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Quantification of four dark colored mould fungi by real time PCR
2011 - IRG/WP 11-10754
Coated wooden claddings in building facades are widely used in the Scandinavian countries, and are often preferred to other materials. Wood is facing increasing competition from other materials that are less labor intensive at the construction site and materials with less demand for maintenance thru service life, and makes further development of wooden claddings essential. Growth of discoloring moulds on exposed coated wooden claddings is mainly of aesthetic concern, and is especially disfiguring for light-colored surfaces. Growth of surface fungi often initiates repeated cleaning and shorter maintenance intervals, which in turn increase the total cost of ownership for wooden claddings. Cost and effort of ownership are often important factors considered when choosing a product, and the traditionally good market situation for wooden claddings is therefore threatened. The development of real-time PCR (polymerase chain reaction) and taxon-specific primers has provided new possibilities for specific detection and quantification of fungi in their natural substrates. In qPCR (quantitative real-time PCR), the accumulation of the PCR product is detected for each amplification cycle. An efficient and reproducible sampling and extraction of DNA is required for a high-throughput qPCR based quantification of discoloring fungi. The authors have now adjusted DNA isolation protocols and optimized real-time PCR assays for species specific detection of fungi frequently found on painted surfaces (Aureobasidium pullulans, Alternaria alternata, Cladosporium cladosporides, Ulocladium atrum).
E Larnøy, L Ross Gobakken, A M Hietala

Screening potential preservatives against stain and mould fungi on pine timber in Zimbabwe
1995 - IRG/WP 95-30063
The search for environmentally and toxicologically safer chemicals for use in the timber preservative industry against stain and mould fungi has been intensified during the past few years. Results of field tests with two chemicals previously evaluated in the laboratory are presented. The conventional sodium pentachlorophenate was the more efficacious chemical against stain and mould fungi, providing up 90% control at a concentration of 2.5%. A potential alternative, Stopstain a borate-based chemical, gave results only slightly better than the untreated control timber, at a concentration of 5%. Unless the environmental cost and toxicological hazards of traditional chemicals are highlighted the newer and safer chemicals will be reluctantly accepted by industry as they are regarded as being prohibitively expensive.
A J Masuka

Mould resistance of lignocellulosic material treated with some protective chemicals
1984 - IRG/WP 3294
Effectiveness of preserving lignocellulosic material against moulding by treatement with water solutions of commercial wood preservatives and mixtures of various inorganic salts was investigated and compared with the effectivenes of sodium pentachlorophenoxide and boric acid.
K Lutomski

Observations on the colonization of freshly-felled timber treated with prophylactic chemicals by mould and sapstain fungi
1989 - IRG/WP 1394
Field tests using freshly felled pine sapwood were set up to determine the effectiveness of a range of antisapstain compounds and to study the problems of colonization by mould and sapstain fungi. Differences were recorded both in the overall performance of the compounds and also their selectivity in controlling specific fungal types. These results were found to be useful in gaining a better understanding of biocide - fungal interactions.
G R Williams, D A Lewis

Proposed degradation pathway for quaternary ammonium compounds by mould fungi
1996 - IRG/WP 96-10166
One group of chemicals that has attracted considerable attention as potential wood preservatives are the quaternary ammonium compounds (QACs). Based upon results of previous research this study confirmed the degradation pathway employed in QAC-tolerant fungi. For this experiment the two dialkylammonium compounds didecyldimethylammonnium chloride and dioctyldimethylammonium chloride were used. QAC-treated wood blocks were inoculated with the tolerant fungi Gliocladium roseum and Verticillium bulbillosum. After incubation the remaining QACs were extracted with acidified acetonitrilic and HPLC was used to quantify and detect the degradation products.
J L Bürgel, J Dubois, J N R Ruddick

Growth of two selected sapstain fungi and one mould on chitosan amended nutrient medium
2003 - IRG/WP 03-10466
In vitro studies were undertaken to investigate the effect of chitosan on growth of Leptographium procerum, Sphaeropsis sapinea and Trichoderma harzianum. Chitosan was tested at three molecular weight (MW) ranges and different concentrations formulated as either a powdered suspension or as a solution. The results generally showed that low MW chitosan produced a greater inhibitory effect on growth of test fungi than medium and high MW, irrespective of the chitosan formulation used. However, chitosan was more effective when applied in solution with much lower concentrations exerting inhibition of test fungi than chitosan suspensions. Furthermore, susceptibility of test fungi to chitosan differed, with T. harzianum being the most tolerant and S. sapinea the most sensitive species irrespective of chitosan formulation used.
C Chittenden, R N Wakeling, B Kreber

In vitro studies on the effect of chitosan on mycelial growth and spore germination of decay fungi, moulds and staining fungi
2004 - IRG/WP 04-10507
The effect of solubilised, low molecular weight chitosan on established mycelial growth of a range of decay fungi, moulds and staining fungi was investigated using nutrient medium amended with different concentrations of chitosan that ranged from 0.1 to 0.4% weight per volume (%w/v). Also, spore germination of Trichoderma harzianum and Leptographium procerum was examined on chitosan amended nutrient medium using visual and microscopic assessment. The results showed that chitosan affected mycelial growth of a wide range of test fungi which generally showed lower growth rates as the chitosan concentration increased. However, the degree of inhibition exhibited by chitosan varied with fungal species. Under the present test conditions, chitosan was fungistatic, but not fungitoxic, against established mycelium of the staining fungi tested and also two moulds, Botrytis cinera and Cladosporium herbarum, but not against any of the decay fungi tested. Spores of T. harzianum germinated on chitosan amended nutrient medium at all chitosan concentrations tested, except for the highest level (0.2%w/v) used, while L. procerum failed to germinate on 0.15 and 0.2%. Also, T. harzianum and L. procerum spores incubated on 0.15% and 0.2% chitosan failed to germinate when placed onto fresh malt extract agar suggesting fungitoxic activity of chitosan at these higher concentration levels.
C Chittenden, B Kreber, N McDowell, T Singh

Resistance of painted pine sapwood to mould fungi. Part 1. The effect of waterborne paints and fungicides on mould growth
1997 - IRG/WP 97-10233
The efficacy of different fungicides in acrylate and alkyd paints to protect pine sapwood against mould fungi was studied. The acrylate and alkyd paint systems with and without a preservative dipping treatment prior to painting were also used. Differences in the efficacy of the fungicides to protect the paint film were found. The paint films with isothiazolon and IBPC were resistant against mould fungi but the paint films with propiconazole were susceptible to mould. The mixture of propiconazole and IPBC or propiconazole and isothiazolon performed well even at a low concentration. The dipping treatment alone and some fungicides in the paint films supported even higher mould growth than was observed on untreated wood. The most effective combinations were free from mould growth after 26 weeks at RH 100%. In future, the effect of 26 weeks' natural weathering on mould growth will be assessed and the results of the mould test and natural weathering will be compared. The study is a part of a project CT94-2463 in the AIR programme of DG XII.
H Viitanen, P Ahola

Antifungal properties of new quaternary ammonium and imidazolium salts against wood decay, staining and mould fungi
2004 - IRG/WP 04-30347
The biological activity of twenty-four potential wood preservatives – imidazolium and quaternary ammonium salts with a modified anion structure was determined employing screening agar-plate and agar-block methods. Experiments were carried out on Scots pine (Pinus sylvestris L.) wood. The aim of the performed studies was to investigate the effect of structure modification of IC and QAC with organic anions or copper (ll) and zinc complexes on their biological activity against wood decay, staining and mould fungi. The fungicidal value of new compounds for Coniophora puteana ranged from 0.64 kg/m3 to 2.2 kg/m3. Aspergillus niger turned out to be the most resistant fungus to the action of modified IC and QACs, whereas Sclerophoma pityophila was effectively inhibited by the examined salts. The performed soil-block tests showed that the IC and QAC were leached from the experimental wood in conditions of contact with moist soil and revealed their fungal detoxification by mould fungi, especially by Gliocladium roseum. Observations made using the scanning electron microscope of the colonization and decay of treated wood by mould fungi confirmed tolerance of mould fungi to QACs.
J Zabielska-Matejuk, W Wieczorek

The yeast Pichia sp. As a short-term biological control agent to fungal spoilage of sawn softwood timber
2000 - IRG/WP 00-10362
Previous work has found isolates of the yeast Pichia to be a successful biological control agent toward moulding of fruits. An isolate was tested for the ability to protect sapwood of Pinus sylvestris timber against visual degrade by surface growth of moulds and staining fungi. Successful protection of autoclaved wood sprayed with a mixture of common wood moulding fungi was achieved when the yeast was applied at a rate of 6 x 10 8 cells/cm2. Yeast cells were sprayed onto the wood blocks at the same time as the fungi and blocks were incubated under conditions favourable to fungal development for 15 and 25 days before assessment using a visual scale. Limitation of the disfigurement of green wood required a similar cell application rate. Protection of blocks sprayed with Ophiostomatoid staining fungi following sterilisation required a lower concentration of yeast cells (2 x 10 6 cells/cm2). Survival and reproduction of Pichia cells on sterilised wood blocks was also determined across a range of relative humidity and temperature conditions previously found to support development of wood moulding and staining fungi. Following 16 weeks incubation at temperatures of 8-25°C at relative humidity 93-100%, between 46 and 473% of the number of colony forming units applied to the wood were recovered. Maximum increase in viable yeast cell count on wood blocks occurred at 100% relative humidity and 15°C.
C Payne, H J Staines, A Bruce

Resistance of painted wood to mould fungi. Part 2. The effect of wood substrate and acrylate paint systems on mould growth
1997 - IRG/WP 97-10234
Resistance of acrylate paint systems on different types of pine and spruce sapwood to mould fungi was studied. Dipping into the preservative prior to painting, a primer with and without a fungicide (propiconazole + IPBC 0.50 + 0.2%) and a topcoat with and without a fungicide (propiconazole + IPBC 0.25 + 0.12%) were combinations of the treatments studied. The efficacy of the treatment systems varied, but the wood material also affected the ability of the paint systems to resist mould growth on the paint surface. The kiln-dried yellow surfaces of the pine and spruce sapwood were more susceptible to mould growth than the spruce surface sawn 10 mm below the original kiln-dried surface. On the resawn spruce material, the most effective treatments were free from mould growth after 26 weeks at RH 100%. However, the effect was markedly lower on the kiln-dried surfaces of pine and spruce sapwood. The influence of natural weathering on the mould growth will be a next stage of the study. The study is a part of a project CT94-2463 in the AIR programme of DG XII.
H Viitanen, P Ahola

SEM investigation of the production of extracellular mucilaginous material (ECM) by some wood inhabiting and wood decay fungi when grown in wood
1997 - IRG/WP 97-10193
Previous reports have illustrated the involvement of extracellular mucilage (ECM) in wood decay by Basidiomycetes. Its production is investigated in a range of stain, mould and soft rot fungi in Corsican pine, Scots pine and European beech. Fungi examined were: Chaetomium globosum, Ceratocystis coerulescens, Trichoderma harzianum, Ophiostoma piceae, Mucor sp. and Penicillium. sp. The samples were examined in the frozen hydrated (FH) and freeze dried (FD) conditions using SEM. Most of the fungi tested produced ECM with the amounts produced varying from one fungus to the other. Different morphological forms of the mucilage were observed. ECM produced by C. coerulescens was mostly fibrillar, and interesting morphological forms of the ECM were associated with hyphae of T. harzianum. Small amounts of mucilage were produced by O. piceae and Penicillium sp. Further investigation is necessary on the ECM production in Mucor sp.
A R Abu, D J Dickinson, R J Murphy

Standardisation of sapstain tests - A challenge
1992 - IRG/WP 92-2403
In the last decade many new anti-sapstain products have been tested world-wide under laboratory and field conditions. Several extensive test programmes have been executed with different non-standardized test methods and procedures, with the result that the biological findings cannot be compared with each other. In this paper, gathered recommendations will be given in order to standardize test methods. These recommendations are based on questionnaires which have been sent to institutes throughout the world. For the realization of such a (standarized) test methodology, co-operation between test institutes, industry and working groups is necessary. This co-operation might also be useful for improving the treatment and application methods in the field. Standardization of sapstain methods is a challenge for Working Group II.
G Rustenburg, C J Klaver

Variation in infection rates of blue-stain, mould and white rot tropical fungi on mixed light Malaysian woods
2000 - IRG/WP 00-10334
The modified 3-week FRIM laboratory method for screening of anti-sapstain formulations against three representative tropical fungi causing blue-stain (Botryodiplodia theobromae), mould (Paecilomyces variotii) and white rot (Schizophyllum commune) infection of sapwood species was used to examine the relative resistance of the sapwood of eight mixed light Malaysian woods, Scots pine (Pinus sylvestris), medium density fibreboard produced from Rubberwood (Hevea brasiliensis) and the heartwood of Sentang (Azadirachta excelsa), to infection by these organisms. After 21 days it was found that Ramin (Gonystylus spp.), Rubberwood, Mersawa (Anisoptera sp.), Ludai (Sapium spp.), Yellow meranti (Shorea spp.), Scots pine and Jelutong (Dyera costulata) were highly susceptible to the pooled combinations of blue-stain, mould or white rot infection often sustaining >50% overall mean fungal coverage or when at least one of the infection types has reached maximum mean coverage (75.5%) of the wood samples. However, the Rubberwood-based fibreboard, and particularly Sentang, and the softwood Agathis spp. from Kelantan (trade name: Damar minyak) and Sarawak (trade name: Bindang), were relatively moderately susceptible to infection, sustaining between 9 and 47% overall mean fungal coverage after 21 days, or even considerably less susceptible (5 - 20% overall coverage) after 14 days. There was absence of both blue-stain and white rot fungal growth on all samples dipped in a low (0.03%/0.03%) fungicide concentration of a MBT/TCMTB anti-sapstain formulation. Such laboratory test results could have significant implications to field or industrial sapstain control of sapwood timbers concerning the lag time between tree felling and anti-sapstain treatment and seasoning.
A H H Wong, S Ahmad

The fungal degradation of quaternary ammonium compounds in wood
1998 - IRG/WP 98-10263
This work focuses on the biodegradation of didecyldimethylammonium chloride (DDAC) by the mould fungus Gliocladium roseum within a woody matrix. Three sawdust types, distinguished by their treatment and amount of DDAC retained, were inoculated with the fungus and their DDAC loss was measured over 11 weeks. The rates of degradation varied depending on the sawdust; however, a significant loss of DDAC was observed for all three. A metabolic by-product coincided with the fungal degradation of DDAC. The metabolite was separated using preparative HPLC and identified by proton-NMR and infrared spectroscopy to be a hydroxylated QAC.
J W Dubois, J N R Ruddick

The critical moisture and temperature conditions for the growth of some mould fungi and the brown rot fungus Coniophora puteana on wood
1988 - IRG/WP 1369
The growth of some mould fungi on pine and spruce sapwood was studied in 40 different constant moisture and temperature conditions. The temperature range was between +10 and +40°C and the relative humidities varied from 76 to 100% relative humidity (RH). The incubation time was 12 weeks. The mixed mould inoculation used included typical fungi growing on wood: Aspergillus versicolor, Cladosporium sphaerospermum, Penicillium sp., Aureobasidium pullullans and other fungi, which were collected from the air in the Forest Products Laboratory. The growth of Coniophora puteana was studied at +20°C and the relative humidity range was between 76 and 100% and the incubation time 60 weeks. The studied moulds grew rapidly in higher humidities (RH > 96%). The lowest humidity for growth was 80%, where the growth was very slow and it could be detected only by microscopy. At higher temperatures the growth was faster and the needed relative humidity was lower than it was in lower temperatures. The brown rot fungus Coniophora puteana grew only at 96-100% RH conditions, where the moisture content of wood was over 25 weight%. The growth was very slow at 96% RH, and after one year incubation the weight losses were quite low. The mycelium strands could mainly be clearly detected, but in some cases no mycelium could be detected on the surface of wood, even if weight losses were measured.
H Viitanen, L Paajanen

Resistance of painted wood to mould fungi. Part 3. The effect of weathering, wood substrate and fungicides on mould growth
1998 - IRG/WP 98-10284
The effect of 6 month outdoor weathering on the resistance of acrylate paint systems on different types of pine and spruce sapwood to mould fungi was studied. Dipping into the preservative prior to painting, a primer with and without a fungicide (propiconazole + IPBC 0.50 + 0.2%) and a topcoat with and without a fungicide (propiconazole + IPBC 0.25 + 0.12%) were combinations of the treatments studied. Weathering decreased ability of the fungicides to protect the paint films. The kiln-dried yellow nutrient rich surfaces of the pine and spruce sapwood were more susceptible to growth of bluestain and mould fungi than the spruce surface sawn 10 mm below the original kiln-dried surface. The most effective treatment combinations on the resawn spruce material were able to give a sufficient protection against bluestain and mould after outdoor weathering and subsequent 23 weeks incubation at RH 100%. However, the effect was markedly lower on the kiln-dried surfaces of pine and spruce sapwood. On the samples without the fungicide, decay was also found. The study is a part of a project CT94-2463 in the AIR programme of DG XII.
H Viitanen, P Ahola

Preservative effect of cellulose insulation material against some mould fungi and brown rot fungus Coniophora puteana in pine sapwood
1991 - IRG/WP 1484
The influence of mineral wool and loose-fill cellulose wool on biodeterioration of pine sapwood was studied. The test fungi were mould fungi Aspergillus versicolor, Cladosporium sphaerospermum, Penicillium sp. and Aureobasidium pullullans and brown rot fungus Coniophora puteana. Cellulose wool inhibited the growth of mould fungi on the face of wood contacted with insulation material at RH of 97 and 100%. During 6 months' incubation boron compounds added in cellulose wool diffused into the wood. No growth of brown rot fungus was detected in "treated wood". Mineral wool had no preventive effect on the growth of mould fungi and brown rot fungus Coniophora puteana.
H Viitanen

Aspects of the fungal degradation of quaternary ammonium compounds in liquid culture
1997 - IRG/WP 97-30160
Didecyldimethylammonium chloride (DDAC) is a quaternary ammonium compound (QAC) that has found use as an anti-sapstain preservative for the transportation of softwood lumber from Canada to overseas markets. However, its use is limited by the knowledge that certain mould fungi seem capable of degrading it. The aim of this research was to gain knowledge about the fungal degradation of DDAC. The effects of Verticillium bulbillosum - a demonstrated QAC-degrading mould - on DDAC within a defined liquid culture were studied. Interactions between the liquid medium and DDAC; the degree of fungal tolerance under varying conditions; and rate of degradation paralleled with fungal growth were examined.
J W Dubois, J N R Ruddick

Differential susceptibility of living and dead timber to colonisation by sapstain and mould fungi
1998 - IRG/WP 98-10288
Field studies have revealed that when timber is irradiated (i.e. killed) it is more susceptible to colonisation by mould fungi than sapstain fungi. By comparison, freshly sawn timber shows very little mould colonisation, tending to be colonised by sapstain fungi. It appears, therefore that the physiological state of the wood may influence the pattern of colonisation. A laboratory trial was undertaken to investigate in more detail the observations recorded in the field studies. A spore suspension of the mould Trichoderma was used to inoculate one set of living and one set of gamma irradiated (dead) wood blocks; similar sets of blocks were inoculated with a spore suspension of the sapstain fungus Ophiostoma piceae and a final treatment consisted of inoculating further sets of blocks with a mixed spore suspension of both fungi. Results clearly indicated that Trichoderma rapidly colonised and discoloured the irradiated blocks whereas there was very little defacement on the living blocks. The dead wood blocks inoculated with the mixed spore suspension were also rapidly colonised by the mould Trichoderma and 0. piceae was clearly out competed. However the living wood blocks were predominantly colonised by 0. piceae when they were inoculated either alone or in combination with Trichoderma. The factors controlling these patterns of colonisation are being investigated.
J R Williams, D J Dickinson, J F Webber

Models of the critical time of humidity and temperature conditions for the development of mould fungi in pine and spruce sapwood
1995 - IRG/WP 95-20066
Regression models of the time factor for the growth of mould fungi in pine and spruce sapwood are studied. The first group of models are based on the results of exposures of mould fungi in static humidity and temperature conditions indicating the time for the start of mould growth in wood. The second group of models are based on the exposures of mould fungi in fluctuating or alternating humidity and temperature conditions when limited models are presented. An aspect of surface quality (nutrient rich, nutrient poor) and wood species (pine, spruce) are included in the models. The growth of mould fungi on wooden materials depends mainly on the water activity (the air relative humidity), temperature, exposure time, presence of mould fungi and other organisms and the nutrient content of wood surface. In humidity exposures at RH above 80% (water activity above 0,8) of several weeks - months, the risk for the mould growth in pine and spruce sapwood exists when the temperature is between +5 and +50°C. Between -5 and +5°C, the growth of mould fungi is slow and possible only when the water activity is above 0,9. At water activity above 0.95 (RH 95%), the critical time for mould growth in wood is only some days, when temperature is between +25 and +45°C, and some weeks, when temperature is between +10 and +20°C. Within the same temperature and humidity conditions, the critical time for mould growth on nutrient rich wood is shorter than that of wood with low nutrient content In fluctuating humidity conditions when favourable and unfavourable conditions are alternating, the development of mould fungi is slower and the final rate of mould growth is lower as compared to the constant favourable condition
H Viitanen

Sapstain fungi associated with soft wood species in Kerala, India
1998 - IRG/WP 98-10260
Most of the packing case, plywood and match industries distributed throughout Kerala State, India utilise different timber species. The major problem in the utilisation of these species is their susceptibility to fungal sapstain and mould growth due to the conducive climatic conditions in the State. Several wood-based industries were surveyed and based on the economic importance and extent of sapstain damage, eight soft wood species were selected for the study. The results of the survey indicated that there was no definite pattern in the occurrence of mould and sapstain in different timber species collected from various wood industries in the State. Aspergillus spp., Penicillium spp. and Trichoderma viride were the dominant surface moulds growing on all timbers. Among the various timbers surveyed, Hevea brasiliensis, Mangifera indica and Alstonia scholaris had severe surface growth of different mould fungi. Memnoniella echinata was observed more commonly on H. brasiliensis than other timbers. Botryodiplodia theobromae was the dominant sapstain fungus causing bluish-black stain on surface as well as inside the wood. Ceratocystis fimbriata caused stain in Bombax ceiba, H. brasiliensis and M. indica; but heavy infection was found only on H. brasiliensis. The results of the survey also indicated that all the timber species were found to be susceptible to sapstain by B. theobromae; however, H. brasiliensis was most severely and frequently affected.
E J M Florence, J K Sharma, R Gnanaharan

Field tests with Antiblue and Biocide TT for the prevention of sapstain and mould fungi on Pinus elliottii timber
1992 - IRG/WP 92-3682
Freshly cut and sawn Pinus elliottii timber was dipped in four concentrations of Antiblue (active ingredient sodium pentachlorophenate) and Biucide TT (local substitute), at four immersion times and stacked in the open at Chisengu sawmill. Five weeks later, the timber was assessed for the incidence and intensity of stain and mould. The results showed that Antiblue was the better chemical providing 91% and complete control at 2% and 3% concentrations respectively. Biocide TT provided 74% control at a concentration of 8% and almost complete control at 12% concentration. The incidence and intensity of stain and mould was not affected by the immersion period
A J Masuka

Heat inactivation of mould fungi on wood
1993 - IRG/WP 93-40012
Heat treatments have been successfully used for eradication of dry rot. The effect of heat treatments at 40, 50 and 60°C for various time intervals on the inactivation of Penicillium brevicompactum was determined. The effect of heat on ungerminated spores and spores "pregerminated" for 24 hours was evaluated by plating on malt-extract agar. Although most ungerminated spores were inactivated after 5 h at 50°C, complete inactivation of ungerminated spores required 60°C for 30 h. Treatment at 60°C for 18 h inactivated the fungal mycelia on wood, as determined with ATP measurements.
J Bjurman

The susceptibility of acetylated Pinus radiata to mould and stain fungi
1992 - IRG/WP 92-1548
The aim of this investigation was to determine the effect of 5, 10, 15 and 20 percent acetylation weight gains on the susceptibility of Pinus radiata sapwood to mould and stain fungi, and to establish if an acrylic paint, an oil-based stain and a water repellant gave superior protection from fungal growth on wood treated to 20% acetylation weight gain, compared to untreated wood. One treatment set was tested using a modified anti-sapstain screening trial method, designed to give optimal conditions of relative humidity (>95%) and temperature (25°C) for mould growth. A second treatment set was exposed to the weather and assessed at 10, 21 and 40 weeks. The results showed that over the three week laboratory trial period, the rate of colonisation by mould fungi of Pinus radiata sapwood treated to 20% acetylation weight gain was significantly (P < 0.001) slower than on untreated wood. This was attributed to the lower availability of readily assimilated nutrients such as sugars and starch in acetylated wood. The rate of colonisation by mould fungi of acrylic-finished sapwood treated to 20% acetylation weight gain was significantly slower than on acrylic-finished untreated wood. Acetylation up to 20% weight gain conferred no protection from mould growth for test samples exposed to the weather. None of the finishes perfomed better on acetylated wood than non-acetylated wood when exposed to the weather.
R N Wakeling, D V Plackett, D R Cronshaw

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