemical effect is controllable and not material specific, with the chemical media demonstrating comparable efficacy across different metal systems. This makes it quite distinct from other well-known mechanochemical effects, such as liquid metal embrittlement and stresscorrosion cracking, that are both highly material-specific and catastrophic. An analytical model incorporating local flow dynamics, stability of dislocation emission and surface media energetics is found to correctly predict the onset of the plastic flow transition. The benign nature and simplicity of the media suggests wide-ranging opportunities for improving performance of cutting and deformation processes for metals and alloys in practical settings.