Preparation of Modified Beeswax and Its Influence on the Surface Properties of Compressed Poplar Wood

Beeswax was modified through the direct blending of nano-TiO2, chitosan, acid dyes, and neutral dyes. With the varied modified beeswax, hot waxing was conducted on compressed poplar wood. Treated wood surfaces were characterized with scanning electron microscopy and thermogravimetric analysis. Results show that the C, O, N, Au, S, and Ti elements in modified beeswax successfully penetrated into pits of compressed poplar wood, imparting rich colors to the wood surface. The blending of 10% (mass fraction) beeswax, 0.2% chitosan, and 0.05% neutral red was the best treatment for mulation for improving the in-surface staining uniformity, durability, surface gloss, contact angle, and texture conspicuity of compressed poplar.


Introduction
Beeswax is a widely used protective material in traditional Chinese wooden architecture and hardwood furniture. During the hot waxing of hardwoods, problems such as discoloration, poor durability, and high cost often occur. China is a country lacking valuable timber resources but is rich in fast-growing wood resources. How does one effectively use fast-growing wood resources, reduce costs, and improve the surface properties of wood? One possible solution is to treat the wood surface with hot modified beeswax.
In recent years, scholars have studied the engineering process of wax modification and traditional waxing, and factors affecting the quality of waxing [1][2][3]. Krause et al. studied the preparation process of lignite wax and improved antibacterial and anticorrosion properties of the wax on wood surfaces [4]. In the synthesis of a new environmentally friendly wax for wood, Li et al. directly mixed linseed oil, tung oil, and other natural extracts at a temperature of 130˝C and determined the optimum ratio of the wax by testing hardness, appearance, and the color of products [5]. Scholz et al.'s study indicated that amide wax imparts excellent termite resistance to wood [6]. Bonaduce used mass spectrometry and gas chromatography to describe characteristics of the beeswax in art works [7]. Donaldson studied the deformation degree of the tracheid of compressed wood and analyzed the microstructural changes in compressed wood after hot waxing with confocal fluorescence imaging and spectroscopy [8][9][10][11]. Guo conducted research on the durability of Burmese rosewood to ultraviolet light after hot waxing by nano-TiO 2 -modified hydrophobic beeswax [12]. Evans studied the effectiveness of wax and oil emulsion additives, aimed to improve the performance of preservative-treated wood [13]. Levi studied the distribution and effectiveness in Pinus sp. of a water-repellent additive for water-borne wood preservatives [14]. However, the aforementioned research did not focus on the description of the preparation process of the effect of modified beeswax and influence of hot waxing treatment on wood properties.

Experimental Methods
Preparation of modified beeswax: Beeswax was added to a 100-mL beaker and melted in a 80-˝C water bath. Chitosan, nano-TiO 2 , and dyes were added to the melted beeswax and were stirred in a high-speed FLUKO-FA25 homogenizer (10,000 r/min) at a speed of 10,000 r/min for 1 h to achieve uniform dispersion of chitosan, nano-TiO 2 , and dye particles in the beeswax.
Hot waxing of poplar wood specimen with modified beeswax: The waxing level was 50 g/m 2 , the wax stripping time was 6 minutes, and a baking temperature of 90˝C was used. The melted modified beeswax was dotted with a brush on the buffed compressed wood surface. Then, the wood surface was baked at 150-250˝C with a hot air gun (LEISTER, Kaegiswil, Switzerland) thermal spray for 3 min, followed by low-temperature baking for 30 s to promote the penetration of beeswax in wood pores. After solidification of beeswax, the floating (poorly absorbed) wax was removed from the wood surface using a special shovel and subsequently wiped with a clean cotton cloth.
Modified beeswax's heat resistance test: For the waxed wood specimens A1, A2, A3, B1, B2, and B3 TGA analysis, the measurement range was from room temperature to 500˝C, with a heating rate of 10˝C/min in air. The mass of each sample was 5 mg. Using the thermal decomposition curve of modified beeswax, we compared the thermal stability of six modified materials.
Permeability test: The waxed wood specimens A1, A2, A3, B1, B2, and B3 were cut with a blade into 5 mmˆ5 mmˆ1 mm specimens, and in this process the cutting edge of the blades was only used once. A scanning electron microscope was used to analyze the microstructure of six kinds of modified beeswax on the surface of compressed poplar wood.
Chromaticity detection: For the waxed wood specimens A1, A2, A3, B1, B2, and B3, an aging test was conducted respectively for 60 h in total using a XXL+ xenon lamp aging chamber. Wood color changes were quantified by the standard colorimetric parameters (brightness L*, red-green chromaticity index a*, yellow-blue chromaticity index b*) recommended by the International Commission on Illumination (CIE). Using a handheld spectrophotometer, those designated test surfaces were detected every 12 h. In addition, we calculated the change of each color parameter before and after UV radiation, i.e. ∆L* (brightness difference), ∆a* (red-green chromaticity difference), and ∆E* (color value). Three points were taken for the test surface of each specimen, and the average of these three points was calculated to represent the wood color of specimens. The calculation Equation (1) is as follows: Detection of surface hydrophobicity: A video-based optical contact angle measuring system OCA 20 was used to measure the advancing contact angle of the surface of A1, A2, A3, B1, B2, and B3 specimens at different aging stages [16]. The liquid used was distilled water, and the volume of the measuring droplet was 5 µL. The final result was the average from three different positions randomly selected for each specimen.
Detection of surface gloss: A KGZ-IB portable gloss meter (Tianjin Keqi High and New Technology Corporation, Tianjin, China) was used to measure the surface gloss of A1, A2, A3, B1, B2, and B3 specimens, with three detecting points for each specimen. To ensure data accuracy, the mirror gloss meter was calibrated with the value of 25.5˝, calibration was performed after the detection on each point. Gloss values are the average of three detecting points.
Test of surface texture features: Wood surface of A1, A2, A3, B1, B2, and B3 specimens were scanned respectively with (LA2800) a scanner at different aging stages. The obtained images were subject to multi-layer decomposition using MATLAB texture program and wavelet analysis to extract surface texture features. The abbreviation LL represents the low-frequency component in orthogonal wavelet decomposition, and LH, HL, and HH represent the high-frequency component of the horizontal edge, vertical edge, and diagonal edge, respectively. Figure 1 shows the thermogravimetric (TG) curves of pure beeswax and six kinds of modified beeswax. It can be seen that with the increase of temperature, there was major degradation of both pure and modified beeswax. Pure beeswax degraded and lost weight mainly in the range of 155.9-465.2˝C. The B3 = beeswax + neutral red + chitosan, range was widened through the addition of chitosan to 168.9˝C-477.3˝C. The initial degradation temperature and the maximum weight-losing temperature increased from 155.9˝C and 465.2˝C of the pure beeswax to 168.9˝C and 477.3˝C, respectively. The graph shows that the inclusion of chitosan improved the thermal stability of the beeswax. It can be seen from the TG curves that, after thermal degradation, the chitosan-modified beeswax had more residues than the pure wax control. Analysis revealed that the main components of the pure beeswax are esters, free acids, free alcohols, and hydrocarbons, and the residue after pyrolysis was about 0.3% of its original weight. The B3 (beeswax + neutral red + chitosan) ratio was raised to 2.15% after the modification through chitosan [17]. (c) A3 = beeswax + acid red + chitosan; (d) B1 = beeswax + neutral red; (e) B2 = beeswax + neutral red + nano-TiO2; (f) B3 = beeswax + neutral red + chitosan.

Surface Energy Spectrum of Modified Beeswax-Treated Compressed Poplar Wood
In Figure 2, C, O, N, Au, and S elements can be seen clearly in Figure 2a (beeswax + acid red) and 3a (beeswax + acid red + chitosan). Besides these five elements, Ti can also be seen in Figure 2b (beeswax + acid red + nano-TiO2). As for Figure 2d (beeswax + neutral red) and Figure 2f (beeswax + neutral red + chitosan), C, O, N, and Au can be clearly seen, and from Figure 2e (beeswax + neutral red + nano-TiO2) we observed five elements: C, O, N, Au, and Ti. Therein, C mainly came from the wood; Au came from the coating process during the sample preparation for electron microscopy; O partly originated from the wood itself and partly from the hot waxing; N came partly from chitosan and partly from acidic red and neutral red dyes; S was absorbed from the acid red dye; and Ti was derived from the nano-TiO2 added for modification and can be observed in the thin wax layer. This suggests that hot waxing treatment successfully attached acid red, neutral red, nano-TiO2, and chitosan to the wood surface [18]. (c) A3 = beeswax + acid red + chitosan; (d) B1 = beeswax + neutral red; (e) B2 = beeswax + neutral red + nano-TiO 2 ; (f) B3 = beeswax + neutral red + chitosan.

Surface Energy Spectrum of Modified Beeswax-Treated Compressed Poplar Wood
In Figure 2, C, O, N, Au, and S elements can be seen clearly in Figure 2a (beeswax + acid red) and 3a (beeswax + acid red + chitosan). Besides these five elements, Ti can also be seen in Figure 2b (beeswax + acid red + nano-TiO 2 ). As for Figure 2d (beeswax + neutral red) and Figure 2f (beeswax + neutral red + chitosan), C, O, N, and Au can be clearly seen, and from Figure 2e (beeswax + neutral red + nano-TiO 2 ) we observed five elements: C, O, N, Au, and Ti. Therein, C mainly came from the wood; Au came from the coating process during the sample preparation for electron microscopy; O partly originated from the wood itself and partly from the hot waxing; N came partly from chitosan and partly from acidic red and neutral red dyes; S was absorbed from the acid red dye; and Ti was derived from the nano-TiO 2 added for modification and can be observed in the thin wax layer. This suggests that hot waxing treatment successfully attached acid red, neutral red, nano-TiO 2 , and chitosan to the wood surface [18].

Permeability of Modified Beeswax on the Surface of Compressed Poplar Wood
In Figure 3, it can be clearly seen that samples A1 = beeswax + acid red, A3 = beeswax + acid red + chitosan, B1 = beeswax + neutral red, B2 = beeswax + neutral red + nano-TiO2, and B3 = beeswax + neutral red + chitosan, have pits on the radial section of compressed poplar wood that are filled with modified beeswax. This indicates that hot waxing treatment has successfully deposited neutral red, acid red, Nano-TiO2, and chitosan at wood surfaces. However, some pits in A2 = beeswax + acid red + nano-TiO2, were not filled, indicating non-uniform distribution of the modified beeswax directly mixed with acidic red and nano-TiO2 into the compressed poplar wood. The modified wax compressed poplar X-ray surface energy spectra. (a) A1 = beeswax + acid red; (b) A2 = beeswax + acid red + nano-TiO 2 ; (c) A3 = beeswax + acid red + chitosan; (d) B1 = beeswax + neutral red; (e) B2 = beeswax + neutral red + nano-TiO 2 ; (f) B3 = beeswax + neutral red + chitosan.

Permeability of Modified Beeswax on the Surface of Compressed Poplar Wood
In Figure 3, it can be clearly seen that samples A1 = beeswax + acid red, A3 = beeswax + acid red + chitosan, B1 = beeswax + neutral red, B2 = beeswax + neutral red + nano-TiO 2 , and B3 = beeswax + neutral red + chitosan, have pits on the radial section of compressed poplar wood that are filled with Materials 2016, 9, 230 6 of 11 modified beeswax. This indicates that hot waxing treatment has successfully deposited neutral red, acid red, Nano-TiO 2 , and chitosan at wood surfaces. However, some pits in A2 = beeswax + acid red + nano-TiO 2 , were not filled, indicating non-uniform distribution of the modified beeswax directly mixed with acidic red and nano-TiO 2 into the compressed poplar wood. According to the fully filled pits of B3 = beeswax + neutral red + chitosan, the penetration of the beeswax modified by neutral red and chitosan was optimum. According to the fully filled pits of B3 = beeswax + neutral red + chitosan, the penetration of the beeswax modified by neutral red and chitosan was optimum.
In summary, the wood specimens treated by the beeswax modified with 0.2% nano-TiO2 and 0.05% neutral red dye had the smallest change in colorimetric parameters. This indicates that this modification can provide short-term (60 h) protection to wood against the UV and inhibit light-induced discoloration of the wood [19].

Surface Colorimetric Parameters of Modified Beeswax-Treated Compressed Poplar Wood
In Figure 4, the ∆L* of A1 = beeswax + acid red, A2 = beeswax + acid red + nano-TiO 2 , A3 = beeswax + acid red + chitosan, B1 = beeswax + neutral red, B2 = beeswax + neutral red + nano-TiO 2 , and B3 = beeswax + neutral red + chitosan, was´12.038,´7.9,´9.146,´3.08,´2.43, and 2.62, respectively. A1 = beeswax + acid red, shows the largest curve amplitude, and the curve is at the bottommost location, indicating the maximum ∆L*. The B2 = beeswax + neutral red + nano-TiO 2 , curve is located in the middle, indicating the minimum ∆L*. B3 = beeswax + neutral red + chitosan and B2 = beeswax + neutral red + nano-TiO 2 , are the most stable among ∆a* curves, and their ∆a* values were´2.62 and´2.436, respectively. In terms of ∆b* curve, A1 has the largest change, while B3 = beeswax + neutral red + chitosan and B2 = beeswax + neutral red + nano-TiO 2 changed the least. In the ∆E* curve, the color difference of B2 = beeswax + neutral red + nano-TiO 2 was 4.838, and that of B3 = beeswax + neutral red + chitosan was 5.792, about 20% higher than the former. In Figure 5, after 60h UV-irradiation, there is no big change for the six kinds of modified beeswax wax material and pure beeswax wax. This suggests that modified wax has good aging resistance, as the color change of B2 = beeswax + neutral red + nano-TiO 2 and B3 = beeswax + neutral red + chitosan was minimal.
In summary, the wood specimens treated by the beeswax modified with 0.2% nano-TiO 2 and 0.05% neutral red dye had the smallest change in colorimetric parameters. This indicates that this modification can provide short-term (60 h) protection to wood against the UV and inhibit light-induced discoloration of the wood [19].

Surface Hydrophobicity of Modified Beeswax-Treated Compressed Poplar Wood
It can be seen in Figure 6 that the initial contact angles of all the wood specimens subject to hot waxing were over 100°, reaching a high level of hydrophobicity, while the contact angle of the unwaxed base material was 70°, lacking hydrophobicity. The contact angles of specimen B2 = beeswax + neutral red + nano-TiO2 and B3 =beeswax + neutral red + chitosan, after UV exposure for 60 h were 116° and 121°, higher by 4°-11° compared with B1 = beeswax + neutral red, B2 = beeswax + neutral red + nano-TiO2, and B3 = beeswax + neutral red + chitosan. These results indicate that the

Surface Hydrophobicity of Modified Beeswax-Treated Compressed Poplar Wood
It can be seen in Figure 6 that the initial contact angles of all the wood specimens subject to hot waxing were over 100°, reaching a high level of hydrophobicity, while the contact angle of the unwaxed base material was 70°, lacking hydrophobicity. The contact angles of specimen B2 = beeswax + neutral red + nano-TiO2 and B3 =beeswax + neutral red + chitosan, after UV exposure for 60 h were 116° and 121°, higher by 4°-11° compared with B1 = beeswax + neutral red, B2 = beeswax + neutral red + nano-TiO2, and B3 = beeswax + neutral red + chitosan. These results indicate that the

Surface Hydrophobicity of Modified Beeswax-Treated Compressed Poplar Wood
It can be seen in Figure 6 that the initial contact angles of all the wood specimens subject to hot waxing were over 100˝, reaching a high level of hydrophobicity, while the contact angle of the unwaxed base material was 70˝, lacking hydrophobicity. The contact angles of specimen B2 = beeswax + neutral red + nano-TiO 2 and B3 =beeswax + neutral red + chitosan, after UV exposure for 60 h were 116˝and 121˝, higher by 4˝-11˝compared with B1 = beeswax + neutral red, B2 = beeswax + Materials 2016, 9, 230 8 of 11 neutral red + nano-TiO 2 , and B3 = beeswax + neutral red + chitosan. These results indicate that the B2 = beeswax + neutral red + nano-TiO 2 and B3 = beeswax + neutral red + chitosan, specimens slightly improved surface hydrophobicity. The contact angles of A1 = beeswax + acid red, A2 = beeswax + acid red + nano-TiO 2 , A3 = beeswax + acid red + chitosan, and B1 = beeswax + neutral red also remained over 100˝. Their contact angles reduced by about 1-1.05 times compared with B2 = beeswax + neutral red + nano-TiO 2 and by 1-1.1 times compared with B3 = beeswax + neutral red + chitosan.
Materials 2016, 9,230 8 of 10 B2 = beeswax + neutral red + nano-TiO2 and B3 = beeswax + neutral red + chitosan, specimens slightly improved surface hydrophobicity. The contact angles of A1 = beeswax + acid red, A2 = beeswax + acid red + nano-TiO2, A3 = beeswax + acid red + chitosan, and B1 = beeswax + neutral red also remained over 100°. Their contact angles reduced by about 1-1.05 times compared with B2 = beeswax + neutral red + nano-TiO2 and by 1-1.1 times compared with B3 = beeswax + neutral red + chitosan. In summary, the wax will go into wood pores and form a thin layer at the wood surface, effectively improving the hydrophobicity of wood surfaces. The application of acid dye, neutral dye, chitosan, and nano-TiO2 can reduce UV damage to the surface wax layer. Since the contact angle of B3 = beeswax + neutral red + chitosan had the smallest reduction, the wood hydrophobicity was strongest after the treatment of the beeswax was modified by 0.2% chitosan and 0.05% neutral red dye.

Influence of Hot Waxing of Modified Beeswax on the Surface Gloss of Compressed Poplar Wood
As can be seen in Figure 7, the gloss values of A2, A3, and B1 along and across the grain were all lower than those of A1, B2, and B3. Therein, the gloss value of B3 along the grain was 1.03% and 1% higher than those of A1 and B2, respectively. Additionally, the gloss value of B3 across the grain was also higher by 1.03% and 1.1% respectively compared with the latter two.
In summary, the impact of short-term exposure to UV radiation on the surface gloss of wood is generally small. The gloss values of B2 = beeswax + neutral red + nano-TiO2 were slightly lower than those of B3 = beeswax + neutral red + chitosan. This is possibly because the addition of nano-TiO2 and acid dye resulted in an increased roughness of the wax layer, and UV light would scatter at the rough surface to form a matting effect, thereby reducing the surface gloss (of B2). The surface gloss of B3 = beeswax + neutral red + chitosan was the closest to the +++TL, i.e. the modification by 0.2% chitosan and 0.2% neutral red dye brought about the best wood surface gloss.  In summary, the wax will go into wood pores and form a thin layer at the wood surface, effectively improving the hydrophobicity of wood surfaces. The application of acid dye, neutral dye, chitosan, and nano-TiO 2 can reduce UV damage to the surface wax layer. Since the contact angle of B3 = beeswax + neutral red + chitosan had the smallest reduction, the wood hydrophobicity was strongest after the treatment of the beeswax was modified by 0.2% chitosan and 0.05% neutral red dye.

Influence of Hot Waxing of Modified Beeswax on the Surface Gloss of Compressed Poplar Wood
As can be seen in Figure 7, the gloss values of A2, A3, and B1 along and across the grain were all lower than those of A1, B2, and B3. Therein, the gloss value of B3 along the grain was 1.03% and 1% higher than those of A1 and B2, respectively. Additionally, the gloss value of B3 across the grain was also higher by 1.03% and 1.1% respectively compared with the latter two.
Materials 2016, 9,230 8 of 10 B2 = beeswax + neutral red + nano-TiO2 and B3 = beeswax + neutral red + chitosan, specimens slightly improved surface hydrophobicity. The contact angles of A1 = beeswax + acid red, A2 = beeswax + acid red + nano-TiO2, A3 = beeswax + acid red + chitosan, and B1 = beeswax + neutral red also remained over 100°. Their contact angles reduced by about 1-1.05 times compared with B2 = beeswax + neutral red + nano-TiO2 and by 1-1.1 times compared with B3 = beeswax + neutral red + chitosan. In summary, the wax will go into wood pores and form a thin layer at the wood surface, effectively improving the hydrophobicity of wood surfaces. The application of acid dye, neutral dye, chitosan, and nano-TiO2 can reduce UV damage to the surface wax layer. Since the contact angle of B3 = beeswax + neutral red + chitosan had the smallest reduction, the wood hydrophobicity was strongest after the treatment of the beeswax was modified by 0.2% chitosan and 0.05% neutral red dye.

Influence of Hot Waxing of Modified Beeswax on the Surface Gloss of Compressed Poplar Wood
As can be seen in Figure 7, the gloss values of A2, A3, and B1 along and across the grain were all lower than those of A1, B2, and B3. Therein, the gloss value of B3 along the grain was 1.03% and 1% higher than those of A1 and B2, respectively. Additionally, the gloss value of B3 across the grain was also higher by 1.03% and 1.1% respectively compared with the latter two.
In summary, the impact of short-term exposure to UV radiation on the surface gloss of wood is generally small. The gloss values of B2 = beeswax + neutral red + nano-TiO2 were slightly lower than those of B3 = beeswax + neutral red + chitosan. This is possibly because the addition of nano-TiO2 and acid dye resulted in an increased roughness of the wax layer, and UV light would scatter at the rough surface to form a matting effect, thereby reducing the surface gloss (of B2). The surface gloss of B3 = beeswax + neutral red + chitosan was the closest to the +++TL, i.e. the modification by 0.2% chitosan and 0.2% neutral red dye brought about the best wood surface gloss.  In summary, the impact of short-term exposure to UV radiation on the surface gloss of wood is generally small. The gloss values of B2 = beeswax + neutral red + nano-TiO 2 were slightly lower than those of B3 = beeswax + neutral red + chitosan. This is possibly because the addition of nano-TiO 2 and acid dye resulted in an increased roughness of the wax layer, and UV light would scatter at the rough surface to form a matting effect, thereby reducing the surface gloss (of B2). The surface gloss of B3 = beeswax + neutral red + chitosan was the closest to the +++TL, i.e. the modification by 0.2% chitosan and 0.2% neutral red dye brought about the best wood surface gloss.

Surface Texture of Modified Beeswax-Treated Compressed Poplar Wood
It is clearly understood from wavelet analysis that as ELL (the low frequency LL subgraph of wavelet analysis on the second scale) reduces and as EHL (the medium-high frequency HL subgraph of wavelet analysis on the second scale of vertical edge), ELH (the medium-high frequency LH subgraph of wavelet analysis on the second scale of horizontal edge), and EHH (the high frequency HH subgraph of wavelet analysis on the second scale of diagonal edge) increased, the wood grain became increasingly coarse and deep, indicating that the surface texture of modified beeswax-treated compressed poplar wood became more pronounced In Figure 8, with the increase of irradiation time, the energy-value curves of specimens in the four subgraphs at 12-48 h have gone up or down. However, in general, all curves show a declining trend, indicating that the texture of the specimens became less conspicuous possibly because of the UV-induced aging of the wax layer. After 48 h of UV irradiation, B3 = beeswax + neutral red + chitosan, had the largest decline of 250.1 in subgraph LL, while B1 had the smallest decline of 10.4, indicating a minimum change in B1 = beeswax + neutral red. B3 = beeswax + neutral red + chitosan in subgraph LH had the lowest decline, being only 0.1. Its decline was also the smallest in subgraph HL and HH. This indicates that B3 = beeswax + neutral red + chitosan, treated by the beeswax modified by 0.5% chitosan and 0.2% neutral red dye, maintained its surface texture to a greater extent than the other specimens.

Surface Texture of Modified Beeswax-Treated Compressed Poplar Wood
It is clearly understood from wavelet analysis that as ELL (the low frequency LL subgraph of wavelet analysis on the second scale) reduces and as EHL (the medium-high frequency HL subgraph of wavelet analysis on the second scale of vertical edge), ELH (the medium-high frequency LH subgraph of wavelet analysis on the second scale of horizontal edge), and EHH (the high frequency HH subgraph of wavelet analysis on the second scale of diagonal edge) increased, the wood grain became increasingly coarse and deep, indicating that the surface texture of modified beeswax-treated compressed poplar wood became more pronounced In Figure 8, with the increase of irradiation time, the energy-value curves of specimens in the four subgraphs at 12-48h have gone up or down. However, in general, all curves show a declining trend, indicating that the texture of the specimens became less conspicuous possibly because of the UV-induced aging of the wax layer. After 48 h of UV irradiation, B3 = beeswax + neutral red + chitosan, had the largest decline of 250.1 in subgraph LL, while B1 had the smallest decline of 10.4, indicating a minimum change in B1 = beeswax + neutral red. B3 = beeswax + neutral red + chitosan in subgraph LH had the lowest decline, being only 0.1. Its decline was also the smallest in subgraph HL and HH. This indicates that B3 = beeswax + neutral red + chitosan, treated by the beeswax modified by 0.5% chitosan and 0.2% neutral red dye, maintained its surface texture to a greater extent than the other specimens.

Conclusions
In conclusion, a mixture of 10% beeswax, 0.05% neutral red, and 0.2% chitosan was the most effective treatment. The direct mixing of 0.05% neutral dye and 0.2% chitosan into 10% beeswax can produce the greatest improvement for the surface performance of compressed poplar wood after hot waxing. As a result of treatment with such modified beeswax, the poplar wood can maintain its

Conclusions
In conclusion, a mixture of 10% beeswax, 0.05% neutral red, and 0.2% chitosan was the most effective treatment. The direct mixing of 0.05% neutral dye and 0.2% chitosan into 10% beeswax can produce the greatest improvement for the surface performance of compressed poplar wood after hot waxing. As a result of treatment with such modified beeswax, the poplar wood can maintain its color and physical and mechanical properties, including dimensional stability, and it can be used in both dry and damp environments. This provides a high-quality material for furniture and woodcarving production at a lower cost and simultaneously improves the use value of broad-leaved fast-growing species.