AU2008205451B2 - Material and method for treatment of timber - Google Patents

Abstract

Abstract A material and method for treating timber. The material comprises a preservative and a carrier. The carrier is selected such that it remains mobile within the wood and provides for migration of the preservative within the treated wood. By providing a carrier which is mobile within the wood, the timber has a 'self healing' effect wherein the carrier/preservative migrates to any freshly cut or exposed surface of the wood to thereby redistribute and treat such a surface within the preservative and hence maintain integrity of a treatment envelope surrounding the wood.

Description

AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL Name of Applicant/s: Koppers Arch Wood Protection (Aust) Pty Limited Actual Inventor/s: Peter Raynor Soundy Cobham Address for Service is: SHELSTON IP 60 Margaret Street Telephone No: (02) 9777 1111 SYDNEY NSW 2000 Facsimile No. (02) 9241 4666 CCN: 3710000352 Attorney Code: SW Invention Title: MATERIAL AND METHOD FOR TREATMENT OF TIMBER Details of Original Application No. 2005201451 dated 06 Apr 2005 The following statement is a full description of this invention, including the best method of performing it known to me/us: File: 29754AUP03 -2 MATERIAL AND METHOD FOR TREAMENT OF TIMBER Related Application This application is a grandchild of AU 2002215690, which is herein 5 incorporated by reference in its entirety. Field of the Invention The present invention relates to preservatives and particularly preservatives for timber building materials. 10 Background of the Invention Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field. 15 Wood continues to be the most commonly used framing material for the construction of residential properties. Its weakness to termite attack in some countries has been lessened by treatment of wood with insecticides. Application methods and approved chemicals vary dramatically throughout the world. Softwood timbers, pinus radiata, pinus elliotti, and pinus carribea used as 20 framing timber is Australia are susceptible to termite attack. Changes to government regulations have limited the use of soil poisoning agents (banning of organo-cholride insecticides), which has led to a higher incidence of termite attack of timber framed houses. Many countries including Australia and the USA are struggling to find suitable 25 cost-effective methods to combat this ever-increasing risk of termite attack. One of the strategies to combat termite attack of softwood frames is the treatment of the timber with insecticides or more broad-spectrum wood preservatives. In Australia, for example, treatment of timber is covered by the Australian standard AS 1604-2000/. Hazard class H2 is defined for the biological hazard - borer 30 and termites. Retention is measured in mass/mass (%m/m). The approved chemicals are shown in the following table.

-3 Table I Minimum preservative retention in the penetration zone - Hazard Class 2 (H2) Waterborne Light organic solvent preservatives Copper chrome Ammoniacal copper Permethrin Cypermethrin Deltamethrin arsenic quaternary (CU+ Cr + As) (Cu + DDAC) 0.320 %m/m 0.35 %m/m 0.020 %m/m 0.030 %m/m .0020 %m/m Penetration is defined under the standard as: "All preservative-treated wood shall show evidence of distribution of the preservative in the penetration zone in accordance with 5 the following requirements: (a) If the species of timber used is of natural durability class 1 or 2, the preservative shall penetrate all the sapwood. Preservative penetration of the heartwood is not required; (b) If the species of timber used is of natural durability class 3 or 4, the preservative shall penetrate all of the sapwood and, in addition one of the following requirements shall apply: (i) Where the lesser cross-sectional dimension is 10 greater than 35 mm, the penetration shall be not less than 8 mm from any surface. Where the lesser cross-sectional dimension is equal or less than 35 mm, the penetration shall be not less than 5 mm from any surface; (ii) Unpenetrated heartwood shall be permitted, provided that it comprises less than 20% of the cross-section of the piece and does not extend more than halfway through the piece from one surface to the 15 opposite surface and does not exceed half the dimension of the side in the cross-section on which it occurs." In order to provide for penetration of the preservative, a carrier must be used. As shown in the Australian standard, the carriers currently available are waterborne or solvent borne systems. 20 Waterborne carriers swell wood and hence timber thus treated needs to be re dried prior to use in service. Australian Standards specify the maximum moisture content of pine framing. This level is around 12-14% moisture content. The process sequence is: Dry wood 4 treat - re-dry wood 25 Solvent borne preservatives because they are non-polar do not raise the moisture content and hence do not swell the wood. The process sequence is: Dry wood - solvent treat - 3a The disadvantage of this treatment is the high cost of solvents and potential environmental concerns with volatile organic compounds (VOC's) being released into the atmosphere. Application of the insecticides to wood is normally carried out by a batch process 5 involving a pressure vessel. For water-borne preservatives a vacuum pressure process (Bethell or full cell) is used. This ensures, providing the wood is dry, complete sapwood penetration and adequate heartwood penetration if required. For LOSP (light organic solvent preservatives) a double vacuum process ensures penetration to AS 1604-2000. 10 Pressure plants are expensive to construct, and being batch processes, conventional treatments do not match well with continuous sawmill production and require a high level of operator control to maintain costs. It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. 15 Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to". Although the invention will be described with reference to specific examples it 20 will be appreciated by those skilled in the art that the invention may be embodied in many other forms. Summary of the Invention According to a first aspect of the present invention there is provided a material 25 for treating wood comprising a preservative and a carrier, said material comprising: a preservative selected from an insecticide, termiticide, fungicide, mouldicide, or the like, or mixtures thereof, and a carrier within which said preservative is migratable, said carrier being selected such that it provides for "self healing" of a freshly cut or 30 exposed surface of said wood to thereby redistribute and treat such a surface with said preservative and hence maintain integrity in a treatment envelope, said carrier including: - 3b a drying oil selected from linseed oil; and an extender, selected from heating oil. According to a second aspect of the present invention there is provided a 5 method of treating wood, said method comprising contacting said wood with a material as defined according to the first aspect of the present invention. According to a third aspect of the present invention there is provided treated wood, when so-treated by a method as defined according to the second aspect of the present invention. 10 In one form, the present invention comprises a material for treating wood comprising a preservative and a carrier, the carrier remaining mobile within the wood such that it provides for migration of the preservative within the treated wood. In a further preferred embodiment, the carrier is a drying oil such as linseed oil or fish oil or any other drying oil, and may include extenders such as heating oil. These 15 carriers remain mobile in the wood for a considerable period of time thereby allowing for migration of the preservative. The quantity of extender can between 90 to 10% of the total carrier, preferably 30 to 70% and most preferably 40 to 60%. A wide variety of preservatives may also be used in combination with the carrier oil. Various insecticides and termidicides known in the art may be mixed with the oil 20 including synthetic pyrethroid, permethrin, cypermethrin, imidachloprid etc. Fungicides and mouldicides may also be used such as iodopropynylbutylcarbamate (IPBC), organic tin compounds such as tributyltin naphthenate (TBTN), organic copper compounds such as copper 8 quinolinolate and copper naphthenate, organic zinc compounds, quaternary ammonium compounds, 25 tertiary ammonium compounds, isothiazolones, triazoles such as tebuconazole, boron compounds. This would allow the treatment material to be used as a permanent preservative as defined by Hazard classes 3,4 and 5 in Australian Standard AS 1604 2000 America Wood Preservers Association (AWPA) standards (USA) and MP 3640 (New Zealand). 30 Drying agents such as cobalt, manganese, zirconium and copper naphthenate may be added to accelerate the drying of the drying oil.

-4 The amount of the preservative/active constituent in the treatment material depends upon the preservative effect required but is expected to be below 5%, preferably below 2% and in many cases most preferably below 1%. The applicant has found that the abgve mentioned material comprising a mixture 5 of preservative and 'mobile' carrier provides an effective wood preservative which has a 'self healing' effect. Since the carrier remains mobile within the wood, it is capable of redistributing the active components of the preservative. This redistribution or migration of the carrier/preservative mixture will generally occur preferentially along the grain of the wood, however, some distribution across the grain Will also occur. By providing 10 such a migratable material, it is not necessary for the ends of the timber to be retreated after cutting since the active components of the material will be provided to the freshly cut ends with the migrating carrier oil. Via this 'self healing' effect, the carrier/preservative migrates to any freshly cut or exposed surface of the wood to thereby redistribute and treat such a surface with the 15 preservative and hence maintain integrity of the treatment envelope. This is a significant advance over conventional preservative techniques. All previous techniques essentially treat the wood, are re-dried and then remain 'dormant' or fixed within the wood. The present inventive material and method provide a 'self healing' wood capable of retreating itself and in particular providing a preservative 20 treatment to cut or damaged surface areas, which of course are the most common entry for termites. Migration/penetration of the preservative system occurs in both radial and tangential directions forming an envelope around the treated wood. Such penetration in the tangential direction does not occur with water borne preservatives. Further, such 25 migration ensures a consistency of the envelope around the surface of the treated wood. The envelope may be formed in both the heartwood and the sapwood and the aforementioned 'self healing' phenomenon also preferably occurs in the heartwood and the sapwood. It will be recognised by persons skilled in the art that this self healing effect can be 30 influenced by a number of parameters, for instance different carriers have different mobilities within the wood. Certain carriers may dry more quickly than others. Accordingly, the self healing effect will not be indefinite but tests have shown that this -5 self healing effect will last from around a minimum of two to three weeks up to several months. In a second embodiment, the present invention provides a method of treating wood comprising contact the wood with a mixture of preservative and carrier, the career 5 remaining mobile within the wood such that it provides for migration of the preservative within the wood. The treatment step can be conducted using conventional pressure application techniques such as existing vacuum pressure systems known in light organic solvent plants. Alternatively, the applicant has also found the mixture of the preservative and 10 carrier can be anolied without the need for pressure application. Treatment can be accomplished by spraying, dipping etc which, unlike previous conventional batch systems, is ideal for use on continuous production line facilities such as saw mills. The applicant has also found that the proposed treatment material and method provides more than adequate protection without the need for complete. sapwood 15 penetration as required under the Australian Standard. To explain, in one embodiment a protective envelope of preservative/carrier oil mixture with a depth of around 5 mm can be provided by simple dipping or spraying. This 5 mm envelope provides more than adequate protection from termite attack and, as mentioned above, allows migration of the preservative longitudinally through a timber 20 board or beam to cover any end cuts. This of course is a major benefit over conventional techniques. As discussed earlier, the Australian standard requires that, irrespective of the species of timber, ie natural durability class I to 4, the preservative shall penetrate all sapwood. The present invention does not require penetration of all sapwood. It uses an 25 envelope type protection rather than penetration throughout the sapwood. This 5 mm envelope is a move away from conventional techniques but still provides adequate protection for treated timber and with the use of a preservative/mobile carrier oil results in the aforementioned self healing effect which of course is unknown with conventional techniques. 30 The most preferred carrier is linseed oil which is a drying oil, ie saturates in air. The linseed oil dries to form a water barrier and penetrates without the need for pressure. Advantageously, it is also low odour. Other drying oils such as fish oil may be used and -6 other light weight hydrocarbons, eg heating oil may be used in limited quantities as an extender to the linseed or fish oil in order to reduce costs. Another advantage of the. carrier oil is its high boiling point/flash point which reduces vapour emissions in production and use. 5 Another surprising benefit of using such a high boiling point carrier is its advantageous effect on migration of the preservative. To explain, it is believed that higher boiling point of the carrier/preservative mixture tends to allow the preservative to move inwards, as compared with more volatile solvents which migrate outwardly. Indeed, the extender can also have a beneficial effect on the migration of the 10 preservative. The extenders currently tested by the applicant have boiling poiits between about 175*C and 300*C. These extenders remain quite mobile within the wood. Preferably, the boiling point of the entire solvent/carrier system should remain above 62*C. While this is not essential it is preferred and suitable quantities of drying oils such as linseed or fish oil can be mixed with heating oil to obtain this boiling point. 15 Of course, using such a non-swelling drying carrier oil also has the advantage that the treated wood/timber does not need to be re-dried, ie treatment can be accomplished by simple dipping of the wood for periods of say up to one minute. Current trials with radiata and slash pine have both achieved 5 mm envelope penetration within about five to 60 seconds dipping time. 20 It is envisaged that other carrier oils may also be used provided, that when mixed with the preservative they remain mobile within the wood to allow migration of the preservative. Best Mode for Carrying Out the Invention Tests were conducted to verify the efficacy of the above mentioned process, 25 including the mobility and self healing characteristics of the preservative/carrier system previously described. Example 1 Radiata heartwood, radiata sapwood, slash heartwood and slash sapwood was sourced from various suppliers. Boards measuring 35 mm x 90 mm x 4.8 metres were 30 cut into four separate 1 metre lengths. Boards measuring 35 mi x 90 mm x 2.4 metres were cut into two separate 1 metre lengths. A drying oil (linseed oil) used in combination with an extender (heating oil) was used (ratio of linseed oil to extender 50:50). The -7 preservative formulation also had an addition of 0.01% (m/m) copper (present as copper naphthenate) as an indicator of the penetration. The test was conducted by firstly weighing the boards, and then dipping the board, in a mixture of the preservative formulation with 0.01% (m/m) copper (present as copper naphthenate) for 1 minute. 5 They were allowed to drip until dry to the touch. Boards were then weighed again and stacked for 24 hours before being cut in half. The exposed surface on one half of the board was sprayed with indicator solution and photographed. As shown in Table 2 resultant weights taken both before and after treatment show average uptakes for radiata heartwood at 18 /m 3 , 20 /m3 for radiata sapwood, 16 /m3 10 for slash heartwood and 18 i/m 3 for slash sapwood. Standard deviations were low and the coefficient of variation was less than 20 in all but the slash heartwood. This indicates that there is little variability in uptake of preservative into radiata heartwood and sapwood, and slash sapwood. Table 2 - Example 1: Uptake Results (60 Second Dip) Wood Type Uptake StDev Coeff of Var Radiata heartwood 17.89 3.5 19.67 Radiata sapwood 19.97 3.5 17.65 Slash heartwood 16.36 5.35 32.73 Slash sapwood 18.35 2.9 15.9 15 The attached figures show the effect of the treatment on radiata heartwood, radiata sapwood, slash heartwood and slash sapwood at various times after treatment as follows: Figures 1 to.4 show radiata heartwood, slash heartwood, radiata sapwood and slash sapwood respectively 24 hours after treatment, 20 Figures 5 to 8 are close ups of the cut surface of the material shown in figures 1 to 4 respectively, and Figures 9 to 12 show two stacks of the material, the lower stack being that shown in figures 1 to 4 and the other stacks being the same material 24 hours later. As shown in figures 1 to 4 and more clearly in figures 5 to 8, the inventive process 25 provided a consistent 5 mm envelope of penetration through the radiata heartwood, radiata sapwood and slash sapwood. A few of the slash heartwood samples did not show such a 5 mm envelope. All samples, however, showed the migration of the treatment material ('self healing' effect) 24 hours later. Figures 9 to 12 provide an excellent comparison of -8 mobility/penetration within 24 hours. Each figure has two stacks as mentioned above. The bottom stack is the material shown in figures 1 to 4. The top stack is the radiata/slash heartwood/sapwood 24 hours after end cuts. The increased penetration of the carrier/preservative is clearly evident. The migration of the treatment material and 5 self healing effect is most obvious in the radiata sapwood shown in figure 11 and radiata heartwood shown in figure 9. Example 2 In Example 1, the treatment process involved a 60 second dip. Trials with pinus elliotti (slash pine) have shown that treatment times can be reduced to as low as five 10 seconds without effecting penetration or retention. Treatment uptake depends on the profile used with rougher headed material giving uptakes 10 to 15% higher than smooth dress material. In addition, these trials have shown that packs can be treated in their final shape and form, ie tightly block strapped, without effecting uptake and penetration. 15 The table below shows the correlation between dipping time and average uptake. As is clear from this example,. dip times as low as five seconds can provide sufficient uptake of carrier/preservative mixture for efficient generation of the protective envelope. This is even true, as mentioned above, with packs of tightly strapped material. In this case packs of 95 x 45 mm timber were used stacked six high and five wide. 20 Table 3 - Example 2: Uptake Results (Dip time Variation) Species Profile Dip Time (sec) Average uptake %coeff of variation (1/m3) Slash Pine Rougher headed 60 25 28 Slash Pine Rougher headed 45 30 34 Slash Pine Rougher headed 30 26 32 Slash Pine Rougher headed 5 18 22 Slash Pine Rougher headed 5 17 21 Example 3 This example related to the treatment of Douglas fir. Douglas fir (psuedotsuga 25 menziesii) is an inherently difficult species to treat. Trials with this species using the above mentioned formulation have shown penetration in both the hardwood and sapwood similar to pine species. The treatment process involved a 60 second immersion in a preservative carrier mix, where the carrier was at 50:50 mix of linseed oil and heating oil.

-9 Average uptakes for 100 x 50 and 150 x 50 were around 20 L/m 3 . A well defined envelope was formed in both the heartwood and sapwood. Accordingly, it can be seen from this example that the inventive treatment may be applied to a wide variety of timber products. 5 Example 4 In addition to sawn timber, the treatment material and process is suitable for composite products. Treatment trials have been carried out with various wood composite to assist uptake and penetration, ie formation of the preservative envelope. Composites treated include particle board, plywood, medium density fibre board (MDF) 10 and oriented strand board (OSB). The treatment process was similar to the above, ie a 60 second immersion. Details over these tests are given under Table 3 Table 4 - Example 4: Uptake Results (Composite Products) Wood Type Uptake Std dev %CV Particle Board 29.4 6.2 21.1 Plywood 37.2 7.7 20.6 MDF 14.3 0.6 4.1 OSB 85.9 8.9 10.3 15 Example 5 The examples above were conducted using oil mixtures as the carrier. Tests have also being conducted using water-in-oil emulsions including up to 30% water. If desired, emulsifiers in the form of non-ionic surfactants can also be added to the emulsifier. 20 It has been found that such formulations gave similar envelopes of penetration with similar uptakes. Advantageously, wood swelling was minimal at these concentrations of water. Table 5 - Example 5: Uptake Results (Water in Oil Emulsion) Species Profile Dip Time (sec) Average uptake %coeff of variation (1/m3) Radiata pine Rougher headed 60 21 26 Radiata pine Rougher headed 30 19 22 Radiata pine Rougher headed 15 19 30 Radiata pine Rougher headed 5 15 2S 25 As can be seen from Table 5 above, using water in oil emulsions also give sufficient uptake of the carrier/preservative mixture to provide suitable treatment. It is -10 also noted that with water in oil emulsions, the uptake between five second dip times and 60 second tip times is even less than previous examples. Example 6 Further tests were conducted on the susceptibility of the treated blocks to termite 5 attack. Commercial-size-section (35 x 90 mm) material of both slash and radiata pine were treated with the described material and supplied as 1m lengths. One hundred and forty test blocks (35 x 90 x 190 mm long) were used; one block cut from each 1m length supplied. Twenty-eight treatments (including 16 with block ends treated) with 5 10 replicates were exposed in plastic food containers to termites foraging in trenches at. Beerburrum, south-east Queensland, Australia. Radiata pine control blocks were also exposed in plastic food containers to monitor termite foraging vigour on each trench. Following exposure for 29 weeks, mass losses of the blocks were estimated, analysed and reported. 15 On 3 of the 4 trenches, C. acinaciformis or Schedorhinotennes seclusus, or both provided a severe termite foraging pressure. Termites did not forage on the remaining trench, which had been used recently for other work and the absence of termites may have been a "carry-over" effect. We have not observed this phenomenon before. On the other trenches, the termites entered the vast majority of boxes, but essentially damaged 20 only untreated and solvent test blocks and feeder blocks (see Table). All treatments appeared to protect the test blocks. Exposing cut untreated ends to the termites did not promote termite foraging on these blocks and there appeared no need to treat the ends of the test blocks with treatment material, with regard to C. acinacifonnis. Industry, however, should be cognisant of differences in foraging behaviour between termite 25 genera, and perhaps between termite species, as the commercialisation of the envelope treatment processes develops. The below table outlines the results of these tests. The severity of the test protocol is evidenced by the amount of termite damage to the control blocks, (ie those treated with solvent only) in'the control boxes and by the amount of fungal decay in some of the 30 test boxes. The termite foraging pressure was severe and conditions suitable for sustained termite foraging and supportive of fungal decay.

Those blocks treated by the present invention, ie Penmethrin or Delta envelopes resisted both termite attack and fungal decay very well compared with conventional techniques, eg Permethrin, LOSP (light organic solvent preservative). The Delta/Permethrin compounds are conventional insecticides/ternidicides used 5 in Australia.

-12 Table 6: Summary of Termite Trial Box No. Species Heart/sap Treatment Test Feeder Trench I Radiata Heartwood Untreated Fail*** Fail *** 2' 0 Radiata. Heartwood -I6rmethrin envelope Pass Fai* 2 5~' Radina't Ietwood lOSlNPerniethriii Pass l all*** 2 22 Radiata Heartwood Permethrin envelope Pass Fail* 1 21 Radiata Heartwood Delta envelope Pass Fail* 1 8 IndiataveS'ap-ove .F:. -, .4 ;'9 ~ $Radia 'Sahvada elta.'e~elopj s } Box No. Species Heart/sap Treatment Test Feeder Trench 11 Slash Heartwood # Untreated Fail*** Fail*** 2 25 Slash Heartwood Permethrin envelope Pass Fail** 2 'Slash:. Hetwod !FbiiiOSajd iassf- ail 1 l!ash eeW oW iai r h iit 5Sash -a ob l a e e s f'ild 26 Slash Heartwood Delta envelope Pass Pass 1 16 Slash Sapwood Untreated Fail*** Fail*** 2 l'/ Slash S'pw6'd.@ (Pe 4 i'tliri hy i i v il .19' Slash asi~ ltt~ fe_6_______1__ 20 Slash Sapwood Permethrin LOSP Pass Fail** 2 23 Slash Sapwood Pernmethrin envelope Pass Fail** 4 24 Slash Sapwood Delta envelope Pass Fail* 4 Box No. Species Heart/sap Treatment Test Feeder Trench jjf33j QKadiata Hear oil6Q1ai* n N7 3 .4 2AIdiata Heare 6bil{ il e rf w .N/T4h A. iN N Radiati Sijwbod2jl Ahit da 1 dd ~N& 3~~NAf 27 Radiata Sapwood Permethrin envelope N/A N/A 3A 28 Radiata. Sapwood Delta envelope N/A N/A 3A 5 Mi A Test blocks with ends treated * Attacked ** Moderate attack * Severe attack 10 # High sapwood content A Lack of termite activity (trench had been used previously for boron trial) N/A Not Applicable 15 Additional tests were conducted on the various samples from Example 6 and they are provided under Figure 13. This test was to determine the permethrin retention in the outer 5 mm of the treated samples. As mentioned above, the disclosed treatment -13 provides an envelope around the timber which acts as a barrier to termite and fungal attack. The Australian Standard AS 1604 for insecticide/termidicide content is 0.02%. Samples 168A, 21 1A and 129B were control blends and hence were not treated with 5 permethrin. As can be seen from the remaining samples, however, most fell within or above the 0.02% standard (10% deviation). The Applicant's target was to treat only the outer 5 mm of the wood within the 0.02% permethrin retention. This is in contrast to the Australian Standard AS1604 which calls for complete sapwood penetration and in the case of radiata pine, 5 mm 10 heartwood penetration. The 5 mm envelope was achieved in both heartwood and sapwood of the radiata. For slash pine, where only sapwood penetration is required, a 5 mm envelope was also achieved. Accordingly, it can be seen that the inventive material and treatment method provide not only adequate protection but does so in a more efficient and cost effective 15 manner than conventional techniques. Industrial Applicability It can be seen that the present invention provides a significant advantage over the prior art. The aforementioned discussion should in now way limit the scope of the invention and various other embodiments can be provided without departing from the 20 spirit or scope of the invention.

Claims (20)

1. A material for treating wood comprising a preservative and a carrier, said material comprising: 5 a preservative selected from an insecticide, termiticide, fungicide, mouldicide, or the like, or mixtures thereof; and a carrier within which said preservative is migratable, said carrier being selected such that it provides for "self healing" of a freshly cut or exposed surface of said wood to thereby redistribute 10 and treat such a surface with said preservative and hence maintain integrity in a treatment envelope, said carrier including: a drying oil selected from linseed oil; and an extender, selected from heating oil. 15

2. A material according to claim 1, wherein said carrier remains mobile for up to three months.

3. A material according to claim 1 or claim 2, wherein said carrier remains mobile for up to two weeks. 20

4. A material according to any one of the preceding claims, wherein said carrier contains between 10 and 90% w/w of said extender.

5. A material according to any one of the preceding claims, wherein said 25 carrier contains between 40 and 60% w/w of said extender.

6. A material according to any one of the preceding claims, wherein the preservative is selected from the group consisting of synthetic pyrethroids, imidachloprid, iodopropynylbuthylcarbamate (IPBC), 30 organic tin compounds such as tributyltin naphthenate (TBTN), organic copper compounds such as copper-8-quinolinolate and copper - 15 naphthenate, organic zinc compounds, quaternary ammonium compounds, tertiary ammonium compounds, isothiazolones, azoles, triazoles and boron-containing compounds. 5

7. A material according to any one of the preceding claims, wherein the preservative content of the treatment material is below about 5% w/w.

8. A material according to any one of the preceding claims, wherein the preservative content of the treatment material is below about 2% w/w. 10

9. A material according to any one of the preceding claims, wherein the preservative content of the treatment material is below about 1% w/w.

10. A material according to any one of the preceding claims, wherein the 15 material for treating wood includes drying agents to accelerate drying of the drying oil.

11. A material according to claim 10, wherein the drying agent is selected from the group consisting of cobalt, manganese, zirconium, copper 20 naphthenate and mixtures thereof

12. A method of treating wood, said method comprising contacting said wood with a material as defined according to any one of the preceding claims. 25

13. A method according to claim 12, wherein said wood is contacted with said material by mean of pressure application, spraying, dipping, rolling, painting, or a combination thereof 30

14. A method according to claim 13, wherein said wood is dipped in said material from between around 5 seconds up to about 60 seconds. - 16

15. A method according to any one of claims 12 to 14, wherein the wood is contacted with a sufficient quantity of said material to provide an uptake of between about 10 to about 100 L/m 3 . 5

16. A method according to any one of claims 12 to 15, wherein the method is applied to radiata pine heartwood, radiata pine sapwood, slash pine (pinus elliotti) heartwood or sapwood, or Douglas fir (psuedotsuga menziesii) heartwood and sapwood. 10

17. A method according to any one of claims 12 to 16, wherein said wood is a wood composite selected from the group consisting of particle board, plywood, medium density fibreboard (MDF) and oriented strand board (OSB). 15

18. Treated wood, when so-treated by a method as defined according to any one of claims 12 to 17.

19. A material according to claim 1, said material substantially as herein 20 described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples.

20. A method according to claim 12, said method substantially as herein described with reference to any one of the embodiments of the 25 invention illustrated in the accompanying drawings and/or examples. Dated this 16 Ih day of November 2011 Shelston IP 30 Attorneys for the Applicant