*Article* **Effect of Rosin Modification on the Visual Characteristics of Round Bamboo Culm**

**Na Su 1,2, Changhua Fang 1,2 , Hui Zhou 1,2, Tong Tang 3, Shuqin Zhang 1,2, Xiaohuan Wang 4,\* and Benhua Fei 1,2,\***


**Abstract:** Rosin was used to treat round bamboo culm using the impregnation method. The quantitative color and gloss measurements combined with a qualitative eye tracking experiment were used to evaluate the effect of rosin treatment under different temperatures on the visual characteristics of the bamboo surface. Surface morphology analysis was also used to explore the mechanism of modification. The results showed that proper heating of the modified system was conducive to the formation of a continuous rosin film, which increased the gloss value. The maximum gloss value of 19.6 achieved at 50 ◦C was 122.7% higher than the gloss value of the control group. Heating decreased the brightness of the bamboo culm and changed the color from the green and yellow tones to red and blue. Additionally, at temperatures higher than 60 ◦C, the bamboo epidermal layer was damaged or shed, and stripes formed on the culm surface. The density of these stripes increased with an increase in treatment temperature. Eye movement experiment and subjective evaluation showed that high gloss would produce dazzling feeling, such as at 50 ◦C, while low gloss will appear dim, such as at 80 ◦C, while the gloss at 40 ◦C and 60 ◦C were appropriate. Additionally, the solid color surface below 60 ◦C had a large audience of about 73%, and the striped surface above 60 ◦C was preferred by 27% of the subjects.

**Keywords:** rosin modification; round bamboo culm; visual characteristics; eye tracking
