Analysis of the certified forest products market in Japan

As a major importer of forest products, Japan has a significant influence on the global development of forest certification. We examined characteristics of the certified forest products market in Japan. In addition to analysing chain of custody certificate holders using published directories, we conducted a nationwide survey from October to December 2005 of 132 companies that had obtained a chain of custody certificate from one of the certifying bodies in Japan: the Forest Stewardship Council (FSC), the Programme for the Endorsement of Forest Certification, or the Sustainable Green Ecosystem Council. The number of chain of custody certificates has increased since the early 2000s and reached 304 by the end of 2005. FSC-issued certification has dominated certificate distribution, granting 93% of all certificates. Paper products companies have constituted the majority of chain of custody certification holders, receiving two-thirds of the certificates issued. Of survey respondents, 77% had sold certified forest products in 2004. The sales value of certified products reported by 84 respondents totalled 24.3 billion? JPY, of which paper products accounted for 90%. The main certified products sold were paper for plain paper copy and printing, wood chips as raw paper material, and printed material such as environmental reports and calendars. Certified wood products such as sawn goods represented only a small proportion of sales. As with companies in Europe and North America, it was not possible for most Japanese companies to receive premium prices for certified forest products. The unique market characteristics of Japan and Japan’s influence on the certified products trade are discussed.     

Volume yield and profit in the production of clear finger-jointed Scots pine (Pinus sylvestris L.) boards

The aim of this study was to compare the volume yields and contribution margins in the production of clear finger-jointed boards using lower quality raw materials from four suppliers. The study is based on production statistics from 2005 to 2007 and has been carried out in cooperation with a company which manufactures clear finger-jointed boards for mouldings. The raw material was side-boards of Scots pine (Pinus sylvestris L.) with dimensions of 32 by 175 mm². The four raw material suppliers are geographically distributed in different places in Central Sweden. Parallel with the study, a tool for production follow-up has been developed, to make it possible for the company to continuously follow-up its raw material suppliers. The results of the study show that the cheapest raw material gives the highest clear wood volume yield and the highest contribution margin.     

Ring width, latewood proportion and dry density in stems of Pinus brutia Ten.

This study examined basic characteristics of stem wood produced in Pinus brutia Ten. reforestations in Northeastern Greece. Sixteen dominant trees growing at good and medium site qualities were felled at 14–22 years. Site quality classification was based on site quality surrogates and confirmed by using site index curves that were created for a neighbouring area. Discs were taken at three stem positions (base, middle, top) to study variations in ring width, latewood proportion and dry density. Generally, at both good and medium sites, ring width was found to increase towards the top of the stems while latewood proportion and dry density showed a negative relationship with stem height. Radial variability trends were similar at all heights, and at both sites, revealing a rapid increase for ring width in the first 3–6 annual rings followed by a decrease towards the bark, a gradual increase for latewood proportion and no specific change for dry density. Comparisons between wood material produced during the same growth period (2005–2001) showed statistically significant differences among sampling heights in all cases except for dry density in medium sites. At the base of the stems, mean ring width and dry density were significantly (P?≤0.05) higher at good sites (3.6 mm and 0.53 g/cm³) than at medium sites (3.0 mm and 0.50 g/cm³). However, the differences between the sites are of small magnitude and therefore have limited practical impact on wood processing. The availability of such data is useful in utilising small-dimension timber of brutia pine.     

Impact of the intumescent formulation of styrene acrylic-based coatings on the fire performance of thin painted red lauan (Parashorea spp.) plywood

Intumescent material with commercial resin, such as styrene acrylic copolymer resin, has been demonstrated to be extremely effective in improving the fire performance of wooden materials used for indoor furnishing. The formulation of the coating is a key to its ability to improve flame retardance. This study investigates the enhancement for painted thin red lauan (Parashorea spp.) plywood. The ability of the material to retard flame arises due to the interactions between the four major components of intumescent formulation: (1) a binder resin (BR), styrene acrylic emulsion resin, (2) a carbonizing substance (CS), pentaerythritol (3) a foam producing substance (FPS), melamine and (4) a dehydrating agent (DA), ammonium polyphosphate. This paper compares the fire performance of the plywood when coated with resin of differing BR/CS ratios (designated as the FRS series) and FPS/DA ratios (designated as the FRD series), by means of a cone calorimeter. These intumescent formulations significantly enhanced the fire retardancy of painted plywood, exhibiting lower peak heat release rates, higher expansion of the intumescent layer and longer time to peak heat release rates (PHRR), when compared to plywood panels coated with sole binder resin. However, worse performance was presented when compared with the data for uncoated plywood panels if the intumescent was produced by equal ratio of the four components. Therefore, the formulation of the intumescent is important. Additionally, lower BR contents in the FRS series and lower FPS contents in the FRD series further enhanced flame retardancy. Advanced investigation by IR and ³¹P NMR demonstrated that lower BR and FPS content extends the survival duration of the phosphor-carbonaceous structure of chars. The findings in this study enhance the state-of-the-art understanding of the effect of the intumescent.     

Effect of quality, porosity and density on the compression properties of cork

The compression properties of cork were studied on samples obtained from cork planks of two commercial quality classes (good and poor quality), with densities ranging from 0.12–0.20g?cm^-3 and porosities from 0.5 to 22.0%. The stress-strain curves were characterized by an elastic region up to approximately 5% strain, followed by a large plateau up to 60% strain caused by the progressive buckling of cell walls, and a steep stress increase for higher strains corresponding to cell collapse. The direction of compression was a highly significant factor of variation, with cork showing higher strength for the radial compression. Density influenced compression and cork samples with higher density showed overall larger resistance to compression in the three directions. In the elastic region, an exponential model of Young’s modulus in function of cork density could be adjusted. The effect of porosity on compression was small and the stress-strain curves were similar regardless of the porosity of the samples, although there was a trend toward an overall increase of stress with porosity for higher strains. Porosity was characterised by a high variability in the anatomical features of the lenticular filling material and the presence of collapsed and thick walled lignified cells. The inclusion of a porosity parameter for the modelling of the elastic modulus did not improve the prediction obtained with density-based models. There was no significant difference in the compression properties of cork samples obtained from cork planks of good and poor quality classes.     

CT-scanning and modelling of the capillary water uptake in aspen, oak and pine

This study utilises Computer Tomography (CT-scanning) to characterize the capillary water uptake in wood specimens. CT-scanning makes it possible to study the capillary rise of water as a function of height in wood specimens after a specific exposure time. The study has also included the development of a theoretical model, which determines the capillary characteristics of wood in relation to its structure. The model developed was tested using experimental results, considering the capillary suction height and the water content change after a specific time as boundary values. A comparison between the theoretical model and the experimental results shows that not all the cells in the wood samples take part in the capillary water transport. It also appears that there is a structural resistance to capillary flow.     

Untersuchung von Buchenschnittholz (Fagus sylvatica L.) hinsichtlich der Eignung für Brettschichtholz

Beech glulam for structural purposes has to be manufactured from strength graded beech lumber. At present one can assume that such material is not available on the market: There is not only a lack of practice in strength grading of beech lumber but also a lack of clearly defined raw material to be strength graded for beech glulam. This article aims to show that beech lumber graded following the Rules of the Measurement and Inspection of Hardwood and Cypress (published by the National Hardwood Lumber Association) has a potential as raw material for beech glulam. 218 beech boards approximately complying with two different grades, an upper and a common grade, were examined in regard to visual strength grading according to DIN 4074-5 (2003). The results show that 90% of the upper grade and 50% of the common grade boards fulfil the requirements for grade LS10 in DIN 4074-5 (2003). This finally enables the manufacture of beech glulam in accordance with strength class GL28. In addition, mechanical strength grading taking into account the modulus of elasticity even enables grading of 80% of the upper and 40% of the common grade boards for GL40.     

Innovative lay-up system in plywood manufacturing process

In the traditional plywood manufacturing process, the lay-up stage absorbs approximately 24% of the total manufacturing costs. It usually requires a large amount of manpower and produces a significant amount of waste material. Therefore, the authors have developed an innovative system based on a new idea that reduces these values drastically. The solution is characterized by intensive use of flexible automation, and this breakthrough lay-up system technology is specifically discussed in relation to plywood manufacture. Since the new system was tested, it has been adopted and used by the European leader in poplar plywood manufacturing. Interesting results include productivity increases of up to 20%, a decrease in lay-up costs of approximately 19% and a consumption of area reduced about 42%. Moreover, by reducing manpower requirements, the new system generates a significant reduction in the number of problems relating to product quality and operator safety, which is certainly not a trivial question in the traditional lay-up system.     

Evolution of internal stress during drying, cooling and conditioning of rubberwood lumber

In an attempt to develop a real-time measurement technique for an internal stress perpendicular to grain in the radial direction of rubberwood lumber during drying and conditioning, a novel design of a force measuring device, consisting of a restrained half-sawn specimen and a restrained free shrinkage specimen, was constructed. The measured force was verified with a differential released strain obtained from the conventional McMillen slice technique. The device was then employed to investigate the internal stress evolution during drying and conditioning of rubberwood lumber. It was shown that the force measured using the device strongly correlates with the differential released strain. The extents of the internal stress characteristics such as the maximum tensile and compressive forces and the reciprocal of time at stress reversal obey the Arrhenius equation and the adapted equation of sorption for the temperature and humidity dependences, respectively. The results also indicate that cooling under relatively high humidity after drying improves the internal stress relaxation process during conditioning. Possible application of the technique in kiln drying of rubberwood has been demonstrated. The measured force could be used as controlling parameter for an adaptive wood drying control system taking into account real-time material response of wood during drying and conditioning.     

On the performance of a melamine–urea–formaldehyde resin for decorative paper coatings

The decorative laminates industry is a highly competitive industrial sector. To be profitable, manufacturers of impregnated papers for surface laminated MDF and particleboards need to significantly reduce their production costs. Melamine formaldehyde resin (MF) formulations are commonly used for impregnation and coating of such papers, melamine being an important, but costly raw material used in high quantities. While MF is substituted by cheaper urea formaldehyde resins (UF) in the core impregnation, for paper surface films pure MF is used. Therefore, a further reduction in cost could be achieved if a portion of the melamine in the surface film was replaced by urea. In the present contribution, recent results of technological tests on paper laminates using a novel melamine–urea–formaldehyde resin (MUF) formulation are reported and their performance is compared to traditional surfaces made from MF.     

Carbonization of hot-pressed ARBOFORM ®-mixtures

Porous carbon materials have a wide range of technical applications due to their properties including low density potential, mechanical capacity, resistance to heat and corrosion as well as electric conductivity. Organic materials like phenolic resins or polyacrylnitrile are typically employed as green body for carbon ceramics. However, wood and especially wood-based composites are also suitable as well as hot-pressed ARBOFORM^®-powder mixtures from lignin, wood meal and natural additives, which varied with regard to their lignin content as well as partly regarding their additive rates. The objective of the present study was to investigate the influence of some admixed additives of a commercially available wood based composite on carbonization results. The experiment was performed due to its more homogenous material properties in comparison to solid wood. Another aspect was the possibility of forming mixtures of ARBOFORM^® by extrusion or injection moulding. Such production processes are already state of the technology and therefore it could be possible to produce complex carbon- and ceramic templates which are difficult to realize by conventional processing methods. Concerning the thermoplastic process step of ARBOFORM^® there are further advantages compared with the used wood based panels. The samples were pyrolyzed in a nitrogen atmosphere at a temperature of up to 900 °C. Regarding the absence of cracks, best results were achieved with blend P60 which had a higher content of wood particles. Addition of only 10% of phenolic resin significantly counteracted density reduction.     

Untersuchungen zum Einfluss des Plattenaufbaus auf ausgewählte Eigenschaften von Massivholzplatten

The coefficient of thermal conductivity, the equilibrium moisture content, the in-plane swelling and the water vapour resistance of laboratory-produced three-layer solid wood panels of Norway spruce wood were tested. The coefficient of thermal conductivity is in the range of 0.09–0.11 W/m·K in normal climate. The voids in the middle layer (slots, spaces between the lamellas) cause a slight decrease of the coefficient of thermal conductivity. The orientation of the growth rings has an effect on the thermal conductivity as well. The water vapour resistance is affected by the orientation of the growth rings in the layers and the voids in the middle layer. The equilibrium moisture content above a relative humidity of 35% is slightly below the one of solid spruce wood. The equilibrium moisture content of solid wood panels with a middle layer of wood-based material is smaller because of its lower equilibrium moisture content compared with solid wood.     

Reliability of proof-loaded Norway spruce

Strength grading of structural timber is a prerequisite for the use of timber in load-bearing constructions. The grading methods used in production today are mainly based on estimation of the modulus of elasticity (MOE) determined from measurements of either flatwise bending stiffness or resonant vibrations. By using proof-loading techniques, the yield can be increased and the reliability of the graded material can be improved. Unfortunately, this technique can cause damage to some of the graded material. This paper deals with the quantification and severity of damage caused by proof-loading of Norway spruce (Picea abies) timber. A total of 410 specimens were loaded in cyclic bending with increasing load level in each cycle until failure. The maximum loads during the tests were compared to the failure loads of a reference sample. If the failure load was lower than the maximum load, the specimen was assumed to have been damaged in the previous load-cycle and was defined as a rogue. The technique used is similar to the technique used for example in Australia. The results obtained fit well with the results obtained from Australian species. Examination of the MOE indicates no damage in the specimens at stress levels below 75% of the strength. Damage is in this case defined as a decrease in the MOE. Regarding Norway spruce grown in Sweden it can be concluded that the problem of damage due to proof-loading is small for timber graded to strength classes C24 or C30. For both classes the number of rogues can be expected to be less than 5%. For timber graded to higher strength classes the problem of damage due to proof-loading will increase.     

Untersuchungen zum Kegelstirnplanfräsen und Stirnplanfräsen am Institut für Werkzeugmaschinen der Universität Stuttgart

Slab milling with a conical shaped milling tool and slab milling with a face milling tool are wood machining techniques which meet the current requirements of wood machining and processing (e.g. changing batch sizes, flexible machines and equipment). That is why the Institute for Machine Tools at University of Stuttgart has already conducted comprehensive basic research in this field (Heisel 1997). Research on slab milling with a face milling tool was especially promoted as an alternative to slab milling with a peripheral milling tool (also known as planing) due to its low noise emission and low energy consumption. Amongst others, slab milling with a face milling tool as pre-milling procedure when calibrating wood-based panel products was examined under technical and economic aspects. The results showed higher service life and continuously better surfaces when choosing the right geometry of the cutting tools as compared to conventional slab milling with a peripheral milling tool. Notwithstanding the high costs, diamond cutting edges are more cost-effective than carbide insert tips due to their longer service life (Heisel 2004).     

Eigenschaften von extrudierten Holz-Kunststoff-Werkstoffen auf Basis von Refiner-(TMP-)Fasern und Hanffasern

At present, wood particles (wood flour) with a low aspect ratio are mostly used as fillers in wood-plastic composites (WPC). Reinforcement of WPC and improved strength properties may be achieved by using real wood fibres with a high aspect ratio. WPC based on 70% (wt.) refiner (TMP) wood fibres and mechanically processed hemp fibres were extruded in a two-step process. Eleven compounds based on the two natural fibre types were prepared using a thermokinetic mixer and extruded in a conical, counter-rotating twin-screw extruder. Additional formulation components were polypropylene fibres, maleic anhydride-modified polypropylene (MAPP) and lubricant. It was determined that compounding in a thermokinetic mixer is a useful step for processing of WPC with refiner and hemp fibres as little fibre damage occurred. However, during extrusion, both natural fibre types were severely shortened due to strong shear forces, and homogeneous dispersion of fibres in the matrix was not achieved. WPC based on hemp fibres displayed the best strength properties of the formulations tested. Current extruder screw and die configurations need to be modified to achieve improved fibre reinforcement and to create new, structurally demanding applications for WPC. Using dynamic mechanical analysis, fibre-matrix adhesion of WPC was investigated, and activation energies for glass transition of selected formulations were calculated. Activation energy for formulations containing MAPP was higher than for WPC without MAPP. This indicates that better fibre-matrix adhesion was achieved in formulations with MAPP.     

Influence of different climatic conditions on the roughness of uncoated medium density fiberboards (MDF)

The surface roughness is primarily a function of the raw material properties, but other factors like type and amount of resin, press cycle, sanding and moisture content of the boards may also affect the roughness and other surface properties. In this study the effect of the equilibrium moisture content on medium density fiberboards (MDF) surfaces was evaluated using different raw materials in the surface layers as well as different binders. The statistical analysis confirmed that the relationship between equilibrium moisture content and average roughness is a complex function of interactions between many variables.     

Gas pressure measurements during continuous hot pressing of particleboard

Knowledge about the development of the internal gas pressure during hot pressing of wood-based composites is important for the optimization of panel properties and production speed. The gas pressure heavily affects the thermodynamic conditions inside the wood furnish mat, and a too high maximum value at press opening might cause an impairment of the panel properties. In this paper, gas pressure and temperature measurements inside a particle mat while passing through a continuous hot press are presented for the first time. The measurements were performed with a transportable system, consisting of a steel tube attached to a miniature pressure transducer and a data logger. The particleboards had a target thickness of mainly 16 mm, but also of 28 mm and 38 mm, respectively. The measurements show a distinct horizontal gas pressure distribution in both directions, in production direction and across the mat’s width. In contrast, cross-sectional gas pressure gradients were only visible inside the panels after leaving the press. By comparing the gas pressure curves measured for particleboard with those for medium density fiberboard (MDF), characteristic differences became evident. Overall, the gas pressure is higher in MDF compared to particleboard. Finally, a comparison between the gas pressure levels measured for three different panel thicknesses showed a clear relation between panel thickness and gas pressure, with a decreasing panel thickness resulting in an increase in gas pressure. The results of this paper will contribute to our understanding about the events inside wood furnish mats during continuous hot pressing.     

Modeling the effect of length on yield of sawn timber grades in Norway spruce (Picea abies (L.) Karst.)

The aim of the study was to model and analyse the effect of length on grade yield of timber from different stem parts in Picea abies, and to use the models to simulate the cost of reduced grade yield due to increased length. The boards were simulated having lengths ranging from 20 to 60 dm starting at stump level, 4 m above stump level and 8 m above stump level, respectively. Logistic regression models showed that length had a significant effect on grade yield, and this length effect was stronger in strength grading according to INSTA 142 (IN) compared to appearance grading according to Nordic Timber (NT). The length effect was most pronounced in butt logs, and somewhat greater in middle logs compared to top logs. Also a smaller length effect in inner boards compared to boards farther from the pith was found for IN-grading. The cost of the decrease in grade yield with increasing length will depend on the assumptions about the price gap between the grades. Current market prices in both grading rules gave a decrease in value of the sawn timber in stock by about 6% with an increase in the log length from 45 to 60 dm. In addition, a decrease in yield of timber in longer logs will amplify this effect, while a higher efficiency in the production process will diminish it.     

Mechanical properties of wood treated with PF-pyrolytic oil resins

Jack pine and sugar maple wood samples were treated in a two-step process that involved first a copper chloride or a copper chloride-sodium borate mixture and then a phenol-formaldehyde resin containing a certain percentage of softwood bark pyrolytic oil. Various controls were also prepared for comparison. The modulus of rupture (MOR) of jack pine samples was generally negatively affected by the treatment, the observed values being lower than those of the controls. These values were statistically lower or equal to those of untreated samples. On the other hand, the modulus of elasticity (MOE) of treated jack pine samples was not found to be statistically different from that of the untreated wood. Mechanical properties behaved in a similar way for sugar maple wood. Unlike the other treatments, copper chloride–sodium borate and the resin containing 85% of pyrolytic oil as phenol substitute appeared to slightly improve the mechanical properties of both wood species even if not significantly so. Treatment with PF-pyrolytic oil resin resulted in similar or slightly better mechanical properties when compared to CCA-treated wood. The amount of treating water soluble salts retained in samples after the first treatment had a significant impact on MOR of both wood species and on MOE of sugar maple.     

Prehydrolysis of xylan in culm of Sasa kurilensis with dilute sulphuric acid

To prepare a substrate for microbial conversion of xylose into xylitol, the culm of Sasa kurilensis was hydrolysed with dilute sulphuric acid. A fermentable substrate with a relatively high xylose concentration (21.9?g?L^?1) was obtained by hydrolysis with 2% sulphuric acid with a liquid to solid ratio of 10?:?1 at 121°C for 1?h. During hydrolysis at elevated temperatures, some undesirable byproducts were also generated, such as degradation products of solubilized sugars and lignin, which are potential inhibitors of microbial metabolism. These compounds were successfully removed from the hydrolysate by treatment with a commercially available activated charcoal (30?g?L^?1 dose).