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Amenability of radial permeability of Sitka spruce (Picea sitchensis (Bong.) Carr.) as affected by aspects of cell ends in uniseriate ray parenchyma tissue
2003 - IRG/WP 03-40252
The principal objective of this article was to recognise and understand the amenability of ray parenchyma cell ends (end platform) in uniseriate ray tissue to influence the radial permeability of Sitka spruce (Picea sitchensis (Bong.) Carr.) by examination of most (Queen Charlotte Islands in Rhondda, South Wales) and the least (South Oregon in Dalby, North-East England) seed origins that grown in Britain. These seed origins were selected because they showed extremes in radial permeability using a copper-chromium-arsenic wood preservative full cell treatment. Differences of radial permeability of this extreme seed origins were explained by a detailed examination of the structures of the uniseriate ray parenchyma cell ends by SEM and Image Analysis. The data of the microscopic observations was analysed and differences in cell composition and dimensions were observed. The results showed that the nature of the simple pits in ray parenchyma cell ends and the condition of the end platform were the most significant factors affecting radial permeability in Sitka spruce.
I Usta, M D C Hale

End grain sealants for wood preservation studies
1985 - IRG/WP 3341
The results of tests with possible end grain sealants for wood preservation studies are reported. The epoxy resins used gave satisfactory performance on wet or dry Sitka spruce and have been used with success for diffusion treatment studies.
R J Murphy, N A Summers

The influence of formulation on the behaviour of LOSP's during industrial impregnation of spruce
1986 - IRG/WP 3387
Evidence is presented that the comparative behaviour of two LOSP formulations during impregnation treatment of spruce cannot be predicted purely on the basis of their physical characteristics (viscosity, surface tension and contact angle) nor on the extent of their 'passive' penetration into pine sapwood.
L D A Saunders, D M Zuvencko

Butt-end incising to improve penetration and retention of creosote in Eucalyptus saligna power transmission poles in Kenya. Preliminary results
2002 - IRG/WP 02-40249
Incising as a possible technique to improve penetration and retention of creosote in the butt end of Eucalyptus saligna power transmission poles in Kenya was investigated. Debarked, butt-end samples from whole poles were seasoned (15% MC), incised using four patterns of incisions, sealed at the top or small diameter end, and pressure treated with a mixture of creosote-furnace oil (60/40 mix) at a commercial plant using a full cell process. They were then conditioned in the open for 3 months to allow evaporation, migration, and bleeding. The samples were subsequently leached in running tap water for 21 days, air-dried for 8 weeks under cover and retentions calculated on a weight-gain basis and compared. Discs were removed from the middle (450mm) of the samples, and radial penetration assessed visually and measured. Compared to un-incised samples, both penetration and retention were substantially improved in samples with closer incisions of 20 mm x 20 mm, by 58.6% or 89.8 mm and 87.0% or 146.4 Kg/m3 respectively. Wider incisions 0f 40 mm x 40 mm achieved lower improvements, 17.3% or 66.4 mm for penetration and 19.8% or 93.8 Kg/M3 for retention. The 4 incising patterns achieved consistently higher penetration and retention of creosote compared to un-incised control samples, which achieved lower average penetrations (56.6mm) and retentions (78.3Kg/M3). Butt-end, or incising the ground-contact sections of transmission poles may be a feasible technique for improving both penetration and retention in the more vulnerable portions of poles, and thus substantially increase service lives of eucalyptus poles in the country. Further investigations are necessary to establish patterns of incision and appropriate treatment schedules.
R Venkatasamy

A new model for wetting and drying of wood end-grain – with implications for durability and service-life
2011 - IRG/WP 11-20477
New experimental data for wetting and drying of wood end-grain, Sandberg (2009), imply that traditional models for moisture transport are not at all applicable. A new model is developed to consider the phenomenological behaviour of water transport in and out of end-grain, using the pore water pressure and sorption scanning properties. Modelling results are compared to experimental results and the consequences for durability are discussed.
L-O Nilsson, K Sandberg

Butt-end incising to improve penetration and retention of CCA in Eucalyptus saligna telegraph poles in Kenya: Preliminary results
2002 - IRG/WP 02-40243
Incising to improve penetration and retention of Copper Chrome Arsenate (CCA) in the butt end of Eucalyptus saligna telegraph poles was investigated. Debarked, seasoned (15% MC) butt-end samples from full size telegraph poles were incised using four patterns of incisions, sealed at the top or small diameter end, and pressure treated, together with un-incised samples, with CCA-C (3.0% oxide type) at a commercial pole treatment plant, using a full cell process. After conditioning under cover for 6 weeks to allow fixation and air-drying to 15% MC, samples were leached in running tap water for 12 days, re-dried to 15% MC, retentions calculated on a weight gain basis and compared. Discs were removed from the middle 50mm sections of samples, sprayed with Chrome-azurol S, and average radial penetration computed. In comparison to un-incised samples, both penetration and retention were substantially improved in samples with closer incisions of 20 mm x 20 mm, by 59.9 %, or 79.3 mm and 59.0%, or 28.3 Kg/m3 respectively. For the wider incisions of 40 mm x 40 mm, improvements were lower, 13.1%, or 56.1 mm for penetration and 19.7%, or 21.3 Kg/m3 for retention. Un-incised samples achieved consistently lower average penetrations of 49.6 mm and retentions of 17.8 Kg/M3. Butt-end incising maybe a feasible technique for improving the otherwise unacceptable short service lives of eucalyptus telegraph poles in the country. Intensity, depth, and method of incising, together with appropriate treatment schedules, need to be investigated further.
R Venkatasamy

Alternative timbers to Iroko (Milicia excelsa) for various end-uses: Ghana’s offer
2004 - IRG/WP 04-10518
There are hundreds of timber species indigenous to Ghana and several exotic species have been extensively planted. The timber industry in Ghana is very important to the country’s economy. Despite its small size relative to the world trade in timber products, it has the potential to be a driving force in the development of the Ghanaian economy. The industry is currently going through a period of change and restructuring which is largely brought about by the need to address the issues of a reducing resource and to use the available resource more efficiently and to greater economic benefit by promoting the lesser used species as alternatives to the over-exploited primary species and also by developing the tertiary processing sector. Iroko (Milicia excelsa) is one of the primary species currently facing extinction and Dahoma (Piptadanistrum africanus), Ekki (Lophira elata), Kusia (Nauclea diderrichii) and Papao (Afzelia bella) are lesser-used species being promoted as good alternatives to Iroko for various end uses. Properties (mechanical, biological) and volumes of these species are compared to those of Iroko.
S A Amartey, Zeen Huang, A Attah

Strategies for enhancing usage of treated wood in Indian context
2005 - IRG/WP 05-40305
India constitutes 2% of the world’s forest area but it has to support over 15% of the human and nearly 14% of the cattle population and therefore forests in India are under immense biotic pressure. The main concern today is the rate at which avoidable factors or man made threats accelerate the process of forest degradation and to evolve measures to check the same. Man made threats include exploitation and use of forests for commercial purposes in a non-scientific way. The need of the hour is to preserve our natural forests which can be done by utilization of man made forests scientifically. Wood continues to be an extensively used raw material for diverse, domestic, individual and structural applications such as housing, bullock carts, boats, toys, handicrafts, agricultural implements, furniture, fishing craft etc. Growing demands, diminishing supplies and the intensity of resource has led to acute shortage and phenomenal hikes in prices of conventionally preferred species and therefore, attention is now diverted towards fast growing plantation species to augment wood supply. However, most of these timber species are naturally non-durable or moderately durable and need protection from biological aspects like fungi, bacteria, termites, borers etc. Technologies such as preservative treatments can enhance the service life of timber several times and can save millions of well grown trees. However, the quantity of timber being treated in India is negligible as a favorable operation regime for scientific processing especially wood treatment does not exist. Compounding the problem is extremely weak, user group-researcher linkages, low level of technology development, technology absorption, extension efforts and non existence of R & D industry-researcher- end user association. These issues are discussed in detail in this paper.
P K Aggarwal, S C Gairola

Preservative treatment specifications in Fiji
1982 - IRG/WP 3190
The preservative treatment specification used in Fiji is outlined. Reference is made to a basic end use classification and to locally approved treatment processes, preservatives and retention levels. Amenability ratings are defined and penetration requirements for broad commodities indicated. Currently commercial operations rely entirely on pressure treatment with copper-chrome-arsenic multisalts and sodium arsenite - sodium pentachlorophenate formulations. The specification ie not at present mandatory, but legislation governing all aspects of commercial preservative treatment is currently being considered.
A S Alston

End grain sealing by polymer impregnation
1992 - IRG/WP 92-3708
The solution and dispersion characteristics of several hydrophobic derivatives of cellulose have been studied and the abilities of these polymers to afford effective end grain sealing of Corsican pine have been examined. Both solution and dispersion treatments with ethyl cellulose imparted good water repellency and end grain sealing to wood samples, however, the disperse systems possessed lower viscosities. Scanning Electron Microscopy (SEM) of treated samples and polymer radiolabelling/autoradiography studies indicated pit-membrane pore filtration of polymer particles close to the end grain. A range of esters (C2-C18 side chains) of Hydroxypropyl Cellulose have been prepared and characterised (FTIR, NMR). The acetyl, propyl and butyl esters formed coherent, flexible films. The C6, C9, C10 and C11 esters were essentially gums. However, the C18 (stearoyl) ester was found to form strong, wax like films, due to pronounced ester side-chain interactions. A number of the polymers were applied to Corsican pine test samples. Water repellent ability was found to strongly parallel the ability of the derivatives to form coherent polymer films. The C18 (stearoyl) ester exhibited impressive end grain sealing; outperforming all other systems tested at equivalent application levels. This work indicates that hydrophobic polymers that readily form strong films from solution or dispersion afford enhanced end grain sealing as compared to materials that simply produce a hydrophobic effect.
J M Lawther, W B Banks, D G Anderson, J A Cornfield

End Coating Masson Pine Grown in South China to Prevent the Development of Blue Stain
2007 - IRG/WP 07-30428
One end (randomly selected) of logs of mason pine (Pinus massoniana) were coated with a wax-type end coating called ANCHORSEAL® immediately after tree cutting. The logs were then stored in summer weather in Guangxi, China. During the storage, at week 1, 2, 3, 4, 6, 8 and 12, five logs of mason pine were sawn into lumber or veneer for the visual observation and measurement of blue stain at the coated and uncoated ends; The results showed that the average length of blue stain in mason pine logs was 226 mm for uncoated ends and 119 mm for coated end after 12 weeks of storage. The safe storage time for mason pine logs is up to one week without blue stain development. For uncoated logs, the safe storage period is less than 6 weeks if the losses caused by blue stain are to be kept at less than 17% for 2-meter long logs. For the coated logs, the safe storage period is under 6 weeks if the losses are to be kept at less than 8.5% for 2-meter long logs. ANOVA analysis showed that there existed significant differences in blue stain for mason pine. That means the effects of end coating are significant for preventing the development of blue stain. The volume losses caused by blue stain are nearly 11% for 2-meter long logs after 12 weeks storage. The sawmill can save 7.7% of the value of the mason pine. As the cost of coating is much less than the value of benefits, end coating of logs during storage is recommended.
Zhao Youke, Qin Li, Huang Rongfeng, Lu Jianxiong

Radial flow of Bornmullerian fir (Abies bornmulleriana Mattf.) as affected by wood tapering and the condition of end wall structure of uniseriate ray parenchyma cells
2008 - IRG/WP 08-40441
Amenability to radial permeability of Bornmullerian fir (Abies bornmulleriana Mattf.) was studied on the base of the effects of wood tapering and the structure of end walls of uniseriate ray parenchyma cells. The results showed that the most remarkable culprits of the greatest fluid uptake (as the percentage of void volume filled by the fluid in the radial flow direction, RVVF%) are the lesser wood tapering and a slight inclination of the end walls. It was also noticed that the thinner end walls having the larger apertures of the simple pits influence to RVVF%. It could be therefore stated that both wood tapering and the situation of the end walls of uniseriate ray parenchyma cells were the most important factors for regulating radial flow for Bornmullerian fir.
I Usta, S Aslan

Performance of dip and pressure treated wood in termite ground proximity exposures in Hilo, HI, and Colombia
2008 - IRG/WP 08-30491
A number of preservative systems were evaluated for their ability to control termite attack when applied as both dip and pressure treatments. With dip treatments, better performance was observed with southern pine than spruce-pine-fir using the same solution strength treatment, probably as a result of the about 50% greater uptake with southern pine and associated deeper preservative penetration. Boards that were cross-cut after treatment suffered much great attack, suggesting that the shell treatment does not provide any protection to post treatment cut ends. There were also indications that the type of cover used in the termite ground proximity test may greatly influence the activity of the termites in the arrays.
P Walcheski, A Zahora

Durability of reaction to fire performance of FRT wood products in different end use applications – Methods and results
2015 - IRG/WP 15-40705
Fire retardant treatments (FRT) may considerably improve the reaction to fire properties of wood-based products and the highest fire classifications for combustible products can be reached, but the maintained reaction to fire performance e. g. in exterior applications needs to be addressed in order to form a basis for new and reliable wood products with improved fire performance. A European Technical Specification with Durability of Reaction to Fire performance (DRF) classes has been developed in order to assist product development and to guide potential users to find suitable FRT wood products. It is based on ASTM standards and has been further developed upon Nordic initiatives from industry and research as Nordtest methods. It consists of a classification system for the fire properties over time of FRT wood and test procedures for hygroscopicity and accelerated weathering covering both interior and exterior applications. The European system has been applied to a range of commercial FRT wood products and products under development and a long term experimental study on the maintained reaction to fire performance of FRT wood products over time has been performed. It includes accelerated ageing according to different procedures and natural weathering up to ten years. Main conclusions are: - The hygroscopic properties are unchanged compared to untreated wood for most commercial FRT wood products - The reaction to fire properties of FRT wood may be maintained after accelerated and natural ageing if the retention levels are high enough - Several FRT wood products loose most of the improved reaction to fire properties during weathering - Paint systems contribute considerably to maintain of the fire performance at exterior application The results of the long term study show that requirements for interior applications of FRT wood products often are fulfilled, while products for exterior applications with maintained fire performance over time are rare. There is thus a strong need for product development for exterior applications. In the meantime, requirements on the long term durability of the fire performance of FRT wood products should be included in the national building regulations. There is also a need to determine the relationship between accelerated and natural weathering in different climates in order to further develop the conditions for accelerated weathering.
B Östman, L Tsantaridis

Life cycle assessment of creosote treated wood and tall oil treated wood with focus on end-of-life
2016 - IRG/WP 16-50320
The use of creosote for protecting wood products in heavy-duty application outdoors has been common for many years, but stricter regulations have limited creosote’s use. Life cycle assessments (LCA) have shown that in some applications alternatives to creosote treated products do not have less environmental impacts. Searching for alternatives to creosote, tall-oil-based preservatives have been of interest; in this regard, a LCA study has therefore been performed to compare the creosote and tall oil treated products according to their impacts on global warming potential (GWP). There are several approaches to include the removal and release of biogenic carbon in LCA. Under current end-of-life scenarios for treated wood, the different approaches give the same total impact on GWP when the whole life cycle is included. However, if carbon capture and storage is implemented at end-of-life of treated wood, the different approaches have large differences in the results. Tall oil treated wood has been shown in this study to have a relatively large contribution to GWP compared to creosote treated wood from a cradle-to-gate perspective. When the whole life cycle is included, the tall oil has a relatively lower contribution to GWP. This is because tall oil is from a renewable resource and that the combustion at end-of-life thus has a significantly lower impact than fossil-based creosote.
L G F Tellnes, U Hundhausen

Durability of energy efficient wooden buildings: a building physical point of view
2017 - IRG/WP 17-40812
The drive for more energy efficient and sustainable buildings resulted in an increased popularity of wooden buildings, even in countries with a masonry tradition. Often guidelines and prescriptions then are copied from other countries. Different climatic boundary conditions and tradition of finishing, though, do require different moisture tolerance criteria. This is clearly the case for water vapour related damage. The current paper evaluates the durability of wood constructions from a building physical point of view. Focus is on moisture risks due to the combined heat, air and moisture transport trough wooden building components. Starting from the steady state analysis of pure vapour diffusion across a building component, the complex problem is stepwise analysed. The effect of hygric buffering in the wooden elements, different moisture sources and the impact of air transfer on the moisture tolerance are studied. Applications are shown for two types of components: the traditional lightweight walls as applied in platform framing and the more recent Cross Laminated Timber, which becomes increasingly popular as alternative for traditional framing.
S Roels, J Langmans

Long service life or cascading? The environmental impact of maintenance of wood-based materials for building envelope and their recycling options
2018 - IRG/WP 18-50336
A major restraint in choosing bio-based materials (i.e. wood-based) for external use, is the lack of confidence that architects, designers and customers have toward these materials. In particular, the limit state of bio-based materials, which defines the frequency of maintenance operations, might be reached earlier for wood than for other materials (i.e. concrete). On the other hand, resource and energy scarcity together with increasing concern for climate change consequences are raising the demand for competitive bio-based materials in the built environment as substitutes for other energy-intensive materials. Therefore, novel and traditional protective treatments are used to improve the performance of woody materials for outdoor use. Nonetheless, the environmental and economic burden of such treatments is often unknown. The number of LCA (life cycle assessment) studies on the topic is low, with geographically sparse data and non-uniform assessment protocols. This study provides a novel approach to assess the in-service performance, maintenance requirements and end-of-service-life options for over one hundred bio-based materials for façades. The protection techniques of the materials under examination include: chemical modification, thermal treatment, impregnation, hybrid treatments, and surface treatments (bio-film, coating and nanocoating). Natural, untreated wood and composite materials such as wood-plastic composites are included as well. The in-service environmental performance is analysed by considering the amount of material, energy, water and waste that are used and/or produced to maintain one square meter of façade. The options for end-of-service-life include: panel manufacturing, pelletizing, animal bedding, liquefaction, insect conversion, fungal conversion, combustion, incineration, gasification and pyrolysis, anaerobic digestion, fermentation, composting and landfilling. For each material group, the possibility for cascading use is assessed. The overall goal is to increase the confidence in bio-based building materials by tackling environmental issues related to wood modification processes.
M Petrillo, J Sandak, P Grossi, A Kutnar, A

Conversion by insects – alternative method for wood waste up-cycling
2018 - IRG/WP 18-50337
Building industry is a major consumer of materials and waste generator in Europe. The bio-based building materials are considered as interesting alternative in modern building sector due to their low environmental impact. However, in order to increase confidence for bio-based materials application, they should present satisfying performance during service life allowing at the same time their cascade use, material and/or energy recovery and recycling. New development in the wood modification offer well-performing solutions even in severe environments. However, the advantage of the high resistance against biological degradation can become a restraining factor at the end of their service life. Presented research is a part of the BIO4ever project, where beside of modelling of service life performance, alternative end-of-life solutions for novel facades biomaterials are investigated. The efficiency and ability of insects to convert different categories of materials was investigated during 24 weeks of laboratory tests with selected termite species. Considering discriminatory choice of termites, it can be stated that at least some of the materials category might be converted into valuable protein source at their end-of-life. The investigated termite species Reticulitermes flavipes was recently classified among edible insects. Proposed solution might therefore contribute to the global problem of nutrient deficiency by providing recommendation of the use of building biomaterial wastes as an alternative feedstock for further transformation into proteins.
A Sandak, J Sandak, M Kutnik, I Paulmier, C Brunet, M Petrillo, P Grossi

Performance of field cut preservatives above-ground and in ground contact exposures
2019 - IRG/WP 19-30742
Field cut preservatives are needed to protect cut ends and drill holes that expose the untreated interior of preserved wood. A series of field cut preservatives were assessed in ground contact and above-ground exposures. After 10 years in ground contact exposure, all of the untreated controls had failed or exhibited very advanced decay. In contrast, the copper naphthenate (2% Cu in mineral spirits) reference showed only low levels of decay in a few specimens. No decay was detected on specimens treated with copper azole. ACQ-D had similar levels of decay as the reference. After 10 years in an above-ground exposure, advanced decay was present on several of the untreated controls. In contrast, the copper naphthenate (2% Cu in mineral spirits) reference remained sound. Specimens treated with copper naphthenate (1% in water) and copper azole were also largely sound, with a few specimens showing early stage decay.
R Stirling, D Wong

The InnovaWood Module Bank: Building an international e-learning platform for shared MSc courses in wood science and technology
2019 - IRG/WP 19-50355
The InnovaWood Module Bank is a shared e-Learning platform for standalone science, technology and education modules in wood science. A group of members of InnovaWood have committed to jointly develop this platform. The institutes benefit in that they can widen the range of courses they offer and use their teaching capacities more efficiently. Students obtain the possibility to take online courses at another university without the need of costly exchange programmes. New e-Learning tools and teaching methods give them more choice and more flexibility to pursue their own individual preferences during their studies. To participate in the Module Bank, organisations must commit to providing at least one module of 3 ECTS at the MSc level. In return they obtain access to the whole series of modules that are offered collectively. The main benefits are that an institution obtains access to high quality lectures of experienced teachers in specific thematic fields and the opportunity to complement their core study programmes with additional online modules. Among others, these contain a module on ‘Wood degradation and wood protection’ by the University of Göttingen, which is relevant for IRG. The Module Bank contributes to new internationalisation experiences and a diversification of teaching contents and formats.
M Irle, U Kies, H Militz, P Sauerbier, M Vieux, A Prosic, B Wolfsberger, F Pichelin, I Mayer

Is cascading of harvested wood products really an environmentally beneficial strategy in Finland and Norway?
2020 - IRG/WP 20-50364
The role of cascading wood waste in the bioeconomy is highlighted in the several strategic documents. The European Waste Framework Directive describes a waste hierarchy where re-use and recovery are considered more favourable options compared with energy recovery, and applies strict re-use and recycling targets to household waste and non-hazardous construction and demolition waste. It is not fully clear if setting such targets will result in a positive environmental benefit. The assumption is generally made that cascading of bio-materials is good and incineration is bad. But how true is this assumption and is it universally applicable? This paper discusses the methodology to be used in order to determine the best strategy for the use of end of life wood waste in Norway and Finland. The scenario considered is that of the cascading of wood at the end of life into different product categories as counterfactuals compared to the incineration of wood with energy recovery. The paper considers both the LCA aspects by comparison of the global warming potential of different scenarios, as well as the storage of atmospheric carbon in the materials. Knowledge gaps that need to be covered in order to determine the best approach to utilising wood waste from an environmental perspective have been identified.
C A S Hill, G Alfredsen, M Hughes, L R Gobakken