Reach Equilibrium Moisture Content Research Articles

Prediction Distribution Model of Moisture Content in Laminated Wood Components.

Shrinkage cracks are some of the most common defects in timber structures obtained from woods with an uneven distribution of moisture content and are subject to external dynamic environmental changes. To accurately predict the changes in the moisture content of wood components at any time and position, this study first applied the principles of food drying and established a moisture field model for laminated wood based on the analogy between heat and humidity transfer. A model for predicting the moisture content of wood that considers time and spatial distribution was then proposed. Second, by collecting relevant experimental data and establishing a finite element analysis model, three moisture absorption conditions (0-9.95%, 0-13.65%, and 0-17.91%) and four desorption conditions (34-5.5%, 28-8.3%, 31-11.8%, and 25.5-15.9%) were analyzed. In the moisture absorption comparison, the time needed to reach 95% equilibrium moisture content was 2.43 days, 4.07 days, and 6.32 days. The rate at which the internal components reached equilibrium moisture content exceeded 10 days. The temporal and spatial distribution of wood moisture content revealed the correctness of the proposed wood moisture field model. Finally, the moisture content prediction model was applied in the order of characteristic equation solutions, moisture content gradient difference, and laminated wood size. The results revealed that the established humidity field model can predict the wood moisture content and how it changes over time and in space. Notably, 1-2 orders for the solution of the characteristic equation are recommended when applying the prediction model. The greater the difference in moisture content, the faster the equilibrium moisture content is reached. The moisture content varies greatly based on the component size and position. Notably, the influence of moisture gradient and wood size on the average wood moisture content cannot be ignored.

Effects of ultrasonic power on drying kinetics and product quality of licorice extract during ultrasound-assisted vacuum drying.

Licorice extract is an important raw material for food additives and medicine. The quality of licorice extract is dictated by the drying process. The commonly used drying methods of licorice extract are not efficient in obtaining high-quality products so alternative techniques need to be developed and researched. In this study, ultrasound-assisted vacuum drying (UAVD) was first utilized to improve drying efficiency and produce a higher-quality product. The changes in water mobility of licorice extract during drying were characterized using low-field nuclear magnetic resonance. In addition, the effects of ultrasonic power on the drying dynamics, the contents of liquiritin and glycyrrhizic acid, the antioxidant capacity and the microstructure formation of licorice extract during the whole drying process were investigated. The drying times for licorice extract to reach equilibrium moisture content were reduced by 9.09-69.70% with UAVD at 40-200 W compared with that without ultrasonic treatment (0 W). Moreover, the proportions of bound water and semi-bound water in fresh concentrate were 3.75% and 96.25%. It was also found that high ultrasonic power promoted the flow of water and the formation of porous structure in licorice extract, which led to the improvement of drying efficiency. The contents of liquiritin (2.444%) and glycyrrhizic acid (6.514%) were retained to a large degree in the dried product at an ultrasonic power of 80 W. The DPPH inhibition rate of UAVD samples with different ultrasonic powers ranged from 84.07 ± 0.46% to 90.65 ± 0.22%. UAVD has the advantages of high efficiency and low energy consumption, which may be an alternative technology for vacuum drying widely used in industry. © 2024 Society of Chemical Industry.

Comparison of the dried properties of Ganoderma lucidum produced by the convective dryer and infrared dryer

Ganoderma lucidum is a promising medicine with a high amount of antioxidants and calcium. The selection of appropriate drying process methods in food science has a chief role to reach the best final characteristics. This study aimed to investigate the effects of air velocity and temperature in the convective dryer, sample distance, and infrared power in infrared dryers on the drying kinetics and quality of Ganoderma lucidum slices. In addition, Response Surface Methodology based on central composition design was used to optimize and analyze drying conditions. The ranges of temperature and air velocity were 40–60 °C and 0.5–1.5 m/s, respectively in the convective drying process while the range of distance and infrared power was 4–16 cm and 500–1500 W, respectively in the infrared drying process. It is worth mentioning that antioxidant and calcium contents were greatly enhanced during the drying procedures. Moreover, the values of the total color difference ranged between 8.21 and 19.66 for the convective dryer and 8.14 and 28.85 for the infrared dryer. A kinetic study indicated that dried samples by the infrared dryer could rapidly reach equilibrium moisture content due to exposure to IR radiation. Consequently, the results indicated that the infrared dryer has better performance than the convective dryer regarding drying time, energy consumption, and amount of calcium and antioxidant.

Drying Behavior of Moringa Oleifera Leaves using Tray Dryer

Moringa oleifera leaves have been dried in a tray drier to investigate the drying behaviors of Moringa oleifera leaves at three different temperatures for their moisture content, color, iron and protein content, as well as total phenolic content. Three levels of temperatures were chosen varying from 50, 60 and 70 °C in this study. Drying time reduced significantly with the rise in temperature. The final moisture content of dried leaves at 50, 60 and 70 °C was 4.89, 4.79, and 4.59 % and reached equilibrium moisture content at 4, 2, and 1.5 hours. For the water activity, all the dried leaves give a low amount of water activity from 0.0912 to 0.1838 at 70 - 50 °C where the higher the temperature the lower the water activity. This indicates that the lower the temperature, the slower the drying time required to decrease moisture content to below 5 % and a smaller amount of water activity. This ability to preserve its taste and nourishment. For the color changes, the value for greenness (-a) has no significant difference but notable differences were detected between the color parameters of fresh and dried leaves for whiteness L value and yellowness b. This shows that drying under a tray dryer has the same color as the fresh M. oleifera leaves. There was no notable difference in the value for protein but a significant difference (P<0.05) in the value for iron contents of the fresh and dried leaves. The total phenolic content (TPC) obtained from this study was 46.97 - 55.78 mg GAE/g FW for drying at 50 to 70 °C. Results from this study discover a great option for large-scale drying using method.

Quantifying Forest Litter Fuel Moisture Content with Terrestrial Laser Scanning

Electromagnetic radiation at 1550 nm is highly absorbed by water and offers a novel way to collect fuel moisture data, along with 3D structures of wildland fuels/vegetation, using lidar. Two terrestrial laser scanning (TLS) units (FARO s350 (phase shift, PS) and RIEGL vz-2000 (time of flight, TOF)) were assessed in a series of laboratory experiments to determine if lidar can be used to estimate the moisture content of dead forest litter. Samples consisted of two control materials, the angle and position of which could be manipulated (pine boards and cheesecloth), and four single-species forest litter types (Douglas-fir needles, ponderosa pine needles, longleaf pine needles, and southern red oak leaves). Sixteen sample trays of each material were soaked overnight, then allowed to air dry with scanning taking place at 1 h, 2 h, 4 h, 8 h, 12 h, and then in 12 h increments until the samples reached equilibrium moisture content with the ambient relative humidity. The samples were then oven-dried for a final scanning and weighing. The spectral reflectance values of each material were also recorded over the same drying intervals using a field spectrometer. There was a strong correlation between the intensity and standard deviation of intensity per sample tray and the moisture content of the dead leaf litter. A multiple linear regression model with a break at 100% gravimetric moisture content produced the best model with R2 values as high as 0.97. This strong relationship was observed with both the TOF and PS lidar units. At fuel moisture contents greater than 100% gravimetric water content, the correlation between the pulse intensity values recorded by both scanners and the fuel moisture content was the strongest. The relationship deteriorated with distance, with the TOF scanner maintaining a stronger relationship at distance than the PS scanner. Our results demonstrate that lidar can be used to detect and quantify fuel moisture across a range of forest litter types. Based on our findings, lidar may be used to quantify fuel moisture levels in near real-time and could be used to create spatial maps of wildland fuel moisture content.

Moisture content changes of beech and ash elements during two years in room conditions

The subject of this paper is the analysis of moisture content (MC) changes of beech and ash wood during two years in room conditions (heating during winter; no air conditioning during summer). The registered MC changes are primarily the result of changes in relative humidity of the air (measured by capacitive probes). The average relative humidity of the air in the interior is lower today than in the past, as also shown in this experiment (the average relative humidity of air during two years was 44%). The lowest wood MC was reached on very cold winter days when the heating was on even during the night - between 5% and 6%, and the highest one at the beginning of June: 10.4-10.9%. As expected, the wood did not reach equilibrium moisture content - during winter, MC is by about 1% higher, and in summer it is lower by up to 2.5% than the equilibrium. The recommendation that the sawn timber from which the interior products will be made should be dried at 7-8% MC was confirmed.

Propriedades termodinâmicas da polpa de cajá (Spondias mombin L.)

Spondias mombin L. é um fruto nativo do Brasil, há uma variação da espécie nativa no Cerrado. Seus frutos são utilizados na produção de alimentos para fabricação de geléias, sorvetes e sucos e as folhas são utilizadas na medicina popular para tratar doenças inflamatórias. Objetivou-se analisar o comportamento termodinâmico e as propriedades da polpa de cajá em pó em diferentes temperaturas durante o processo de dessorção. A análise foi realizada pelo método dinâmico-gravimétrico. Os frutos de cajá com atividade de água entre 16,96 e 57,43 foram usados para as análises termodinâmicas. A dessorção da camada fina do fruto foi observada em diferentes temperaturas (10, 20, 30 e 40° C) e níveis de atividade da água, variando de 0,17 a 0,57, até o produto chegar ao teor de umidade de equilíbrio na condição de ar especificada. As propriedades termodinâmicas da polpa de cajá foram afetadas pelo teor de temperatura e umidade. A teoria isocinética pode ser comprovada para o processo de dessorção e esta é controlada pela entalpia. A dessorção de água em frutos de cajá é um processo não espontâneo.

The law and mechanism of dynamic methane diffusion from coal particles under different moisture content

As a theoretical basis, methane diffusion from coal particles can be used to determine the coalbed gas content, gas desorption index by drill cuttings of coal, evaluation parameters of coal gas mining, and the gas outburst prediction. Moisture content is one of the significant factors influencing the diffusion law of gas-bearing coal particles. In this paper, three deformed coal samples with diverse metamorphic degrees, taken from three different coal mines with coal and gas outburst hazard, were investigated through the self-made devices. The variation law of diffusion flux, diffusion coefficient, and diffusion speed with moisture content was experimentally studied. The results show that diffusion flux, diffusion speed, and diffusion coefficients of high-, medium-, and low-rank coal samples decrease significantly with the increasing moisture content until they reach equilibrium moisture content. The diffusion coefficient of dry coal particles is 3–5 times larger than that of coal particles with equilibrium moisture at the same metamorphic degree. The diffusion coefficient of coal samples at different ranks decreases with time and ranges from 1.58E-08 to 3.03E-07 cm2/s. Based on gas migration theory in porous media and experimental results, the influence mechanism of moisture on gas diffusion rules was discussed.

An overview of fish drying kinetics

PurposeFishes are important sources of good and high-quality protein in developing countries. Spoilage and keeping quality of fish especially in the tropics is temperature dependence as high temperature and relative humidity accelerate the process of spoilage and fish keeping quality. Fish dehydration removed moisture and extended the shelf life of dried fish. Drying involves removal of moisture from fish as a result of heat and mass transfer done under controlled conditions. This study delves into various drying techniques and drying kinetics of fish.Design/methodology/approachThe review examines fish drying kinetics and the various drying models applicable to fish drying.FindingsThis review showed that moisture content and colour of dried fish are affected by time and power level. It was also found that the moisture content of the dried fish varied according to the drying method used. Also, as drying power and drying rate varied inversely with drying time. Eight different thin layer drying models were examined for evaluation of drying data for all the experimental conditions involving fish drying. It was found that the quality of the dried fish decreased with drying. Higher values of effective moisture diffusivity have been found to increase moisture velocity within fish samples which improve removal of moisture to reach equilibrium moisture content at specified relative humidity. However, based on this, effective moisture diffusivity could be a useful parameter to design an effective drying method in terms of time, energy consumption and cost to prolong the storage life of dried fish samples. Drying kinetics and different drying models were considered and explained. The use of these models was considered to be important in choosing appropriate drying conditions for effective drying and to get good quality dried fish samples.Research limitations/implicationsThe review considers few available literatures on the subject matter.Practical implicationsThe review explores the possibility of creating more awareness for more in-depth research on fish drying kinetics and their usefulness in fish preservation.Originality/valueThis outcome of this study is important to researchers, policymakers and regulatory agencies in developing countries on fish preservation.

Hydration kinetics of little millet and proso millet grains: effect of soaking temperature.

Hydration characteristics of little millet (Panicum sumatrense) and proso millet (Panicum miliaceum) were studied at different soaking temperatures (30, 40, 50, 60 and 70°C) and fitted into hydration models. From the initial moisture contents of 11.02 (d.b.) and 10.45% (d.b), little millet and proso millet grains attained the equilibrium moisture content of 38-50.17% (d.b) and 39.11-47.15% (d.b.), respectively. Little millet took 18.5h to reach equilibrium moisture content at soaking temperature of 30°C and 3.5h at 70°C. For proso millet, it took 4h at 70°C and 19h at 30°C. The data of moisture content with time fitted to Lewis, Page, modified Page and Peleg models shown higher coefficient of determination values ranging from 0.92 to 0.99. Among the models, the Peleg model is more suitable for the little millet grains and both Page and Peleg models are more suitable for the proso millet grains, to represent the hydration kinetics in the soak water temperature range of 30-70°C. The dependency of the coefficients of the hydration models with temperature of soaking was found to be linear for both little and proso millets with coefficient of determination values ranging from 0.88 to 0.97.

THERMODYNAMIC PROPERTIES OF SORPTION OF RICE IN THE HUSK

ABSTRACT This study aimed to determine the thermodynamic properties of sorption processes (desorption and adsorption) of rice in the husk, cv. Urucuia. A static-gravimetric method was used to reach equilibrium moisture content at different temperatures (10, 20, 30, 40, and 50 °C ± 1°C) and relative humidity levels (10, 30, 50, 70, and 90 % ± 2%). A decrease in moisture content led to an increment of the integral isosteric heat of sorption, indicating a higher demand for energy to remove moisture from the product. Differential entropy of sorption decreased along with a moisture content increment, with higher values for desorption. This indicates a higher mobility of water molecules during desorption if compared to adsorption. Gibbs free energy decreased with increasing temperature in both processes, with positive values for desorption (endothermic process), and negative for adsorption (exothermic process). The enthalpy-entropy compensation theory is valid for both sorption phenomena (desorption and adsorption) of rice in the husk, being both processes enthalpy controlled.

Study on dimensional stabilization of 12,500-year-old waterlogged subfossil Scots pine wood from the Koźmin Las site, Poland

Abstract The study examines the efficiency of selected conservation treatments proposed for dimensional stabilization of 12,500-year-old waterlogged subfossil Scots pine (Pinus sylvestris L.) tree trunks found at the Koźmin Las site, Poland. The research was done on 198 samples drawn from various parts of the same trunk. Experimental material was characterized on the basis of annual ring width, percentage of latewood, maximum moisture content, density at maximum moisture content, basic density, and wood porosity. Waterlogged wood samples were pre-treated with aqueous solutions of polyethylene glycol (PEG) 300, mixtures of PEG 300 and PEG 4000, a mixture of lactitol and trehalose or a mixture of mannitol and trehalose (nine variants of impregnation) and then freeze-dried or air-dried. Dimensional changes in the wood samples were measured after seasoning to reach equilibrium moisture content at 50% relative humidity and 20 °C. In the majority of the tested conservation treatments, tangential and radial shrinkages or tangential and radial swelling of wood did not exceed 1%. However, differences in dimensional changes depended on the conservation method used and sampling location. Regardless of the state of wood preservation and macroscopic structure features, the best dimensional stability, evaluated on the basis of average anti-shrink efficiency indices, was observed in wood pre-treated with aqueous solutions of 10% PEG 300 + 5% PEG 4000, 10% PEG 300 + 10% PEG 4000 or 10% lactitol/trehalose mixture, and then freeze-dried.

Assessing the structural stability of gluten-free snacks with different dietary fiber contents from adsorption isotherms

Gluten-free snacks (GFS) with high dietary fiber and relatively low-fat contents were made by combining unripe plantain:chickpea:maize flours in the following proportions 50:30:0; 10:60:30; and 33:33:34, respectively. The adsorption isotherms built from equilibrium moisture content data of the snacks exposed to water activity (aw = 0.10–0.90) at different temperatures (20, 25, 30, 35, 40, or 45 °C) environments, using a dynamic vapor sorption analyzer, were compared to those of a commercial snack control with high-fat content (33.85 g/100 g). All the snacks reached equilibrium moisture content within 5 h for most values of aw, and the experimental data were fitted with the Guggenheim-Anderson-de Boer model. The monolayer moisture content and the critical water activity (linked to glassy-to-rubbery phase transitions) of the GFS were significantly lower than that of the commercial snack, indicative that GFS underwent structural weakening under humidity stress. Also, the GFS showed a crossover in the isosteric heat of adsorption (estimated with Clausius-Clayperon equation) at approx. 11% relative moisture content that could be related to the formation of complex multilayered structures. The differences in the adsorption characteristics between GFS and commercial snack can be attributed to the chemical composition, mainly to the fat content.

ARTIFICIAL NEURAL NETWORKS AS A NEW TOOL FOR ASSESSING AND MONITORING WOOD MOISTURE CONTENT

ABSTRACT Drying of wood is necessary for its use and moisture control is important during this process. The aim of this study was to use artificial neural networks to evaluate and monitor the wood moisture content during drying. Wood samples of 2 × 2 × 4 cm were taken at 1.3 m above the ground, outside of radial direction, from seven 2-year-old materials and three 7-year-old materials. These samples were saturated and drying was evaluated until the equilibrium moisture content, then, the artificial neural networks were created. The materials with higher initial moisture reached equilibrium moisture content faster due to its higher drying rate. The basic density of all wood materials was inversely proportional at the beginning and directly proportional to the moisture at the end of drying. All artificial neural networks used in this work showed high accuracy to estimate the moisture, however, the neural network based on the basic density and drying days was the best. Therefore, artificial neural networks can be used to control the moisture content of wood during drying.

Effects of Pre-Freezing Prior to Drying upon Some Physical and Mechanical Properties of Eucalyptus urophylla × Eucalyptus grandis Wood

To investigate the effect of pre-freezing treatment on the shrinkage properties and discoloration of Eucalyptus urophylla × Eucalyptus grandis wood, E. urophylla × E. grandis wood samples were treated by pre-freezing at -20 and -40 °C for 72 h and then dried to reach equilibrium moisture content at 12% and 8%, respectively. Color changes were measured by colorimeter and evaluated by diffuse reflectance visible (DRV) spectrometry; mechanical properties were also tested. The results showed that the shrinkage of Eucalyptus wood samples decreased after being pre-frozen, and the overall color change ΔE* increased by 6.11 when the treatment temperature changed from minus 20 to -40 °C. Absorption (ΔK/S) spectra in the range of 450 to 740 nm of the treatment samples exhibited flat-lined, which suggests that the color of wood stabilizes after being pre-frozen and dried. The tensile, compression and bending strengths decreased 4.74, 6.05, 1.18 after pre-freezing treatment at -40 °C, respectively. Pre-freezing treatment at -20 °C is better than that at -40 °C for improving the drying properties of E. urophylla × E. grandis wood.

Sorption behaviour of papayas as affected by compositional and structural alterations from osmotic pretreatment and drying

Moisture sorption dynamics and isotherms of fresh, osmotically-pretreated and dried papayas at temperatures of 30, 50 and 70°C and water activity in the range of 0.113–0.907 were investigated. Chemical composition as well as volume, density, porosity and microstructure of the fruits were analysed. Results showed that the time required to reach equilibrium moisture content was mainly dependent on temperature, water activity level and processing method. The difference in moisture sorption characteristics between fresh, pretreated and dried papayas was attributed to (i) changes in the contents of sugars after osmotic dehydration and (ii) structural modifications caused by drying, which were corroborated by examination of micrographs. The differences in sorption were also proven by the selected isotherm models. The modified Halsey equation described the sorption behaviour of the pretreated and dried papayas, whereas the untreated, fresh samples were better predicted by the modified Oswin equation. Further indication that osmotic pretreatment and drying influenced the interaction between the sorption sites and water molecules was imparted by the values of isosteric heat of sorption (Qst) for fresh and dried papayas at different temperatures.

CREEP OF SMALL DIAMETER TIMBER POLES

It has become necessary to encourage the use of small diameter timber poles (plantationthinnings) as building timber particularly in roof construction, as the supply of betterknown indigenous species can no longer meet the increasing demand for constructiontimber. Eucalyptus and Pinus species were introduced to Sri Lanka some years ago and atpresent there exists a large area under their plantation. While the larger diameter trees areused in pole form for transmission poles or are processed for furniture, the thinnings havehad little use. Preliminary studies were carried out to assess the feasibility of using thethinnings as roof timber. The mechanical properties were found to be adequate. Boththese species however need to be preservative treated to increase their durability. Borondiffusion was considered a cost effective method of treatment provided the poles are usedwhile still green. Previous studies have shown that the poles removed from a Boronpreservative tank took 3 to 4 months to reach equilibrium moisture content. Thus theymust be allowed to dry out under load.The limiting of deflection often controls the design of seasoned timber beams. It is thusexpected that limiting deflection, will be more the controlling design requirement for thegreen poles drying out under load. The magnitude of long term or creep deflection thatoccurs as the poles dry out under load is thus significant and needs to be determined.This paper describes an investigation into the creep behaviour of initially green smalldiameter timber poles drying out under load. The magnitude of a factor that can be appliedto instantaneous elastic deformation to evaluate long term deformation is determinedexperimentally for timber poles of Eucalyptus and Pinus species of different diametersdrying out under a range of bending stresses.

Optimization of the Effect of Process Parameters and Study of Quality Characteristics of Osmotic Dehydrated Amla Slices

The osmotic dehydration technique not only enables the storage of the fruits for a longer period, but also preserves flavour, nutritional characteristics and prevents microbial spoilage. Osmotic Dehydration is done by immersing Vegetable & Fruits, whether in pieces or whole, in salt or sugar aqueous solution of high osmotic pressure. The amla (Phyllanthus emblica) is an effective source of Vitamin C. The ascorbic acid (Vitamin C) content in the amla fruit is one of the highest contents of all plants. The amla plant has been used in Indian medicine for years. In Ayurvedic medicine, the amla plant is used to treat minor hemorrhage and to help foster cardiovascular health. The study conducted for Amla slices during osmotic dehydration followed by tray drying and the influence of process variables on the quality characteristics. The samples were osmodehydrated at in combination of sugar (25- 60°Brix) and salt (5%, 7.5% and 10%) solution at temperature of 30°C in 4:1 and 8:1 ratio. The treated sample slices were spread on stainless steel trays of the tray dryer and they were dried in tray dryer at temperature 50 0 C. The samples were weighed at an interval of 30 minutes. The sample took around 2 to 3 hours depending on the drying temperature to reach equilibrium moisture content. It was observed that the weight reduction, solid gain and weight loss increased with increase of the parameters like time, concentration of the sugar solution and ratio of the solution to sample. The quality parameters such as reducing sugars and ash content were determined.

Drying Characteristics of a Microalgae Consortium Developed for Biofuels Production

Microalgae are a promising renewable biomass feedstock that can be used to produce a wide range of bioproducts and biofuels. Drying is a critical step in algal biomass production as it improves shelf life, facilitates easier transport and storage, and enhances the extraction efficiency of lipids and other value-added compounds. This article investigated the thin-layer drying characteristics of a robust consortium of green algae consisting of Scenedesmus bijuga, Chlamydomonas globosa, and Chlorella minutissima grown in an open raceway pond. The microalgae consortium samples were harvested with 20% solids content using a centrifuge and were used for conducting thin-layer drying experiments in a convective oven. The change in moisture with time at each selected drying temperature (30°C, 50°C, 70°C, and 90°C) was recorded until the sample reached equilibrium moisture content. A typical drying curve for a microalgae consortium indicated that microalgae drying occurred at a falling rate, and the rate of drying was limited by diffusion. Three thin-layer drying models (Newton, Page, and Henderson-Pabis) were used to fit the microalgae drying data. The Page model fitted well with the drying data with high R2 (0.99) and low RMSE (0.02) values. Effective diffusivity of moisture from the microalgae was determined using the Henderson-Pabis model and increased from 1.94 × 10-10 to 1.74 × 10-9 m2 s-1 with increase in drying temperature from 30°C to 90°C. The low value of moisture diffusion rate from the microalgae samples may be attributed to shrinkage and case hardening of algae cells at the top drying surface. Both the effective diffusivity and the drying constant had significant dependence on drying temperature and were related with Arrhenius-type relationships. Biochemical compositions and fuel characteristics of the dried microalgae consortium were determined, and the dried microalgae can be an attractive feedstock for biofuel production.

Visual identification, physical properties, ash composition, and water diffusion of wetwood inGmelina arborea

Wetwood is commonly reported in temperate species but not so in tropical species. In an old Gmelina arborea Roxb. plantation, wetwood was identified by a darker colour compared with the rest of heartwood; by a higher moisture content (average 182%); and a lower specific gravity (0.34, compared with 0.38 for sapwood and heartwood). Tangential shrinkage was 3.7%, which was significantly higher than that of heartwood and sapwood. Radial shrinkage was not significantly different between wetwood and sapwood, but it was significantly greater (2.6%) in wetwood than in heartwood (1.8%). Wetwood had a significantly higher pH than normal wood, but ash composition was similar to that of normal wood, with the exception of the amounts of iron and potassium. Wetwood and sapwood were less decay resistant than heartwood. Wetwood required less time than heartwood to reach equilibrium moisture content, but more time than sapwood. The tangential and longitudinal diffusion coefficients of wetwood were significantly higher than those of heartwood and lower than those of sapwood. In the radial direction sapwood showed a faster drying rate than wetwood but there was no significant difference between wetwood and heartwood.