This study examined the degradation of oil paint coatings on wood under UV light and heat, focusing on three drying oils: tung oil (TO), linseed oil (LO), and walnut oil (WO). Model coatings were prepared with malachite pigment on rubber wood, then exposed to 240 h of UV light at temperatures of 40 °C, 50 °C, and 60 °C. The results showed that tung oil (TO) was the most prone to degradation. After exposure to 60 °C, the lightness (L value) of TO decreased from 51.44 to 50.98, while LO and WO maintained higher lightness. The color differences (ΔE) for TO, LO, and WO were 3.08, 3.26, and 2.87, respectively. Gloss measurements revealed that TO had the lowest initial gloss (3.87 GU), while WO had the highest gloss value. After UV exposure, all three coatings showed a decrease in gloss to varying degrees. Fourier transform infrared spectroscopy (FTIR) analysis confirmed oxidative degradation in TO, characterized by increased hydroxyl and carbonyl bands, while LO and WO exhibited better chemical stability. Scanning electron microscopy (SEM) images revealed that the surface of TO was the roughest, while the WO surface was the smoothest. After UV exposure, the surface of TO became significantly rougher, while the WO coating showed almost no changes, maintaining better structural integrity. The results suggest that LO and WO are more resilient to UV light and thermal stress, making them more suitable for protecting wooden products.

This research investigates how the inclusion of bone glue affects the performance of traditional painted furniture ground layers, particularly under dry–wet cycling conditions. The ground layers, applied to wood substrates in seven different ratios of bone glue to gypsum powder (10%, 20%, 30%, 40%, 50%, and 60%), were tested for mass changes, dimensional stability, adhesion, and surface roughness. The results showed that higher bone glue content (especially 50% and 60%) led to improved stability, reduced mass fluctuations, and better dimensional stability. The 50% bone glue sample exhibited the best overall stability with minimal weight change (<1.6%) and reduced shrinkage. Adhesion strength increased with bone glue content, reaching 3.48 MPa at 60% bone glue. Lower bone glue content resulted in poor adhesion and visible defects such as cracking and blistering. SEM analysis confirmed that higher bone glue content enhanced bonding between the ground layer and the wood substrate.