AU2013248255B2 - A Wood Treatment Method and Apparatus - Google Patents

Abstract

Abstract According to the present invention there is provided in a timber dip treatment process, rotation of immersed timber about two or more planes, thereby to actively expel air bubbles from said immersed timber and to facilitate the treatment solution getting between closely packed boards within a timber pack, thereby to relatively optimise the surface area of timber available to the treatment solution and thereby to relatively optimise the coverage of the preservative over the surface of the treated wood. (Figure 1) -3/5

Description

A WOOD TREATMENT METHOD AND APPARATUS Field of the Invention

The present invention relates to the treatment of wood/timber products and other cellulosic formulations with a preservative formulation. More specifically, the invention relates to the treatment of wood using an inventive, relatively optimised dipping process.

The invention has been developed primarily for use in treating timber packs via a dipping operation so as to relatively minimise “dry patches” on the treated wood; these are areas left untreated after the dipping operation. Although the invention will be described hereinafter with reference to this application, it will be appreciated that it is not limited to this particular field of use.

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 the common general knowledge in the field.

Wood is a staple construction material used throughout the world.

However, it is prone to degradation from elements including the natural environment, weather events, insects, rot and fire. Accordingly, a range of chemical treatments has been developed to improve the durability and working lifetime of wooden structures.

The treatment of timber or timber products with preservative compounds involves the introduction of stable chemicals into the cellular structure of the timber. This, in turn, protects the timber from hazards such as fungi, insects and other wood-destroying organisms. Preservative treatments may also include the introduction of chemicals that improve resistance to degradation by fire.

To treat and prevent infestations, timber is often impregnated or surface-coated with a preservative such as a fungicide or insecticide. The preservative is typically present in a carrier, with the mixture being applied to the surface of the timber, for example by dipping, spraying, brushing or pressure treatment, such that the carrier and preservative are absorbed into or coated onto the timber. Dipping consists of simply immersing the wood in a bath of one or more preselected preservatives for a period of time. Similar penetrations to that of brushing and spraying processes are achieved. Dipping obviously has the advantage of minimising hand labour relative to brushing or rolling.

In Australia, the treatment of sawn timber is covered by the Australian Standard “AS 1604.1-2012”. The present invention is especially applicable to Hazard Classes HI, H2, H2F, as well as antisapstain treatments of wood. Of these, Hazard Class H2 is defined for borer and termites. Although the present invention is exemplified with respect to H2F requirements, it will be readily appreciated by those skilled in the art that the invention is equally applicable to HI and H2 requirements and penetration standards and/or for antisapstain treatments. The approved chemicals are shown in the following tables (retention is measured in w/w [% m/m]).

Table 1

Minimum preservative retention in the penetration zone, H2 1 Copper, chromium arsenic (Cu + Cr + As).

2 Copper quat formulations, refer to Table B3, Appendix B of AS 1604.1-2012, where DDAX is didecyldimethylammonium chloride or carbonate/bicarbonate. 3 Copper azole formulations, refer to paragraph B4, Appendix B of AS 1604.1-2012, where azole is tebuconazole or 1:1 mixture of tebuconazole and propiconazole. 4 Boron compounds, expressed as elemental boron. To be used south of the Tropic of Capricorn, only.

Table 2

Minimum preservative retention in the penetration zone, H2F (H2F)

“Penetrated from each surface, excluding ends “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 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; (bi) Where the lesser cross-sectional dimension is 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; and (bii) 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 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 Standards, the carriers presently available can be characterised broadly as “waterborne” or “solventborne” systems. A carrier must be capable of providing sufficient penetration of the preservative into the wood, thereby to provide an effective barrier against infestation. Other considerations in the choice of carrier include the desired rate of penetration, cost, environmental, health and safety considerations. A carrier may provide for a “complete penetration”, an “envelope penetration”, or a “surface treatment” formulation in which a defined migration of one or more preservatives into or onto the wood is achieved. Impregnation procedures for timber have usually involved an impregnation procedure where the active agent is carried in a liquid carrier. Sometimes the liquid carrier is water or water based. Alternatively, the liquid carrier may comprise an organic or inorganic solvent.

The preservatives commonly used in timber treatment can be characterised according to the carrier vehicle used to carry preservatives into the timber, and by the active chemicals protecting against the various hazards. Water-based systems typically require a significant uptake of any water-based treatment composition in order to provide the required penetration through to the core of the timber. This results in an increase of the moisture content of the timber, which in turn affects the dimensional stability of the timber and may also require that the timber be redried prior to use.

Dip plants have been used for many years to cover the surface of timber with timber preservatives. However, best industry practice, for obvious efficiency reasons, is not to dip single pieces of wood. Rather, the untreated wood arrives at the treatment station in “packs”, i.e., with the individual pieces of wood bundled and tied tightly so as to facilitate space efficiency, ease of stacking, etc.

When dipping whole packs of timber, it can be difficult to ensure full coverage of timber. Air bubbles can be retained within the pack; these cause “dry patches”, which are areas of untreated wood, after the dipping operation. With reference to the photograph provided in Figure 1 of the accompanying drawings, the dry patches (i.e., those where the [coloured] preservative has not made contact with the surface of the wood) are clearly distinguishable.

Smooth dressed timber surfaces may also be pressed tightly together in specific locations within packs, such that the preservative liquid cannot readily migrate between the boards. The dry patches can vary in size, from being quite small (e.g., the size of an Australian fifty-cent coin, i.e., 2-3 cm in diameter), through to being relatively large (in the example shown in Figure 1 of the drawings, the dry patches were approximately 80 mm wide x 400 mm long).

Present dipping technology is limited to either: a) immersion without rotation; or b) rotation about one axis from above the liquid level. These methods do not provide rapid clearance of bubbles and physical movement of liquids between the wood surfaces undergoing treatment. These methods require the timber packs to be immersed for relatively long periods of time. Longer dipping periods in water-based preservatives give rise to additional swelling of the wood and delays in production. With solvent-based preservatives, longer dipping times can give rise to unnecessarily high uptakes, thereby increasing the cost of the treatment. Sometimes, even with long immersion times, some of the timber surface remains unprotected (i.e., not treated with the preservative) as, for instance, air bubbles can become trapped within a pack indefinitely, or the movement of the preservative liquid is restricted for the duration of the treatment. By clearing bubbles sooner, or enabling movement of the preservative liquid, shorter immersion periods may be facilitated whilst at once obtaining substantially full coverage of the preservative solution. With water-based preservatives, quicker immersion results in less swelling of the wood - and less required drying. Production rates can be greater due to less time required for dipping.

European patent No. EP 0 112 070 Bl, to Hickson’s Timber Products Limited, discloses an apparatus for applying treatment liquid, by dipping, to a batch of timber comprising pieces with flat faces engaged together face to face, comprising a container for treatment liquid and a support for said timber batch, the support being movable relative to the container between a timber receiving position, in which it is arranged to receive a said timber batch with said interengaged faces substantially horizontal, and a dipping position in which the timber batch on the support is located in the said container with said faces at a substantial angle to the horizontal, characterised in that said container is open topped so that dipping is carried out at atmospheric pressure, and in that the support comprises a cradle pivotally mounted relative to the open topped container for movement into and out of the latter through an arc.

The objective technical problem addressed by the present invention is therefore, if rotation about one axis was known already, why has nobody rotated the wood about two axes until now? The answer may be that until the time of the present invention, nobody had really noticed the problem. At the time of recognising the problem, the present Applicant was dip-treating wood using a bright blue pigment in the treatment solution. This caused any dry patches to stand out noticeably. The Applicant thereby sought to address this problem. Rotation about either axis appears to work adequately when used in conjunction with a relatively long (e.g., 10 minute) dip time. However, it is problematic from the perspective that in order to achieve this, one must either remove all the straps on the packs or replace them with a relatively loose strap.

From an operational point of view, whilst dry patches may not always be visible to the consumer (i.e., in cases where the treatment solution is uncoloured), wood containing dry patches is at greater risk of attack and biodegradation by insects and decay fungi than treated wood where all the surfaces have been adequately contacted by the preservative. This may result in product returns and a diminution in the reputation of the operator/supplier who has treated the wood in the first instance.

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. The present invention thereby seeks to provide a method for dip-treating wood whereby dry patches - areas of wood that do not get exposed to the treatment solution, are relatively minimised. The present invention seeks to improve the quality of treatment by reducing the number and size of dry patches that occur in dip-treated packs of timber, thus ensuring relatively increased exposure of the preservative to all surfaces of every piece of timber.

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 will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

The terms “wood” and “timber” are synonymous in the relevant art - and are used interchangeably throughout the present specification.

Summary of the Invention

The commercial context of the present invention is summarised below: Currently it takes up to around 10 minutes to dip-treat a wood pack with the straps removed. The Applicant seeks to achieve a similar result in around 5 minutes -and with at least some of the straps still attached.

The extent of successful treatment is thereby a function both of dip time and the ability to remove air bubbles. For instance, if wood packs were dipped for a relatively “long” period (e.g., the 10 minutes presently employed), then it is likely that substantially complete coverage of the wood would be achieved as most air bubbles would be dissipate naturally. In other words, as the dip period increases, so too does the coverage. However, the longer the dip period, the less the operational efficiency of the overall process will be.

One form of the present invention is a method of treating wood. Broadly, in a dip-treatment process, the timber is moved about two axes of rotation whilst immersed, thus providing a means to rapidly discharge substantially all air bubbles and facilitate movement of the preservative liquid throughout the pack of timber.

With the decrease in the amount of air bubbles comes an increase in the “available” surface area of the wood, which leads to better coverage by the preservative mixture.

Accordingly, with reference to Figure 2 of the accompanying drawings, the present invention is characterised by the ability to rotate timber packs in two axes of rotation whilst immersed. In general, the process is as follows: A timber pack is loaded into the dipping machine and lowered into the liquid preservative, i.e., the pack is lowered in the plane defined by the V and L axes. Once fully immersed, the pack is raised and lowered from each end (i.e., rocked longitudinally in a vertical plane about axis A) to help clear at least some of the air bubbles. The pack is then rotated through about 45 degrees (i.e., about the longest axis L) and the rotation procedure is repeated (i.e., up and down from each end). Further bubbles are expelled; and further penetration of the liquid preservative into the timber pack is achieved. The pack is then rotated to 90 degrees about axis L and again the longitudinal rotation is applied. Still further movement of liquid within the pack is facilitated. If necessary, the above process may be repeated.

Using the inventive process, it has been found that largely equivalent results can be obtained compared with those of regular (prior art) industry dip-treating practises, in around half the time, and potentially with the straps left on the wood packs.

According to a first aspect of the present invention there is provided a method of treating timber, said method comprising the steps of: providing a treatment vessel, said vessel comprising an effective volume of a timber preservative treatment solution; providing immersion means by which said timber may be operatively associated with said treatment vessel; associating said timber with said immersion means; immersing said timber within said treatment vessel via said immersion means, wherein the total immersion time is from around 2 minutes to around 10 minutes; rotating said timber about two or more axes, thereby to actively facilitate movement of the preservative about said timber, thereby to relatively optimise the surface area of timber available to said treatment solution; removing said timber from said treatment vessel, thereby to provide treated timber, thereby to treat said timber in accordance with the Australian H2F Standard, AS 1604.1-2012.

The inventive method is preferably adapted to treat packs of untreated timber. Preferably, the rotation sequence comprises rotating said timber about two or more axes comprises the following sequence: once fully immersed, the pack is rotated up to about 45 degrees (i.e., about the shortest axis) and the pack is raised and lowered from each end (i.e., rotated longitudinally) to expel at least some bubbles; the pack is then rotated to about 90 degrees and the longitudinal rotation procedure is repeated (i.e., up and down from each end), thereby to expel yet more bubbles.

The rotation sequence preferably comprises an optional initial expulsion of air bubbles wherein following immersion, the timber is raised and lowered from each end {i.e., rotated longitudinally in a vertical plane) to expel at least some bubbles.

In another embodiment, the total immersion time is around 5 minutes. In an embodiment, the timber is packed {i.e., the method is performed upon a pack of timber rather than individual pieces) and at least substantially tied during the immersion step.

Preferably, the preservative or mixture of preservatives is selected from the group consisting of: insecticides, termiticides, fungicides, mouldicides, or the like, and mixtures thereof. Preferred preservatives include, but are not restricted to synthetic pyrethroids (such as allethrin, bifenthrin, bioallethrin, cyhalothrin, cypermethrin, alpha-cypermethrin, beta-cypermethrin, cyphenothrin, deltamethrin, etofenprox, fenvalerate, permethrin, prallethrin, profulthrin, resmethrin, silafluofen, sumithrin, tetramethrin, tralomethrin, transfluthrin, imiprothrin), and other compounds such as acetamiprid, alkybenzyldimethyklammonium chloride (BAC) and other quaternary ammonium compounds, azaconazole, borates (such as borax or disodium octaborate) or boric acid, chlorfenapyr, chlorothalonil, chlorpyrifos, clothianidin, copper naphthenate and other copper soaps, copper oxine, cyproconazole, didecyldimethylammonium carbonate/bicarbonate, didecyldimethylammonium chloride, fipronil, flonicamid, imidachloprid, indoxacarb, iodopropynylbuthylcarbamate (IPBC), isothiazolones (such as benzisothiazolinone (BIT), butylbenzisothiazolinone (BBIT), chloromethylisothiazolinone (CMIT), dichlorooctylisothiazolinone (DCOIT), methylisothiazobnone (MIT), octylisothiazolinone (OIT)), nitenpyram, propiconazole, pyrethrins, tebuconazole, thiabendazole, thiachloprid, thiamethoxam zinc naphthenate, other zinc soaps; and mixtures thereof.

Preferably, the preservative treatment solution is a water-based antisapstain water formulation.

In an embodiment, the treated wood is classifiable in the art as “dry after” (moisture content <15% w/w) following treatment.

In an embodiment, by result, the quality of treated wood is approximately equivalent to that treated by prior art means (e.g., approximate 10 minute immersion, loosened or removed ties/straps).

According to a second aspect of the present invention there is provided an apparatus when used for treating timber in accordance with the Australian H2F Standard, AS 1604.1-2012, said apparatus comprising: a treatment vessel; immersion means by which said timber may be operatively associated with said treatment vessel over a period of from around 2 minutes to around 10 minutes; rotation means for rotating said timber about two or more axes, thereby to actively expel air bubbles from said timber and to facilitate the movement of said preservative about said timber, thereby to relatively optimise the surface area of timber available to said treatment solution; and means for removing said timber from said treatment vessel.

In an embodiment, the vessel comprises a predetermined (effective) volume of a timber preservative treatment solution.

In an embodiment, the immersion means is an automated hydraulic system associated with an automatic control unit. In another embodiment, the immersion means is integral with said rotation means.

According to a third aspect of the invention there is provided in a timber dip treatment process, an improvement comprising rotation of immersed timber, over a total immersion time of from around 2 minutes to around 10 minutes, about two or more axes, thereby to actively expel air bubbles from said immersed timber and to facilitate the movement of said preservative about said timber, thereby to relatively optimise the surface area of timber available to the treatment solution, and thereby to relatively optimise the quality and/or coverage of the so-treated timber, wherein said timber is treated in accordance with the Australian H2F Standard, AS 1604.1-2012.

According to a fourth aspect of the present invention there is provided treated timber, when so-treated by a method according to the first aspect of the invention.

Brief Description of the Drawings

With reference to Figures 3 to 8 of the accompanying drawings, the treatment vessel (1) comprises a timber preservative solution (2) filled to a level (3) which is sufficient to enable the timber to be dipped and remain largely submerged for the duration of the dip schedule; the precise volume is not important, although for efficiency reasons, overflow should be avoided. The immersion means is a hydraulic lift (4) which is associated with an automatic SPS control unit (not shown). The timber pack (5) is shown operatively associated with the immersion means (4). A preferred embodiment of the invention will now be described with reference to the accompanying Figures, in which:

Figure 1 is a photographic depiction of dry patches (7); these can be clearly seen is this example, where a coloured treatment solution has been used. The dry patches are clearly susceptible to insecticidal or fungicidal attack following the treatment process.

Figure 2 is a representation of the various planes of through which a timber pack is rotated in the process of the present invention. For instance, the pack is lowered in the plane defined by the V and L axes. Once fully immersed, the pack is raised and lowered from each end (i.e., rocked longitudinally in a vertical plane about axis A) to help clear at least some of the air bubbles. The pack is then rotated through about 45 degrees (i.e., about the longest axis L) and the rotation procedure is repeated (i.e., up and down from each end). Further bubbles are expelled; and further penetration of the liquid preservative into the timber pack is achieved. The pack is then rotated to 90 degrees about axis L and again the longitudinal rotation is applied. Still further movement of liquid within the pack is facilitated. If necessary, the above process may be repeated. Therefore, in general, lifting and lowering vertically is along the V axis; rotation is around axis A, along with raising and lowering along axis V, effective in dispelling air from within pack; and rotation around axis L, by up to 90 degrees, is effective in dispelling air from within pack.

Figure 3 shows the timber pack (5) operatively associated with the immersion means (4) immediately prior to immersion within the treatment vessel (1).

Figure 4 shows the timber pack (5) fully immersed within the treatment vessel (1). At this stage, air bubbles (6), shown only on the underside of the timber pack, but resident throughout the pack will be apparent. These air bubbles prevent the treatment solution (2) from contacting with all surfaces of the wood (5). Optionally, the wood is then “rocked” such that it may be respectively raised and lowered from each end (i.e., rotated longitudinally in a vertical plane) to help clear some of the bubbles. This shaking process is not depicted in the drawings.

Figure 5 shows the timber pack (5) having been rotated through 45 degrees (i.e., about the shortest axis) and the longitudinal rotation procedure described in respect of Figure 4, above, is repeated (i.e., up and down from each end). This clears even more air bubbles. The air bubbles (6) are not shown in this Figure, however, it will be appreciated that some (less than were present in Figure 2) still reside within and on the surface of the wood pack.

Figure 6 shows the timber pack (5) having been rotated to 90 degrees and the longitudinal rotation procedure described in respect of Figure 4, above, is repeated (i.e., up and down from each end). This clears yet more air bubbles, which are once again not shown in this Figure for clarity reasons.

Figure 7 shows the timber pack (5) having been returned to the horizontal prior to removal; and

Figure 8 shows the timber pack (5) having been removed from the treatment vessel (1). At this point, it may be suspended for a few seconds through to a few minutes to allow excess treatment solution to run or drip off under gravity. Optionally, the above-described longitudinal rotation procedure may be employed to aid in returning treatment solution to the treatment vessel. As was known from the prior art, the precise drainage time is a trade off between the desire to return as much treatment solution as possible to the treatment vessel (1) and the need to begin treating the next pack of wood.

Example 1 A “conventional” dipping treatment was undertaken. This involved loading the wood pack onto the immersion apparatus, removing the straps from the pack, and immersing the unstrapped wood for a period of approximately 10 minutes in a preservative treatment solution suitable for H2F treatment of the wood.

The wood pack was then removed, drained and assessed. Several dry patches (7) were observed, ranging from around 3 cm in diameter to around 0.5 m in length. This defines the “conventional” standard against which the present invention is assessed; only a few dry patches, but with the straps having been removed/loosened and a relatively long tip time.

Example 2

Treatment was undertaken as per Example 1, but with the straps intact. The dip period was 10 minutes. The wood pack was then removed, drained and assessed. Twenty-to-thirty dry patches (7) were observed, ranging from around 3 cm in diameter to around 0.5 m in length.

Example 2 shows that the convenience of leaving the straps on has an adverse effect on the extent of the overall wood treatment.

Example 3

Treatment was undertaken as per Example 1, with the straps removed or loosened. However, the dip period was 5 minutes. The wood pack was then removed, drained and assessed. Twenty-to-thirty dry patches (7) were observed, ranging from around 3 cm in diameter to around 0.5 m in length.

Example 3 shows that a lesser dip time/immersion period has an adverse effect on the extent of the overall wood treatment.

Example 4

Treatment was undertaken as per Example 1, but with the straps intact. The dip period was 5 minutes.

The inventive dual rotation process was applied to the dipped wood, i.e., rotating said timber about two or more axes, thereby to actively expel air bubbles from said timber, thereby to relatively optimise the surface area of timber available to said treatment solution. The following rotation sequence was utilised: Once fully immersed, the pack is rotated about 45 degrees (i.e., about the shortest axis) and the pack is raised and lowered from each end (i.e., rotated longitudinally) to expel at least some bubbles; the pack is then rotated to about 90 degrees and the longitudinal rotation procedure is repeated (i.e., up and down from each end), thereby to expel yet more bubbles.

The wood pack was then removed, drained and assessed. The number of dry patches observed was substantially less than in Example 1, and their size, on average, was significantly smaller than in Example 1.

The result of Example 4 was comparable to that of Example 1, showing that the convenience of leaving the straps on - and the convenience of shorter dip periods can be substantially overcome using the inventive dual-rotation process.

Example 5

Treatment was undertaken as per Example 4, but with the straps removed. The dip period was 5 minutes. The inventive dual rotation process was used, i.e., rotating said timber about two or more axes, thereby to actively expel air bubbles from said timber, thereby to relatively optimise the surface area of timber available to the treatment solution.

The wood pack was then removed, drained and assessed. Very few, if indeed any “dry patches” were observed.

Example 5 provides a means for treating substantially the entirety of the surface area of a wood pack, in only 5 minutes, using a dual-rotation process.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description. Thus, while there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognise that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as fall within the scope of the invention. For example, any formulas given above are merely representative of procedures that may be used. Steps may be added or deleted to methods described within the scope of the present invention.

Although the invention has been described with reference to specific examples it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims (20)

1. THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

   1. A method of treating timber, said method comprising the steps of: providing a treatment vessel, said vessel comprising an effective volume of a timber preservative treatment solution; providing immersion means by which said timber may be operatively associated with said treatment vessel; associating said timber with said immersion means; immersing said timber within said treatment vessel via said immersion means, wherein the total immersion time is from around 2 minutes to around 10 minutes; rotating said timber about two or more axes, thereby to actively facilitate movement of the preservative about said timber, thereby to relatively optimise the surface area of timber available to said treatment solution; removing said timber from said treatment vessel, thereby to provide treated timber, thereby to treat said timber in accordance with the Australian H2F Standard, AS 1604.1-2012.
2. 2. A method according to claim 1, adapted to treat packs of untreated timber.
3. 3. A method according to claim 2, wherein rotating said timber about two or more axes comprises the following sequence: once fully immersed, the pack is rotated through up to about 45 degrees (i.e., about the shortest axis) and the pack is raised and lowered from each end (i.e., rotated longitudinally) to expel at least some bubbles and to facilitate movement of the preservative about the timber; the pack is then rotated to about 90 degrees and the longitudinal rotation procedure is repeated (i.e., up and down from each end).
4. 4. A method according to claim 3, comprising an optional initial expulsion of air bubbles wherein following immersion, the timber is raised and lowered from each end (i.e., rotated longitudinally in a vertical plane) to expel at least some air bubbles in an initial purge.
5. 5. A method according to any one of the preceding claims, wherein the total immersion time is around 5 minutes.
6. 6. A method according to any one of the preceding claims, wherein said timber is packed (i.e., the method is performed upon a pack of timber rather than individual pieces) and at least substantially tied during the immersion step.
7. 7. A method according to any one of the preceding claims, wherein the preservative treatment solution is an antisapstain water based formulation.
8. 8. A method according to any one of the preceding claims, wherein said preservative is selected from the group consisting of: insecticides, termiticides, fungicides, mouldicides, or the like, and mixtures thereof.
9. 9. A method according to claim 8, wherein said preservative is selected from the group consisting of: synthetic pyrethroids (such as allethrin, bifenthrin, bioallethrin, cyhalothrin, cypermethrin, alpha-cypermethrin, beta-cypermethrin, cyphenothrin, deltamethrin, etofenprox, fenvalerate, permethrin, prallethrin, profulthrin, resmethrin, silafluofen, sumithrin, tetramethrin, tralomethrin, transfluthrin, imiprothrin), and other compounds such as acetamiprid, alkybenzyldimethyklammonium chloride (BAC) and other quaternary ammonium compounds, azaconazole, borates (such as borax or disodium octaborate) or boric acid, chlorfenapyr, chlorothalonil, chlorpyrifos, clothianidin, copper naphthenate and other copper soaps, copper oxine, cyproconazole, didecyldimethylammonium carbonate/bicarbonate, didecyldimethylammonium chloride, fipronil, flonicamid, imidachloprid, indoxacarb, iodopropynylbuthylcarbamate (IPBC), isothiazolones (such as benzisothiazolinone (BIT), butylbenzisothiazolinone (BBIT), chloromethylisothiazolinone (CMIT), dichlorooctylisothiazolinone (DCOIT), methylisothiazolinone (MIT), octylisothiazolinone (OIT)), nitenpyram, propiconazole, pyrethrins, tebuconazole, thiabendazole, thiachloprid, thiamethoxam zinc naphthenate, other zinc soaps and mixtures thereof.
10. 10. A method according to any one of the preceding claims, wherein said treated wood is classifiable in the art as “dry after” (moisture content <15% w/w) following treatment with said preservative.
11. 11. A method according to any one of the preceding claims, wherein, by result, the quality of treated wood is approximately equivalent to that treated by prior art means (e.g., approximate 10 minute immersion, loosened or removed ties/straps).
12. 12. A method according to any one of the preceding claims, wherein said preservative comprises a wetting agent, a rheology modifier and/or a colour additive.
13. 13. A method according to claim 12, wherein the colour additive is blue.
14. 14. An apparatus when used for treating timber in accordance with the Australian H2F Standard, AS 1604.1-2012, said apparatus comprising: a treatment vessel; immersion means by which said timber may be operatively associated with said treatment vessel over a period of from around 2 minutes to around 10 minutes; rotation means for rotating said timber about two or more axes, thereby to actively expel air bubbles from said timber and to facilitate the movement of said preservative about said timber, thereby to relatively optimise the surface area of timber available to said treatment solution; and means for removing said timber from said treatment vessel.
15. 15. An apparatus according to claim 14, wherein said treatment vessel comprises, in use, an effective volume of a timber preservative treatment solution, said immersion means thereby operative to immerse said timber at least partly below the surface level of said treatment solution.
16. 16. An apparatus according to claim 14 or claim 15, wherein said immersion means is an automated hydraulic system associated with an automatic control unit.
17. 17. An apparatus according to any one of claims 14 to 16, wherein said immersion means is integral with said rotation means.
18. 18. An apparatus according to any one of claims 14 to 17, wherein said treatment vessel has a volume of up to about 100 m .
19. 19. In a timber dip treatment process, an improvement comprising rotation of immersed timber, over a total immersion time of from around 2 minutes to around 10 minutes, about two or more axes, thereby to actively expel air bubbles from said immersed timber and to facilitate the movement of said preservative about said timber, thereby to relatively optimise the surface area of timber available to the treatment solution, and thereby to relatively optimise the quality and/or coverage of the so-treated timber, wherein said timber is treated in accordance with the Australian H2F Standard, AS 1604.1-2012.
20. 20. Treated timber, when so-treated by a method according to any one of claims 1 to 13.