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Forestry Science Protecting wood in service – performance without the downside Dr Michael J Kennedy Horticulture & Forestry Science, DPI&F 80 Meiers Rd,

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Presentation on theme: "Forestry Science Protecting wood in service – performance without the downside Dr Michael J Kennedy Horticulture & Forestry Science, DPI&F 80 Meiers Rd,"— Presentation transcript:

1 Forestry Science Protecting wood in service – performance without the downside Dr Michael J Kennedy Horticulture & Forestry Science, DPI&F 80 Meiers Rd, Indooroopilly QLD 4068 IAWS 2006 Meeting, Melbourne, November 13-16, 2006

2 Forestry Science Protecting wood in service – performance without the downside Why? Addresses global energy & carbon balance problems: Sequesters carbon as it grows Stores carbon indefinitely in service (if protected) Processing is energetically frugal (unless transported long distances) But! Timber harvesting from native forests ceased Native forest cannot be cleared for plantations Plantation water use must not endanger rivers & aquifers Natural biodegradability must be countered in service Protection systems must be harmless to environment Wood in 2100 – the renewable structural material sans pareil

3 Forestry Science Protecting wood in service – performance without the downside Timber harvesting from native forests ceased Native forest cannot be cleared for plantations

4 Forestry Science Protecting wood in service – performance without the downside Plantation water use must not rob rivers & aquifers

5 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

6 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment McCormick & Baxter Lumber Treatment site, Stockton, CA creosote & pentachlorophenol treatment of poles & ties

7 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

8 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

9 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

10 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

11 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

12 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

13 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

14 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

15 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

16 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

17 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

18 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

19 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

20 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

21 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

22 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

23 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

24 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

25 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment

26 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment 2500BC - crude pitch (on specified durable timber) 50AD - essential oils of cedar, juniper, valeriana mercuric chloride sodium arsenite copper sulphate zinc chloride coal tar creosote (& from 1965, fortified with insecticides) fluorides (& from 1909 mixed with dinitrophenol, dichromate..) copper naphthenate borates ammoniacal copper arsenite CCA (chromated copper arsenate) Biocidal systems used as wood preservatives

27 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment chlorophenols (TCP, PCP, + metal salts of these) lindane, DDT heptachlor, aldrin, dieldrin bis (tri-n-butyltin) oxide (TBTO) synthetic pyrethroids (permethrin, deltamethrin, cypermethrin, bifenthrin..) tri-n-butyltin naphthenate (TBTN) ammoniacal copper quaternary (Cu + DDAC) - ‘ACQ’ triazole fungicides (azaconazole, tebuconazole, propiconazole, cyproconazole) copper triazole (Cu + tebuconazole) - ‘CuAzole’ Non-metallic LOSP treatments (propiconazole + tebuconazole + permethrin) Biocidal systems used as wood preservatives CCA (chromated copper arsenate)

28 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment Dose ratePersistence in soil 1850 – arsenic trioxide 0.035infinite aldrin, dieldrin yrs 1975 – permethrin0.021 yr 1985 – deltamethrin months Diminishing environmental threat of wood preservatives e.g. termiticides

29 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment H1 & H2 (borers & termites, protected from weather): synthetic pyrethroids (permethrin, bifenthrin) H3 (insects & decay, exposed to weather, out of ground): Waterborne: ACQ (Cu + DDAC) Cu Azole (Cu + tebuconazole) LOSP: Non-metallic (triazoles + pyrethroid) H4 & H5 (all risks, in ground): Waterborne: CCA ACQ Cu Azole H6 (marine): Creosote + CCA dual treatment Current state of the art for biocidal wood preservatives

30 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment Heat treatments ( °C, under N 2 ) Heat denatures wood components utilised by fungi According to the amount of heat applied: Durability against fungi increases Strength decreases Resistance to termites decreases Hot oil treatments ( °C ) Some denaturation, but less than with the ‘dry’ heat treatments Oil imparts resistance to wetting and further improves durability Chemical modification of wood components (e.g. with acetic anhydride) Modified wood components cannot be utilised by organisms These ‘ultimate’ non-biocidal treatments are very expensive,.. commercial? Current state of the art for non biocidal wood preservation

31 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment Envelope impregnation (insects only) Spray or dip systems achieve protective envelope of pyrethroid (2-5mm) Cost effective, suitable for treating ‘final form’ timber Current state of the art for impregnation systems

32 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment Glueline addition (insects only) Stable pyrethroid in adhesive survives pressing process in plywood Bifenthrin is locked into the glueline, inaccessible to all but termites Very cost effective Current state of the art for impregnation systems

33 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment Waterborne impregnation (general purpose, CCA, ACQ, CuAzole) Low treatment cost (solvent is water) Wood swells and must be re-seasoned before dressing to final form Planer shavings are contaminated with preservative components The current preservatives contain metal (but it is ‘only Cu’) Cu is less well fixed in ACQ and CuAzole than in CCA treatments ACQ and CuAzole are 15-30% more expensive than CCA Current state of the art for impregnation systems

34 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment LOSP impregnation (white spirit etc solvent) Does not swell the timber, no re-seasoning or dressing required after, suitable for treating ‘final form’ timber Currently using dual triazoles + permethrin, excellent non-metallic system Does not penetrate some non-durable heartwood well (e.g. radiata pine) L/m 3 of solvent retained in timber after treatment, lost to air - likely near-future regulatory problems with VOC emissions, future is not bright Current state of the art for impregnation systems

35 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment Supercritical CO 2 impregnation (1 plant only - in Denmark) No swelling, no re-seasoning, no re-dressing, treating ‘final form’ timber Currently using dual triazoles + permethrin, excellent non-metallic system Closed system recycles CO 2 solvent - no solvent costs, no VOC emitted! Packs can be impregnated without spacers, wrapped! Timber can be painted immediately after impregnation All LOSP benefits without LOSP disadvantages - is this ‘IT’? Current state of the art for impregnation systems

36 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment Unfortunately, NO Plant operates at VERY high pressure - huge capital cost: (80M DKK for 60,000 m 3 /yr throughput) Operating pressures tend to damage timber Cannot deliver in-ground preservatives at present (H1, H2, H3 only) Current state of the art for impregnation systems Supercritical CO 2 impregnation - is this ‘IT’?

37 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment Supercritical CO 2 impregnation - is this ‘IT’? Current state of the art for impregnation systems

38 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment The next state of the art for impregnation systems?? (WO/2006/092673) IMPREGNATION APPARATUS AND METHOD Currently under development in Australia Uses compressed gases as carrier solvent, at current treatment plant pressures Achieves full penetration of radiata pine heartwood, at same retention as sapwood Initial work with spruce looks good ‘100%’ recovery of solvent from timber Possibility of sequential treatments …

39 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment So, well before 2100, we will have: Non-biocidal wood modification systems partially reducing the inherent susceptibility of timber to W.D.O.s without seriously diminishing desirable timber properties Supplementary biocidal treatments that.. use biocides presenting no threat to the environment are applied in closed systems that release no solvent and require no dressing after, no contaminated shavings

40 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment 1. For non-biocidal wood modification systems: Find the right balance between non-biocidal and biocidal for the most effective protection, the least reduction in other wood properties and the least release to the environment Develop simple measures of the quality of the non- biocidal treatment – ‘process’ specifications are not enough – we need verifiable results-type specifications that can be applied in the marketplace To achieve this, we need R&D:

41 Forestry Science Protecting wood in service – performance without the downside Protection systems must be harmless to environment 2. For the biocidal supplementation systems: Develop current excellent ‘above ground’ mixtures of low environmental impact biocides to produce combinations capable of protecting ‘in ground’ Develop penetration disclosing tests for the new generation organic biocides, to facilitate in-plant quality control of the treatment process To achieve this, we need R&D:

42 Forestry Science Protecting wood in service – performance without the downside


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