Thermodynamics in Paintings: A Physics-Based Review

Thermodynamic phenomena critically influence the creation, degradation, and conservation of classical oil paintings. This review synthesizes key principles - heat transfer, thermal expansion, energy conservation and entropy, phase transitions, and Arrhenius-type reaction kinetics, and examines their manifestation in traditional painting materials (pigments, binders, varnishes, supports). We discuss how temperature gradients induce mechanical stresses across stratified paint layers, leading to craquelure, delamination, and flow in thermoplastic media. Case studies illustrate (1) heat‐darkening of oil films in fire‐damaged works and its partial reversal via photobleaching, and (2) catastrophic instability of 19th-century bitumen-containing glazes that soften and creep near room temperature. We then review scientific conservation tools grounded in thermodynamics—active infrared thermography for subsurface defect detection, thermogravimetric and calorimetric analyses (TGA/DSC) for material characterization, and mechanical testing combined with finite‐element modeling to predict crack initiation under environmental cycling. Finally, we explore preventive strategies informed by thermodynamic modeling, from climate‐controlled display environments and microclimate vitrines to optimized backing and framing systems. By framing paintings as dynamic thermodynamic systems, this review underscores the necessity of physics‐based approaches for understanding material behavior and guiding effective preservation of our pictorial heritage.