Precious veneer possesses exceptional decorative properties, but its inherent combustibility makes it susceptible to rapid flame spread in fire scenarios. In this study, a ternary biobased flame-retardant system comprising phytic acid (PA), cytosine (CY), and vitamin C (VC) was developed and introduced into the veneer by a one-step impregnation method. The treated veneer retained its decorative quality, exhibiting minimal color change (ΔE* = 1.86) and supporting the formation of a uniform waterborne polyurethane coating comparable to that on untreated veneer. The PA–CY–VC system significantly enhanced fire safety: it increased the high-temperature char residue to over 24%, prevented ignition in sustained flame tests, and effectively suppressed flame propagation. At the optimal CY/VC mass ratio of 1:1, the total heat release and total smoke release were reduced by 25.5% and 54.0%, respectively, compared with those of pure veneer. Mechanistic studies indicated that the system operates through a synergistic combination of condensed-phase and gas-phase actions, promoting the formation of a stable, graphitized protective char while releasing flame-inhibiting gases. This environmentally benign, biobased flame-retardant system provides a sustainable strategy for simultaneously upgrading the fire safety and preserving the aesthetic value of high-end decorative veneers, promoting their wider application in fire-sensitive settings.
Li et al. (2026) studied this question.