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Bakir, D. (2022). "Effects of different incising pretreatments in improving permeability in two refractory wood species," BioResources 17(3), 5021-5037.

Abstract

For many product and applications, the penetration of preservatives or modification substances into wood species should be deep and homogeneous. Caucasian spruce and European larch are resistant to impregnation. This study compared how different incising pre-processes increased the retention of impregnation materials and the depth of their penetration into the structures of these refractory wood species. Mechanical, biological, and laser incising pretreatments were applied to increase the permeability of sapwood samples before the impregnation. To compare the uptake of the wood preservatives transverse and longitudinal to the axial tracheids in the samples, the cross-sections of some of the samples that had been subjected to different incising pretreatments were covered with a polyurethane-based paint. All wood samples were impregnated using a vacuum method with Celcure C4 new generation preservatives. The study compared the possible effects of these different incising pretreatments on the uptake of preservatives into the tracheids in the spruce and larch woods in both longitudinal and transverse directions. The results showed that the copper (Cu) uptake levels increased in these refractory wood species, especially in the transverse direction, after the different incising pretreatments. Moreover, the results showed it is very important to choose the most suitable pretreatment method for the refractory tree species before impregnation.


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Effects of Different Incising Pretreatments in Improving Permeability in Two Refractory Wood Species

Davut Bakir *

For many product and applications, the penetration of preservatives or modification substances into wood species should be deep and homogeneous. Caucasian spruce and European larch are resistant to impregnation. This study compared how different incising pre-processes increased the retention of impregnation materials and the depth of their penetration into the structures of these refractory wood species. Mechanical, biological, and laser incising pretreatments were applied to increase the permeability of sapwood samples before the impregnation. To compare the uptake of the wood preservatives transverse and longitudinal to the axial tracheids in the samples, the cross-sections of some of the samples that had been subjected to different incising pretreatments were covered with a polyurethane-based paint. All wood samples were impregnated using a vacuum method with Celcure C4 new generation preservatives. The study compared the possible effects of these different incising pretreatments on the uptake of preservatives into the tracheids in the spruce and larch woods in both longitudinal and transverse directions. The results showed that the copper (Cu) uptake levels increased in these refractory wood species, especially in the transverse direction, after the different incising pretreatments. Moreover, the results showed it is very important to choose the most suitable pretreatment method for the refractory tree species before impregnation.

DOI: 10.15376/biores.17.3.5021-5037

Keywords: Caucasian spruce; European larch; Permeability; Mechanical incising; Bioincising; Laser incising

Contact information: Department of Forest Biology and Wood Protection Technology, Faculty of Forestry, Artvin Çoruh University, Artvin, Turkey; *Corresponding author: davut.bakir23@gmail.com

INTRODUCTION

High permeability is desirable when applying preservatives and wood-modification substances to protect wood against fungi, wood-boring insects, marine-boring organisms, and other harmful factors or to increase specific wood properties. For many product and applications, the penetration of preservative solutions and modification substances into wood should be deep and homogeneous (Lehringer et al. 2010; Dale et al. 2019; Nath et al. 2020a,b). Therefore, it is very important for the forestry industry to increase the permeability of wood species that are resistant to impregnation. One of the industry’s solutions to increase the permeability of both refractory wood species and the heartwood parts of trees is the use of different incising methods. Incising improves intracellular fluid flow in woods with low permeability during preservative treatment processes (Nath et al. 2020a,b). For example, the presence of pit aspiration and extractives in Douglas fir wood and in Japanese hybrid woods (Japanese larch and Sakhalin fir), is what causes these tree species to be classified as very resistant to impregnation. To allow the wood of such species to be impregnated to a minimum level of retention and penetration, it is recommended that they be incised before the impregnation process (Islam et al. 2007).

The use of mechanical and laser incising methods improves the treatability of both heartwood and the sapwood of resistant-to-impregnate tree species. Studies on the mechanical incising and treatability of refractory wood species have generally focused on the penetration and retention levels of treated wood (Perrin 1978; Morris 1995; Winandy et al. 1995; Kartal 2002) and their effects on mechanical strength (Winandy and Morrell 1998; Winandy et al. 2022). On the other hand, studies on laser incising have related to improving the permeability of wood (Ruddick 1991), the interaction of laser beams with the anatomical properties of wood (Wang et al. 2013; Nath et al. 2020a, 2022), the effect of laser incising on the strength properties of wood (Suzuki et al. 1996; Morrell et al. 1998; Kortsalioudakis et al. 2015), and the effects of laser incising on the chemical properties of the regions of wood tissue affected by the laser beam heat (Barcikowski et al. 2006; Wang et al. 2013).

There are also some studies on various non-biological permeability enhancing methods. These include the cryogenic treatment (Yorur and Kayahan 2018), extraction treatment (Iida et al. 2002), microwave treatment (Listyanto et al. 2013; Xu et al. 2015; Poonia et al. 2016; Terziev et al. 2020), pre-compression (Chech 1971; Watanabe et al. 1998; Kortsalioudakis et al. 2015), pre-freezing (Erickson and Peterson 1969; Cooper et al. 1970), pre-steaming (Simpson 1976; Harris et al. 1989; Hansmann et al. 2002; Dashti et al. 2012), and smoke heating (Ishiguri et al. 2003). There are also studies that focused on bleach (sodium hypochlorite (NaClO)) and acid treatment (Yıldız et al. 2008).

Bacteria (Ünligil 1972; Clausen 1995; Kobayashi et al. 1998a,b; Hansmann et al. 2002; Pánek and Reinprecht 2011; Yıldız et al. 2012; Tajrishi et al. 2021), enzymes (Durmaz et al. 2015), and blue stain fungi (Lehringer et al. 2010; Danihelová et al. 2018) have also been used to increase the permeability of wood. In the forest products industry, the impact of controlled decay by wood rot fungi has been studied for years. It is one of the biotechnological applications used to increase the permeability of wood, because it does not have excessively harmful effects on other wood properties, especially on the mechanical strength (Fuhr et al. 2012a, b; Fuhr et al. 2013; Schubert et al. 2013; Gilani et al. 2014; Schubert et al. 2014; Gilani and Schwarze 2015; Emaminasab et al. 2016; Dale et al. 2019; Chang et al. 2020; Bakir et al. 2021a,b; Tajrishi et al. 2021; Bakir et al. 2022).

In this study, three different incising pretreatments were applied, and their effectiveness in increasing the permeability of two different refractory wood species was compared. This first pretreatment was bioincising. The biotechnological method of bioincising increases the uptake of impregnation in low-permeability wood species such as spruce by incubating Physisporinus vitreus, a white rot fungus that belongs to the Basidiomycetes class (Lehringer et al. 2009b; Lehringer et al. 2010; Schubert and Schwarze 2011). The second pretreatment was mechanical incising, where small slits are opened in the wood by running toothed rollers parallel to the fibers (Perrin 1978; Winandy et al. 1995; Morris 1995). The third pretreatment was laser incising, where a high-powered carbon dioxide (CO2) laser creates deep needle-shaped cavities in the wood. This improves the liquid impregnation capacity and results in a higher liquid penetration rate (Nath et al. 2020a,b).

There have been many studies on increasing the permeability of wood species that are resistant to impregnation. However, there have been no studies on the comparative effects of these different incising methods on the uptake and penetration of new generation copper (Cu)-containing wood preservatives. Many up-to-date scientific studies have been conducted at the micro level with biotechnological methods and laser applications, but their significance has not been explored further. The importance of the present study lies in its comparison of mechanical incising as well as bio- and laser incision at the macro level.

EXPERIMENTAL

Test Materials

Defect-free, kiln-dried sapwood samples were obtained from Caucasian spruce (Picea orientalis L. Link) grown in the Artvin province of Turkey and European larch (Larix decidua Mill.) grown in Karabula in the Krasnoyarskiy Kray region of Russia. All wood samples measured 120 mm × 30 mm × 30 mm (longitudinal × radial × tangential). The samples were shortly end-matched; therefore, for each species, they were cut out of the same original full-length parent boards and then allocated to different treatments. Eventually, there were 20 samples of spruce sapwood impregnated without pretreatment, 20 samples of larch sapwood impregnated without pretreatment, 20 samples of spruce sapwood impregnated after bioincising pretreatment, 20 samples of larch sapwood impregnated after bioincising pretreatment, 20 samples of spruce sapwood impregnated after mechanical incising pretreatment, 20 samples of larch sapwood impregnated after mechanical incising pretreatment, 20 samples of spruce sapwood impregnated after laser incising pretreatment, and 20 samples of larch sapwood impregnated after laser incising pretreatment. The samples were selected so that their growth rings corresponded as closely as possible to minimize any influence of natural variability. The radial and tangential orientation of the growth rings were strictly maintained.

Bioincising Pretreatment

Before the bioincising pretreatments, the wood samples were conditioned for 2 weeks in a climate chamber at 20 ℃ and 65% relative humidity. Glass jars with dimensions of 170 mm × 100 mm × 100 mm (length × width × height) were used in the bioincising process because the wood samples required a larger volume than that of the Kolle flasks required in the BS EN 113-1 (2020) standard. The metal lids of the jars used in the P. vitreus incubation processes were first pierced in a circle with a punch tool. The hole was clogged with cotton wool to meet the air and humidity requirement of the fungi in the climate chamber more easily. The wood samples were placed directly into the glass jars, which already contained 4% malt extract agar (MEA) nutrient medium previously inoculated with the fungal strain. Wet vermiculite was also added under sterile conditions. The air-dried sapwood samples were exposed to P. vitreus FP 103669-T white rot fungus for 8 weeks at 26 ℃ and 75% relative humidity to induce a weight loss of approximately 10%. From the literature, a weight loss of 10% from minor strength losses of less than 10% in the wood by bioincising was considered. The efficiency of the incubation periods and proper growth of P. vitreus depend on all conditions (i.e., nutrient, temperature, water activity, oxygen, and pH) being favorable. Homogeneous bio-incising depends on the complete coverage of the wood surface. For a successful upscaling to industrial application, construction, and other mass loading applications, a uniform colonization of the substrate and controlled fungal activity must be achieved to ensure a homogenous distribution of wood modification substances (Fig. 1).

Fig. 1. Images of the a) heterogeneous and b) homogeneous colonization of wood samples by P. vitreus fungus in glass jars

The kiln-dried samples were weighed before and after the bioincising. The percentage weight loss of each sample after bioincising was then calculated according to Eq. 1,

(1)

where WL is the weight loss of the sample (%), W0 is the oven-dried weight of the sample before treatment (g), and W1 is the oven-dried weight of samples after treatment (g).

Mechanical Incising Pretreatment

Some Caucasian spruce and European larch samples were mechanically incised using the same incision density pattern (10,000 incisions/m2) (Fig. 2), incision depth (10 mm), and diameter (2 mm). The radial and tangential surfaces of the samples were mechanically incised (Fig. 3). Before the mechanical incising pretreatments, the wood samples were conditioned for 2 weeks in a climate chamber at 20 ℃ and 65% relative humidity.

Fig. 2. Mechanical and laser incising patterns on radial and tangential surfaces and distances between holes in transverse and longitudinal directions

Fig. 3. Images depicting the a) preparation of a wood surface die (10,000 incision/m2) for all mechanical incising operations, b) the depth of the spade drill bit (10 mm), and c) the incision of wood samples by the spade drill bit

The oven-dried samples were weighed before and after the mechanical incising pretreatments. The percentage weight loss of each sample after mechanical incising was then calculated according to Eq. 1.

Laser Incising Pretreatment

The holes were drilled with a CO2 laser (VLS6.60; Universal Laser Systems, Scottsdale, AZ, USA) in the radial and tangential surfaces of the Caucasian spruce and European larch samples by controlling the irradiating time with power at 60 W, a speed setting of 4.0 m/s, and a high 30 mm. The same incising pattern was used for all specimens, as shown in Fig. 4. The incising density was the same for both the mechanical incising and the laser incising pretreatment, i.e., 10,000 holes/m2 (Fig. 2), drilled to a depth of 10 mm and with a diameter of 2 mm for each incision (Islam et al. 2008).

Fig. 4. The incision of wood samples by a CO2 laser

The oven-dried samples were weighed before and after the laser incising pretreatment, and the percentage weight loss of each sample after laser incising was then calculated according to Eq. 1.

Impregnation Treatments

Some spruce and larch sapwood samples were not treated with any incising process so that they could serve as controls. Together with the pre-incised spruce and larch sapwood samples, they were subsequently treated with Celcure C4 wood preservative solution to detect and compare the permeability of the samples. Celcure C4 is a water-based wood preservative that contains an alkaline copper quaternary system and two organic co-biocides (benzalkonium chloride and cyproconazole). In determining the concentration of the preservative solution, based on market share and, more importantly, direct exposure route, the present study focused on materials rated for above-ground use. So, the concentration of Celcure C4 solution for impregnation processes was 3%. Vacuum methods (40 min, 40 mbar) were applied in the impregnation processes according to the BS EN 113-1 (2020) standard. Some samples’ end-grain surfaces (cross sections) were sealed with a polyurethane coating before treatment to compare the uptake in the transverse directions of preservative solutions into these surfaces. On the other hand, the other samples’ longitudinal surfaces (radial and tangential sections) are sealed with polyurethane coatings to determine the uptake in the longitudinal directions. The preservative-treated samples were then stored at 20 °C for 2 weeks for a good fixation of the preservatives. Table 1 shows the test samples and procedures followed in the study.

Table 1. Test Samples and Procedures Followed in the Study

Determination of the Preservative Solution Uptake

The solution uptake in the samples was calculated as the difference between the wet weight of the wood samples after impregnation and the air-dried initial weight before impregnation, according to the BS EN 113-1 (2020) standard. To evaluate the penetration of Cu, the untreated and various pre-incised wood samples were cross-sectioned in the middle, and the penetration of copper was measured after spraying with Chrome azurol S solution (a color indicator of copper) based on the AWPA A69-18 (2021) standard method.

Statistical Analysis

For statistical evaluations, analysis of variance (ANOVA) was used to compare several groups of observations. Using Tukey’s test, all the data were statistically compared to identify significant differences at 0.05 probabilities among the mean values of the studied properties within the applications. The ANOVA and the least significant difference tests were conducted using JMP 5.0 statistical software (SAS Institute, Cary, NC, USA).

RESULTS AND DISCUSSION

Differences in Weight Losses from Different Incising Pretreatments

In recent years, there has been a great interest in determining the changes in the physical and mechanical properties of wood as a result of different incising processes because it is important that the physical properties must not be negatively altered and that the treatment should not weaken its mechanical properties after all incising pretreatments. So, Table 2 compared the differences in weight losses in the spruce and larch sapwood samples after the different incising pretreatments. Although there was a significant difference among the bioincising, mechanical incising, and laser incising pretreatments in both spruce and larch sapwoods, there was no significant difference between the same pretreatments of the spruce and larch sapwood samples, except for laser incising.

Table 2. Weight Loss in the Spruce and Larch Sapwood Samples after Bioincising, Mechanical Incising, and Laser Incising Pretreatments

As shown in Table 2, the weight losses in the spruce and larch sapwood samples after different pretreatments were higher in bioincised samples than in the laser and mechanical incising samples. P. vitreus is a wood decay fungus that can show different degradation patterns in the spruce and larch wood samples. However, when mechanical and laser incising processes are applied, only certain parts of the wood tissue are affected, while the entire wood tissue is affected by bioincising processes. Laser and mechanical incising interactions with the refractory wood tissues resulted in local and shallower holes, whereas the fungal hyphae can reach deeper in the bioincising process. Laser incising pretreatments resulted in more weight losses in larch samples than in spruce samples. Nath et al. (2020a) reported that wood anatomy and density had a major influence on the effect of CO2 laser incising when incised at the same CO2 laser power. In addition, denser woods are more difficult to ablate or incise (Fukuta et al. 2016; Nath et al. 2020b). Nath et al. (2020b) reported the ablation to be greater in lower-density springwood than in latewood of CO2-TEA (Transverse Excitation Atmospheric) laser-incised pine. In addition, a lower-wavelength laser was shown to give improved incising in dense wood (Nath et al. 2020b).

Using Chrome Azurol-S Reagent to Detect the Cu Uptake Levels

Impregnating cross-sections of spruce and larch sapwood samples with chrome azurol-S solution displayed the presence of Cu, since a blue color denotes a positive response (Fig. 5). Because it is a practical, quick, and cheap method of detecting Cu, chrome azurol-S solution is commonly used in wood treatment studies (Milanez et al. 2017).

Figure 5 demonstrates that, as a result of the different incising pretreatments, much more wood preservative was absorbed in the Caucasian spruce sapwood samples than in the European larch sapwood samples. The types and prevalence of the resins or some extractives in larch sapwood are believed to promote decreasing preservative uptakes. Larch sapwood has higher resin/extractives content than spruce sapwood (Lüxford 1953; Wu and Hu 1997; Wagner 2010). Matsumura et al. (1996) stated that resin removal increased the permeability of Japanese larch heartwood. They found significant correlations between the permeability of samples and the methanol-soluble extractive content. A relation was also found between permeability and the number of resin canals. Similar results were also reported by Ahmed et al. (2012) for the resin content. Its distribution may influence a uniform liquid penetration in dried lumber, particularly when resins are migratory at elevated temperatures (Lu et al. 1992; Ahmed et al. 2012). Caucasian spruce sapwood samples showed that Cu uptake levels after laser and mechanical incising pretreatments were higher than those in the control and bioincised spruce samples (Fig. 5a). In the European larch sapwood samples, Cu uptake levels in bioincised larch samples were higher than in the control samples and in samples pre-incised with other incising processes (Fig. 5b). The results are shown in Table 3 to support these findings.

Fig. 5. Using chrome azurol-S reagent to detect Cu uptake levels in a) Caucasian spruce and b) European larch wood samples. The blue colors show positive responses.

Uptake of Preservatives in Transverse and Longitudinal Directions

Table 3 shows the Cu uptake levels (kg/m3) in the spruce and larch sapwood samples before and after different incising pretreatments. The end-grain surfaces of some samples were sealed with polyurethane, which presented the Cu uptake levels in the transverse directions of the preservative solutions. Unincised wood samples served as the controls to compare the effects of different pretreatments on the permeability of spruce and larch sapwood samples. As the end-grain surfaces of samples were sealed with polyurethane in the spruce and larch samples, Cu uptake levels by Celcure C4 treatment generally decreased in all pretreatments, except for the bioincising pretreatment of larch sapwood samples. However, no statistically significant changes were observed in the mechanical and laser incising pretreatments of spruce samples, or in the control and bioincising pretreatment of larch samples.

The results for the different pretreatments of spruce samples showed that the uptake of preservatives in the longitudinal directions was higher than the uptake in the transverse directions in the control and in all the pre-incised wood samples. Nath et al. (2020b) expressed a similar finding. However, no differences were determined for the mechanically and laser incised spruce samples. Similar results were also determined for the control and in all the pretreatments of the larch sapwood samples, except for the bioincising pretreatment. However, there were not significant differences in the uptake of preservatives in different directions in the control and the various pre-incised larch sapwood samples (Table 3).

Table 3. Cu Uptake Levels (kg/m3) in Impregnated Spruce and Larch Samples Before and After Bioincising, Mechanical Incising, and Laser Incising Pretreatments

Although mechanical incising methods have, to date, proven most effective in assisting in the transverse permeability of wood (Nath et al. 2020a), the present study found laser incising to be partially more effective than mechanical incising in the transverse directions in the spruce sapwood.

The Cu uptake in the laser and mechanically incised spruce sapwood samples with polyurethane sealing end-grain surfaces was higher in the bioincised spruce sapwoods than in those control samples. However, there was no significant difference between the bioincised and control spruce samples. Similarly, there was no significant difference between the laser and mechanically incised spruce samples.

While mechanical incisions are effective for enhancing preservative treatment processes, the technique is limited because small holes or complex incision geometries are difficult or impossible to achieve. Laser-incision is a technique that could eradicate these issues. It would allow finer incisions, more complex incision patterns, and deeper incision holes compared to mechanical incision technologies (Nath et al. 2020a).

As shown in Table 3, in the spruce sapwood samples with polyurethane sealing longitudinal surfaces, no statistically significant change was observed among the control and all pre-incised spruce sapwood samples. Similarly, there was no significant difference between the control and all pre-incised larch sapwood samples in the larch sapwood samples with polyurethane sealing longitudinal surfaces (Table 3).

In general, the Cu uptake was much higher after bioincising pretreatment compared to the control, mechanical, and laser pretreatments in the larch sapwood samples with polyurethane sealing end-grain surfaces. However, there was no significant difference among the control, mechanical, and laser pretreatments. In this study, P. vitreus was more active in larch sapwood than in spruce sapwood samples, with polyurethane sealing end-grain and longitudinal surfaces. It is known that P. vitreus used in the bioincising process selectively delignifies the wood and prefers mainly bordered pits primarily containing pectin in the wood (Schwarze 2007; Lehringer et al. 2009a, 2010; Schubert and Schwarze 2011; Fuhr et al. 2013; Schubert et al. 2013; Gilani and Schwarze 2014). Physisporinus vitreus likely decomposes the aspirated pits in larch sapwood more than in spruce sapwood. However, different amounts of copper in the larch sapwood and spruce sapwood samples may be the result of the chemical components (pectin, cellulose, hemicellulose, and lignin) and substances (extractives, lignans, and phenolic compounds) consumed by P. vitreus, which might be different in larch sapwood and spruce sapwood. In addition, visual observations (Fig. 5) and impregnation treatments (Table 3) indicated that the control samples of larch sapwood samples were very resistant to preservative treatment, likely due to the presence of higher resin than in spruce sapwood (Lüxford 1953; Wu and Hu 1997; Wagner 2010) (Table 3). In other words, it is believed that the types and prevalence of the resins or some extractives in larch sapwood promote the increase of P. vitreus activity.

Fig. 6. Correlation between the weight losses and Cu uptake levels in the impregnated spruce and larch wood samples pre-incised with the three different incising methods

After the different incising treatments in both spruce and larch sapwood samples, it was found that the increases in the Cu uptake levels in the samples with polyurethane sealing end-grain surfaces were higher than the increases in the samples with polyurethane sealing longitudinal surfaces. In these cases, it is more appropriate to interpret the comparisons as percentages, which means that Cu uptake levels increased more in the transverse directions than in the longitudinal directions after the incising treatments. In addition, laser and mechanical incising pretreatments resulted in higher Cu uptake levels in the spruce samples than in the larch samples with polyurethane sealing end-grain and longitudinal surfaces (Table 3). It emerged that wood anatomy and density could play a role in incision efficiency, influencing hole depth, diameter, and circularity, and affecting the liquid flow pathways in the spruce and larch sapwood (Nath et al. 2022). The average wood density in European larch trees (515 to 560 kg/m3) (Karlman et al. 2005) was higher than that in Caucasian spruce trees (401 to 425 kg/m3) (Bozkurt et al. 1993). Nath et al. (2020a) reported that the presence of earlywood and latewood had a significant influence on the incision properties during CO2 laser incising. Moreover, laser interactions with the denser latewood tissues resulted in shallower holes (Nath et al. 2022).

The correlations between the weight losses (%) and changes in the Cu uptake levels (kg/m3) that occurred in the samples by different incising pretreatments in spruce and larch sapwood samples are seen in Fig. 6. Here, while determining the correlations, the sapwood samples belonging to the with polyurethane sealing end-grain and longitudinal surfaces groups were evaluated together, separately for each pretreatment. In general, as weight losses increased, the Cu uptake levels increased in both spruce and larch sapwoods. However, in spruce sapwood samples pre-incised with laser and mechanical incising methods, the lower weight loss levels had the higher Cu uptake levels (Fig. 6).

Lasers for wood processing were initially meant only for cutting, marking, and engraving, and it was thought that laser incising was not economically viable (Kamke and Peralta 1990; Nath et al. 2020b). However, with the further development of laser technologies, it has recently been concluded that laser incising is an efficient technique for creating deep, narrow holes for preservative treatment (Nath et al. 2020a).

CONCLUSIONS

  1. The Cu uptake levels in the spruce and larch sapwood samples pre-incised with different incising methods increased compared to control samples, except for laser incised larch sapwood with polyurethane sealing longitudinal surfaces. Moreover, there was a much greater increase in Cu uptake levels in the various pre-incised spruce and larch sapwood samples with polyurethane sealing end-grain surfaces than in samples with polyurethane sealing longitudinal surfaces.
  2. In this study, P. vitreus was more active and effective in larch sapwood than in spruce sapwood samples, with polyurethane sealing end-grain and longitudinal surfaces. In addition, there was more Cu uptake in the bioincised larch sapwood samples than in the laser and mechanically incised larch samples. On the other hand, Cu uptake was much lower in bioincised spruce sapwood samples than in the mechanically and laser incised spruce samples, especially samples with polyurethane sealing end-grain surfaces. Therefore, it is more appropriate to use the laser and mechanical incising for spruce sapwood, and bioincising for larch sapwood, before impregnation.
  3. Further chemical (the laser and fungus interactions with compounds and extractives of wood) and anatomical studies (the laser and fungus interactions with refractory wood tissues) are needed to understand why P. vitreus increases the permeability of larch sapwood more than that of spruce sapwood, or why laser incising increases the

permeability of spruce sapwood more than that of larch sapwood.

ACKNOWLEDGMENTS

This study was financially supported by The Coordination Unit for Scientific Research Projects (BAP), Artvin Çoruh University (Project No: 2021.F11.02.01). The author would like to thank Professor Doctor S. Nami Kartal and Assoc. Prof. Dr. Evren Terzi for their expert technical assistance. The author would also like to thank Mrs. Rita Rentmeester of USDA Forest Service Forest Products Laboratory, Madison, WI, USA, for preparing the P. vitreus fungal strains.

REFERENCES CITED

Ahmed, S.A., Sehlstedt-Persson, M., Karlsson, O., and Morén, T. (2012). ‘’Uneven distribution of preservative in kiln-dried sapwood lumber of Scots pine: Impact of wood structure and resin allocation,’’ Holzforschung 66(2), 251-258. DOI 10.1515/HF.2011.126

AWPA – A69 (2021). “Standard method to determine the penetration of copper containing preservatives,” Amer. Wood-Preservers’ Assoc., Birmingham, AL, USA.

Bakir, D., Dogu, D., and Kartal, S. N. (2021a). “Anatomical structure and degradation characteristics of bioincised oriental spruce wood by Physisporinus vitreus,” Wood Material Science & Engineering. DOI: 10.1080/17480272.2021.1964594

Bakir, D., Dogu, D., Kartal, S. N., and Terzi, E. (2021b). “Evaluation of pit dimensions and uptake of preservative solutions in wood after permeability improvement by bioincising,” Wood Material Science & Engineering. DOI: 10.1080/17480272.2021.2014956

Bakir, D., Kartal, S. N., Terzi, E., and Dogu, D. (2022). “The effects of bioincising by Physisporinus vitreus on CuO retention and copper element leaching in oriental spruce wood,” Maderas. Ciencia y Tecnología 24(27), 1-23. DOI: 10.4067/s0718-221×2022000100427

Barcikowski, S., Koch, G., and Odermatt, J. (2006). “Characterisation and modification of the heat affected zone during laser material processing of wood and wood composites,” European Journal of Wood and Wood Products 64(2), 94-103. DOI: 10.1007/s00107-005-0028-1

BS EN 113-1 (2020). “Durability of wood and wood-based products. Test method against wood destroying basidiomycetes,” BSI Standards Publication, London, England.

Bozkurt, A. Y., Göker, Y., and Erdin. N. (1993). “Physical and mechanical properties of oriental spruce (Picea orientalis (L.) Link.) grown in a plantation site in Belgrad forest near Istanbul,” Forestist 43, 33-56.

Chang, L., Rong, B., Xu, G., Meng, Q., and Wang, L. (2020). “Mechanical properties, components and decay resistance of Populus davidiana bioincised by Coriolus versicolor,” J. Forestry Res. 31(5), 2023-2029. DOI: 10.1007/s11676-019-00972-3

Chech, M. (1971). “Dynamic transverse compression treatment to improve drying behaviour of yellow birch,” Forest Products Journal 21, 41-50.

Clausen, C. A. (1995). “Bacterial associations with decaying wood: A review,” International Biodetertoration & Biodegradation 37(1-2), 101-107. DOI: 10.1016/0964-8305(95)00109-3

Cooper, G. A., Erickson, R. W., and Haygreen, J. G. (1970). “Drying behaviour of prefrozen black walnut,” Forest Products Journal 20(1), 30-35.

Dale, A., Morris, P. I., Uzunovic, A., Symons, P., and Stirling, R. (2019). “Biological incising of lodgepole pine and white spruce lumber with Dichomitus squalens,” European Journal of Wood and Wood Products 77(6), 1161-1176. DOI: 10.1007/s00107-019-01471-2

Danihelová, A., Reinprecht, L., Spišiak, D., and Hrčka, R. (2018). “Impact of the Norway spruce sapwood treatment with the staining fungus Sydowia polyspora on its permeability and dynamic modulus of elasticity,” Acta Facultatis Xylologiae Zvolen 60(1), 13-18. DOI: 10.17423/afx.2018.60.1.02

Dashti, H., Tarmian, A., Faezipour, M., Hedjazi, S., and Shahverdi, M. (2012). “Effect of presteaming on mass transfer properties of fir wood (Abies alba L.); A gymnosperm species with torus margo pit membrane,” BioResources 7(2), 1907-1918. DOI: 10.15376/biores.7.2.1907-1918

Durmaz, S., Yıldız, U. C., and Yıldız, S. (2015). “Alkaline enzyme treatment of spruce wood to increase permeability,” BioResources 10(3), 4403-4410. DOI: 10.15376/biores.10.3.4403-4410

Emaminasab, M., Tarmian, A., Pourtahmasi, K., and Avramidis, S. (2016). “Improving the permeability of Douglas-fir (Pseudotsuga menziesii) containing compression wood by Physisporinus vitreus and Xylaria longipes,” International Wood Products Journal 7(3), 110-115. DOI: 10.1080/20426445.2016.1155788

Erickson, R. W., and Peterson, H. D. (1969). “The influence of prefreezing and cold water extraction on the shrinkage of wood,” Forest Products Journal 19, 53-58.

Fuhr, M. J., Stührk, C., Münch, B., Schwarze, F. W. M. R., and Schubert, M. (2012a). “Automated quantification of the impact of the wood decay fungus Physisporinus vitreus on the cell wall structure of Norway spruce by tomographic microscopy,” Wood Science and Technology 46(4), 769-779. DOI: 10.1007/s00226-011-0442-y

Fuhr, M. J., Stührk, C., Schubert, M., Schwarze, F. W. M. R., and Herrmann, H. J. (2012b). “Modelling the effect of environmental factors on the hyphal growth of the basidiomycete Physisporinus vitreus,” Journal of Basic Microbiology 52(5), 523-530. DOI: 10.1002/jobm.201100425

Fuhr, M. J., Schubert, M., Stührk, C., Schwarze, F. W. M. R., and Herrmann, H. J. (2013). “Penetration capacity of the wood-decay fungus Physisporinus vitreus,” Complex Adaptive Systems Modeling 1, 1-15. DOI: 10.1186/2194-3206-1-6

Fukuta, S., Nomura, M., Ikeda, T., Yoshizawa, M., Yamasaki, M., and Sasaki, Y. (2016). “Wavelength dependence of machining performance in UV-, VIS- and NIR-laser cutting of wood,” J. Wood Sci. 62(4), 316-323. DOI: 10.1007/s10086-016-1553-8

Gilani, M. S., Boone, M. N., Mader, K., and Schwarze, F. W. M. R. (2014). “Synchrotron X-ray micro-tomography imaging and analysis of wood degraded by Physisporinus vitreus and Xylaria longipes,” Journal of Structural Biology 187(2), 149-157. DOI: 10.1016/j.jsb.2014.06.003

Gilani, M. S., and Schwarze, F. W. M. R. (2015). “Hygric properties of Norway spruce and sycamore after incubation with two white rot fungi,” Holzforschung 69(1), 77-86. DOI: 10.1515/hf-2013-0247

Hansmann, C., Gindl, W., Wimmer, R., and Teischinger, A. (2002). “Permeability of wood – A review,” Wood Research 47(4), 1-16.

Harris, R. A., Schroeder, J. G., and Addis, S. C. (1989). “Steaming of red oak prior to kiln drying: Effects on moisture movement,” Forest Products J. 39(11-12), 70-72.

Iida, I., Yusuf, S., Watanabe, U., and Imamura, Y. (2002). “Liquid penetration of precompressed wood VII: Combined treatment of precompression and extraction in hot water on the liquid penetration of wood,” Journal of Wood Science 48(1), 81-85. DOI: 10.1007/BF00766243

Ishiguri, F., Matsui, M., Andoh, M., Yokota, S., and Yoshizawa, N. (2003). “Time-course changes of chemical and physical properties in sugi (Cryptomeria japonica D. Don) logs during smoke heating,” Wood and Fiber Science 35(4), 585-593.

Islam, N., Ando, K., Yamauchi, H., Kobayashi, Y., and Hattori, N. (2007). “Passive impregnation of liquid in impermeable lumber incised by laser,” Journal of Wood Science 53(5), 436-441. DOI: 10.1007/s10086-006-0878-0

Islam, N., Ando, K., Yamauchi, H., Kobayashi, Y., and Hattori, N. (2008). “Comparative study between full cell and passive impregnation method of wood preservation for laser incised Douglas fir lumber,” Wood Science and Technology 42(4), 343-350. DOI: 10.1007/s00226-007-0168-z

Kamke, F. A., and Peralta, P. N. (1990). “Laser incising for lumber drying,” Forest Products Journal 40(4), 48-54.

Karlman, L., Mörling, T., and Martinsson, O. (2005). “Wood density, annual ring width and latewood content in larch and scots pine,” Eurasian Journal of Forest Research 8(2), 91-96.

Kartal, S. N. (2002). “Effects of incising on treatability and leachability of CCA-C- treated eastern hemlock,” Forest Products Journal 52(2), 44-48.

Kobayashi, Y., Iida, I., Imamura, Y., and Watanabe, U. (1998a). “Improvement of penetrability of sugi wood by impregnation of bacteria using sap-flow method,” Journal of Wood Science 44(6), 482-485. DOI: 10.1007/BF00833414

Kobayashi, Y., Iida, I., Imamura, Y., and Watanabe, U. (1998b). “Drying and anatomical characteristics of sugi wood attacked by bacteria during pond storage,” Journal of Wood Science 44(6), 432- 437. DOI: 10.1007/BF00833406

Kortsalioudakis, N., Petrakis, P., Moustaizis, S., Voulgaridis, E., Adamopoulos, S., Karastergiou, S., and Passialis, C. (2015). “An application of a laser drilling technique to fir and spruce wood specimens to improve their permeability,” in: The 7th International Scientific and Technical Conference, Innovations in Woodworking Industry and Engineering Design, Sofia-Yundola, Bulgaria, pp. 5-13.

Lehringer, C., Richter, K., Schwarze, F. W. M. R., and Militz, H. (2009a). “A review on promising approaches for liquid permeability improvement in softwoods,” Wood and Fiber Science 41(4), 373-385.

Lehringer, C., Arnold, M., Richter, K., Schubert, M., Schwarze, F. W. M. R., and Militz, H. (2009b). “Bioincised wood as substrate for surface modifications,” in: The Fourth European Conference on Wood Modification, Stockholm, Sweden. pp. 197-200.

Lehringer, C., Hillebrand, K., Richter, K., Arnold, M., Schwarze, F. W. M. R., and Militz, H. (2010). “Anatomy of bioincised Norway spruce wood,” International Biodeterioration & Biodegradation 64(5), 346-355. DOI: 10.1016/j.ibiod.2010.03.005

Listyanto, T., Ando, K., Yamauchi, H., and Hattori, N. (2013). “Microwave and steam injection drying of CO2 laser incised sugi lumber,” Journal of Wood Science 59(4), 282-289. DOI: 10.1007/s10086-013-1331-9

Lu, W.-D., Xu, X.-W., Zhao, D.-J., and Tan, H.-Y. (1992). “The quick determination method of resin content in larch wood,” Journal of Northeast Forestry University 3(1), 62-67.

Lüxford, R. F. (1953). ‘’Use of Engelmann spruce for house construction. U.S. For. Prod. Lab. Rept. No. 1944-1. 3 pp.

Matsumura, J., Tsutsumi, J., and Oda, K. (1996). “Effect of water storage and methanol extraction on longitudinal gas permeability of karamatsu heartwood,” Mokuzai Gakkaishi 42(2), 115-121

Milanez, C. R. D., Marcati, C. R., and Machado, S. R. (2017). “Trabeculae and Al-accumulation in the wood cells of Melastomataceae species from Brazilian savanna,” Botany 95(5), 521-530. DOI: 10.1139/cjb-2016-0135

Morrell, J. J., Gupta, R., Winandy, J. E., and Riyanto, D. S. (1998). “Effect of incising and preservative treatment on shear strength of nominal 2-inch lumber,” Journal of the Society of Wood Science and Technology 30(4), 374-381.

Morris, P. I. (1995). “Pasific silver fir is the more treatable component of hem-fir from coastal British Columbia,” Forest Products Journal 45(9), 37-40.

Nath, S., Waugh, D. G., Ormondroyd, G. A., Spear, M. J., Pitman, A. J., Sahoo, S., Curling, S. F., and Mason, P. (2020a). “CO2 laser interactions with wood tissues during single pulse laser-incision,” Optics and Laser Technology 126, article no. 106069, 1-21. DOI: 10.1016/j.optlastec.2020.106069

Nath, S., Waugh, D. G., Ormondroyd, G. A., Spear, M., Pitman, A., Curling, S., and Mason, P. (2020b). “Laser incising of wood: A review,” Lasers in Engineering 45(4-6), 381-403.

Nath, S., Waugh, D. G., Ormondroyd, G. A., Spear, M. J., Curling, S. F., Pitman, A. J., and Mason, P. (2022). “Percussion Nd:YAG laser‑incision of radiata pine: Efects of laser processing parameters and wood anatomy,” Lasers in Manufacturing and Materials Processing 9(2), 173-192. DOI: 10.1007/s40516-022-00169-3

Pánek, M., and Reinprecht, L. (2011). “Bacillus subtilis for improving spruce wood impregnability,” BioResources 6(3), 2912-2931. DOI: 10.15376/biores.6.3.2912-2931

Perrin, P. W. (1978). “Review of incising and its effects on strength and preservative treatment of wood,” Forest Products Journal 28(2), 27-33.

Poonia, P. K., Hom, S. K., Sihag, K., and Tripathi, S. (2016). “Effect of microwave treatment on longitudinal air permeability and preservative uptake characteristics of chir pine wood,” Maderas. Ciencia y Tecnología 18(1), 125-132. DOI: 10.4067/S0718-221X2016005000013

Ruddick, J. N. R. (1991). “Laser incising of Canadian softwood to improve treatability,” Forest Products Journal 41(4), 53-57.

Schubert, M., and Schwarze, F. W. M. R. (2011). “Evaluation of the interspecific competitive ability of the bioincising fungus Physisporinus vitreus,” Journal of Basic Microbiology 51(1), 80-88. DOI: 10.1002/jobm.201000176

Schubert, M., Stührk, C., Fuhr, M. J., and Schwarze, F. W. M. R. (2013). “Agrobacterium-mediated transformation of the white-rot fungus Physiologists vitreus,” Journal of Microbiological Methods 95(2), 251-252. DOI: 10.1016/j.mimet.2013.09.001

Schubert, M., Stührk, C., Fuhr, M. J., and Schwarze, F. W. M. R. (2014). “Imaging hyphal growth of Physisporinus vitreus in Norway spruce wood by means of confocal laser scanning microscopy (CLSM),” Holzforschung 68(6), 727-730. DOI: 10.1515/hf-2013-0183

Simpson, W.T. (1976). “Steaming northern red oak to reduce kiln drying time,” Forest Products Journal 26(10), 35-36.

Suzuki, K., Teduka, Y., Ando, K., Hattori, N., Kitayawa, S., Kato, H., Nagao, H., and Tanaka, T. (1996). “Laser incising of wood, the effect of incising density on bending strength of sugi square lumber (in Japanese),” in: Proceedings of the 46th Annual Meeting of the Japanese Wood Research Society, Kumamoto, Japan, pp.130.

Tajrishi, I. Z., Tarmian, A., Oladi, R., Humar, M., and Ahmadzadh, M. (2021). “Biodegradation and microscale treatability pattern of loblolly pine heartwood bioincised by Bacillus subtilis and Physisporinus vitreus,” Drvna Industrija 72(4), 365-372. DOI: 10.5552/drvind.2021.2034

Terziev, N., Daniel, G., Torgovnikov, G., and Vinden, P. (2020). “Effect of microwave treatment on the wood structure of Norway spruce and radiata pine,” BioResources 15(3), 5616-5626. DOI: 10.15376/biores.15.3.5616-5626

Ünligil, H. H. (1972). “Penetrability and strength of white spruce after ponding,” Forest Products Journal 22, 92-100.

Wagner, J.B. (2010). Seasoning of Wood: A Treatise On the Natural and Artificial Processes Employed in the Preparation of Lumber for Manufacture, with Detailed Explanations of Its Uses, Characteristics and Properties, United States, Kessinger Publishing ISBN: 9781164914815, 26p. DOI.org/10.1002/jctb.5000381205

Wang, Y., Ando, K., and Hattori, N. (2013). “Changes in the anatomy of surface and liquid uptake of wood after laser incising,” Wood Science and Technology 47(3), 447-455. DOI: 10.1007/s00226-012-0497-4

Watanabe, U., Imamura, Y., and Iida, I. (1998). “Liquid penetration of precompressed wood VI: Anatomical characterization of pit fractures,” Journal of Wood Science 44(2), 158-162. DOI: 10.1007/BF00526263

Winandy, J. E., Morrell, J. J., and Lebow, S. T. (1995). “Review of the effects of incising on treatability and strength,” in: Proceedings of Wood Preservation in the 90’s and Beyond, Savannah, GA, USA, pp. 65- 69.

Winandy, J. E., and Morrell, J. J. (1998). “Effects of incising on lumber strength and stiffness: Relationships between incision density and depth, species, and MSR grade,” Wood and Fiber Science 30(2), 185-197.

Winandy, J. E., Hassan, B., and Morrell, J. J. (2022). “Review of the effects of incising on treatability and strength of wood,” Wood Material Science and Engineering. DOI: 10.1080/17480272.2022.2028008

Wu, H., Hau, Z. (1997). “Comparative anatomy of resin ducts of the Pinaceae,” Trees 11, 135-143. DOI: 10.1007/s004680050069

Xu, K., Wang, Y., Lv, J., Li, X., and Wu, Y. (2015). “The effect of microwave pretreatment on the impregnation of poplar wood,” BioResources 10(1), 282-289. DOI: 10.15376/biores.10.1.282-289

Yıldız, S., Dizman, E., and Yıldız, Ü. C. (2008). “Effects of acetic and nitric acid pretreatment on copper content of spruce wood treated with CBA-A and CCA,” in: International Research Group on Wood Preservation 39th Annual Conference, Istanbul, Turkey.

Yıldız, S., Çanakçı, S., Yıldız, Ü. C., Özgenç, Ö., and Tomak, E. D. (2012). “Improving of the impregnability of refractory spruce wood by Bacillus licheniformis pretreatment,” BioResources 7(1), 565-577. DOI: 10.15376/biores.7.1.565-577

Yorur, H., and Kayahan, K. (2018). “Improving impregnation and penetration properties of refractory woods through cryogenic treatment,” BioResources 13(1), 1829-1842. DOI: 10.15376/biores.13.1.1829-1842

Article submitted: June 6, 2022; Peer review completed: June 29, 2022; Revised version received and accepted: July 10, 2022; Published: July 12, 2022.

DOI: 10.15376/biores.17.3.5021-5037