Wood Modification and Wood Preservation
Yaser Hamzavi; danial harandi; Fathollah Niazi; Seyyed Mohsen Haji Seyyed Javadi
Abstract
Background and objectives: Painting on wood became popular in Iran during the Safavid period and reached its peak during the Zand and Qajar periods. The art of painting and writing inscriptions on wood as one of the unique arrays in Iran has been forgotten and their technical and pathological studies ...
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Background and objectives: Painting on wood became popular in Iran during the Safavid period and reached its peak during the Zand and Qajar periods. The art of painting and writing inscriptions on wood as one of the unique arrays in Iran has been forgotten and their technical and pathological studies will greatly help to preserve and perpetuate such works. Preservation of wood in historical buildings, where color arrays are also applied, is a complex task. The challenge of this work is related to the multiple material characteristics of the work, the type of interventions and the selection of protective chemicals that should be considered in these works. In fact, by fully understanding the work, it is possible to provide a protection solution for it. The purpose of this article is to know the materials, structure and damage of the different layers of the historical headstones of the Taqvi House in Gorgan.Methodology: The wooden lion heads of the Taqvi House in Gorgan, which have written inscriptions along with plant motifs and frames, are the study samples of the current research. The type and amount of the sample was chosen according to the existing uncertainties as well as the test method. In total, four wood samples and four paint samples were prepared. For the technical study of these works, transmission microscope, Dino-Lite plus digital microscope, scanning electron microscope (SEM) equipped with EDS detector were used. Also, under standard laboratory conditions, mushroom cultivation and wood acidity were measured.Results: The black spots in the examination with a digital microscope indicate the presence and growth of biological factors on the surface of wood, which were sampled in a part of them to cultivate and identify the fungi. Initial observations with a digital microscope indicate the destruction of wood components caused by biological factors and the reduction of wood strength and cohesion. In the first investigation, according to the cross-sections of all the samples (three samples), it was found that the samples are broad-leaved woods. The vessels are evenly distributed. In the tangential section, single-celled and multi-celled wood rays can be seen, the width of which reaches about 25 cells. The size of the vessels is almost the same and of a homogeneous and scattered type of vessel. In this sample, two to four vessels are stuck together. The average size of the vessels was measured to be 59 micrometers. Also, the frequency of vessels per square millimeter was calculated to be 130 vessels per millimeter on average. In two samples 2021.G.T.3 and 2021.G.T.8, the vessels are heterogeneous, separated and their cross section is relatively round. Heterogeneous holes and part of the aperture can be seen and some of them are tiled. The diameter of the vessels is specific from spring and summer wood. In the tangential section, single-celled or multi-celled wood rays are observed. In the continuation of the studies, the study samples were examined with a scanning electron microscope with different magnifications. The cell wall in a sample is weakened and is collapsing. Also, the growth of fungi can be clearly seen among the wooden structure. In the other two samples, the cellulosic walls are severely damaged and we see dissociation and rupture between the cellulosic layers.Conclusion:The results of this study showed that the wood used for historical lion heads is beech and mazo wood. Also, fungi such as Aspergillus terius, Alternaria, Aspergillus niger and Cladosporium were identified in the wood structure. In the following, the destruction of the cell wall and the decay of the wood structure were identified. Also, azure blue, syringe red, white flowers, as well as a mixture of carbon black and iron black colors have been used on historical wood as patterns and writings. This study can be very important for the proper preservation of historical wooden works of Gorgan region.
Wood Modification and Wood Preservation
Hamid reza Zarey; Reza Hajihassani; seyedeh masoomeh; Kamyar Salehi
Abstract
Background and Objectives: Wood has some limitations in properties and applications due to its natural nature, which need to be modified. Wood modification is usually done with different aims and methods. One of the wood modification methods is thermal treatments in order to improvement of dimensional ...
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Background and Objectives: Wood has some limitations in properties and applications due to its natural nature, which need to be modified. Wood modification is usually done with different aims and methods. One of the wood modification methods is thermal treatments in order to improvement of dimensional stability and biological resistance. But, it is surely affected on physical and mechanical properties of wood. Wood thermal modification in presence of oxygen causes the oxidation of its chemical structure which leads to decrement of physical and mechanical properties. Therefore, elimination of oxygen in thermal modification can reduce its destructive effects. In current study, the effect of thermo-oil process on the function of white rot fungus has been investigated. Moreover, the effect of this process on engineering properties of birch and pine wood species was evaluated.Methodology: In this study, two wood species of birch (Betula sp.) and pine (Pinus sp.) cut into the desired timbers. Heat treatment of the prepared timbers was carried out in a cylinder which equipped to the pressure and vacuum system. Also, industrial recycled oil was used for heat treatment of the timbers. The temperature and time treatment were considered 195 °C and 5 hours, respectively. At the end of the process, the used oil was drained into the oil storage tank and the timbers were removed from the cylinder after applying vacuum. In order to investigation of biological resistance as well as physical and mechanical properties (water absorption and swelling, density, mass loss, bending strength, compression strength parallel to the grain and impact strength) test specimens were prepared from the treated and control timbers based on the standard. The SPSS software was used for statistical analysis. The results were statistically analyzed based on a One-Way ANOVA method.Results: Results revealed that thermo-oil treatment can reduce the functionality of white rot fungus and also its efficiency on physical and mechanical properties of both wood species. Moreover, the results showed that this process improved the physical properties and reduced the mechanical properties, except compression strength parallel to the grain.Conclusion: Thermo-oil treatment at high temperature causes structural changes of wood and affects its physical and mechanical properties. Also, the structural changes caused by heat treatment can be an effective and inhibiting factor to functionality of white rot fungus on physical and mechanical properties of wood.
Wood Modification and Wood Preservation
َAmir Mohamad Nahofteh Estarabadi; Davood Rasouli; Taghi Tabarsa; Abolghasem Khazaeian
Abstract
Background and Objectives: Wood, as an organic material, is susceptible to deterioration by destructive factors such as fungi and insects. One approach to protect against these factors is the treatment of wood with preservatives. The use of waterborne preservatives is common due to the numerous advantages. ...
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Background and Objectives: Wood, as an organic material, is susceptible to deterioration by destructive factors such as fungi and insects. One approach to protect against these factors is the treatment of wood with preservatives. The use of waterborne preservatives is common due to the numerous advantages. However, when preservative-treated wood is exposed to outdoor environments, it becomes susceptible to weathering and leaching. The use of coatings can be an effective method in this regard. This research investigates the effectiveness of two transparent coatings, acrylic and alkyd, in enhancing the weathering resistance of wood specimens treated with waterborne preservatives. .Methodology: defect-free poplar wood specimens with dimensions of 12×10×2 cm3 (L, T, R) were prepared and then they were treated with preservatives ACC, CCB, and ACQ-C using the full-cell/pressure impregnation method. Subsequently, acrylic and alkyd transparent coatings were applied to the surface of the specimens. After applying the coatings, the specimens were exposed to natural weathering for one year.Results: The results indicated that the type of coating significantly influenced the color and adhesion resistance of specimens. Furthermore, the research findings demonstrated that all specimens experienced color changes and a decrease in coating adhesion resistance due to weathering. Among the coatings, the intensity of color changes and deterioration in specimens with acrylic coatings was higher compared to those with alkyd coatings. Conclusion: In general, it can be concluded that alkyd coatings exhibited better preservative performance against weathering for preservative-treated wood.Background and Objectives: Wood, as an organic material, is susceptible to deterioration by destructive factors such as fungi and insects. One approach to protect against these factors is the treatment of wood with preservatives. The use of waterborne preservatives is common due to the numerous advantages. However, when preservative-treated wood is exposed to outdoor environments, it becomes susceptible to weathering and leaching. The use of coatings can be an effective method in this regard. This research investigates the effectiveness of two transparent coatings, acrylic and alkyd, in enhancing the weathering resistance of wood specimens treated with waterborne preservatives. .Methodology: defect-free poplar wood specimens with dimensions of 12×10×2 cm3 (L, T, R) were prepared and then they were treated with preservatives ACC, CCB, and ACQ-C using the full-cell/pressure impregnation method. Subsequently, acrylic and alkyd transparent coatings were applied to the surface of the specimens. After applying the coatings, the specimens were exposed to natural weathering for one year. .Results: The results indicated that the type of coating significantly influenced the color and adhesion resistance of specimens. Furthermore, the research findings demonstrated that all specimens experienced color changes and a decrease in coating adhesion resistance due to weathering. Among the coatings, the intensity of color changes and deterioration in specimens with acrylic coatings was higher compared to those with alkyd coatings.Conclusion: In general, it can be concluded that alkyd coatings exhibited better preservative performance against weathering for preservative-treated wood. .Conclusion: In general, it can be concluded that alkyd coatings exhibited better preservative performance against weathering for preservative-treated wood. .
Wood Modification and Wood Preservation
Seyedeh Masoomeh Zamani; Reza Hajihassani; Kamyar Salehi
Abstract
AbstractThe purpose of this study was to evaluate effectiveness of brown rot fungus on ash (Fraxinus Sp.) and spruce (Picea Sp.) thermo-wood and also thermally modification on fungal functionality. In first step, prepared wood samples of both species were heat treated under 212 ºC for 3 hours. Afterwards, ...
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AbstractThe purpose of this study was to evaluate effectiveness of brown rot fungus on ash (Fraxinus Sp.) and spruce (Picea Sp.) thermo-wood and also thermally modification on fungal functionality. In first step, prepared wood samples of both species were heat treated under 212 ºC for 3 hours. Afterwards, heat-treated and untreated wood specimens were exposed to brown rot fungus for 16 weeks based on EN 313 and the functionality of fungal destructive agent and also its effect on physical and mechanical properties were finally analyzed. The obtained results showed that the brown rot fungus has been more efficiency on untreated specimens in compared with thermo-wood in both two wood species and caused more destruction and mass loss. Moreover, the results revealed that some physical and mechanical properties include density, compression parallel to grain and impact strength of exposed heated specimens to brown rot fungus were more than unexposed heated specimens to this fungus. Evaluation of laccase activity which produced by brown rot fungus showed more its effect on controls than heat treated specimens in both wood species. Based on the results, thermally modification can generally causes improvement of biological resistance, reduction of some physical and mechanical properties as well as more stability of applied properties of ash and Picea wood which exposed to the brown rot fungus.
Wood Modification and Wood Preservation
Atiye Sadat Mousavi-Sangdehi; Reza Oladi; Davood Efhamisisi; Maliheh Akhtari
Abstract
Biological protection is one of the rather new and environmentally friendly methods of wood protection, in which living microorganisms have replaced chemical substances. This research was carried out with the aim of investigating the biological protection of beech wood against the white rot fungus (Trametes ...
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Biological protection is one of the rather new and environmentally friendly methods of wood protection, in which living microorganisms have replaced chemical substances. This research was carried out with the aim of investigating the biological protection of beech wood against the white rot fungus (Trametes versicolor) using Trichoderma harzianum. For this purpose, the antagonistic ability of Trichoderma against wood rotting fungus was evaluated in dual culture medium as well as on wood. Trichoderma was incubated on wood samples in two time periods of four and eight weeks, and then samples were exposed to white rot for 16 weeks. The dual culture test proved the antagonism of Trichoderma against wood-destroying fungi, in a way that after 14 days, Trichoderma had not only prevented the spread of T. versicolor hyphae, but also overgrew on its mycelia. Cellulase enzyme assay showed that this isolate of Trichoderma had little ability to secrete this enzyme, and for that reason, sample weight loss due to fungal treatment was neglectable; a result that was also confirmed by infrared spectroscopy. The duration of wood incubation with Trichoderma was an important factor in the efficiency of treatment: increasing the time by one month significantly reduced weight loss of treated samples from 15% to below 1%, while the weight loss of the control samples was more than 30%. It can be concluded that the long-term treatment of beech wood with Trichoderma does not have a destructive effect on the wood and protects it against the white rot. Therefore, it is suggested to use this type of biological agent as a pretreatment of beech wood or to combine it with other preservative materials.
