WO2005083198A1

WO2005083198A1 - Formply alternative

Info

Publication number: WO2005083198A1
Application number: PCT/AU2005/000265
Authority: WO
Inventors: David Murray James
Original assignee: Orica Australia Pty. Ltd.
Priority date: 2004-02-27
Filing date: 2005-02-25
Publication date: 2005-09-09

Abstract

Use of powder coated wood as a form guide for flowable, hardenable substances to provide a desired finish to an off-form surface of the substance, wherein the powder coat comprises thermoset polymer.

Description

FORMPLY ALTERNATIVE

Field of the Invention

This invention relates to the field of concrete construction and building product for use as an alternative to formply for concrete formwork.

Background of the Invention

Formply is a layered timber product which is used in construction to produce smooth concrete finishes. Formply is arranged to provide suitable formwork into which concrete is poured. Formply is a laminated wood product, namely plywood, having a thin veneer of hardwood timber on the face intended to contact and restrain the concrete. It is used to produce a satisfactory off-form finish quality in the set concrete.

In Australia the major formply producers produce 17 mm thick formply having a 2 mm imported rainforest timber veneer. The plywood is sourced from sustainable plantation or regrowth sources and the product is subject to a certification program. The veneer is largely imported, although locally grown hardwoods have been used as an alternative but are less well accepted because they do not provide as good a quality finish in the off-form concrete.

There has been a marked growth in the use of formply in Australia. Both a building boom and an increased demand by architects for surfaces requiring rainforest formply are thought to be contributing factors. Furthermore, it is often discarded after a single use. To meet the demand Australia, like other countries, have been importing large qualities of formply from South-East Asia.

According to a 9 April 2003 Hansard report of the New South Wales Legislative Council, imported formply is not manufactured under a program which ensures product reliability and safety. The use of imported formply from the forests of South-East Asia was reported to result in lower quality concreting and is seen as a threat to the public and worker safety. Furthermore, it is largely produced from forests which are not sustainably harvested. There has been a long felt need for an alternative to traditional formply. The apparent success of Indonesia's "Get tough" policy on illegal logging and possible ban on future hardwood exports had made the need for a viable alternative all the more urgent.

GB 2,155,850 and 2,220,153 (Kobunski Giken Kabushiki Kaisha) describe an apparatus for the production of filmed form work. The apparatus provides a process in which a board travels via a conveyor under a dispenser whereby adhesive resin powder is applied to the board, the powder is then heated on the board and hot roll pressed in order to make the resin spread over the surface of the board. A second dispenser is subsequently used to disperse a non-adhesive resin powder on the first film which is then heated and then subsequently cooled. In both patents an adhesive polyolefm copolymer resin is first applied to a plywood board and subsequently a non-adhesive polyolefm resin powder is applied to a film formed from the first resin. The described processes do not use thermoplastic polymers and require the use of an adhesive polymer binding material.

WO 02/094453 (DSM N.N.) describes a method for powder coating substrates in general when the substrate is porous by preheating the substrate to at least 5° above the melting temperature of the powder coating composition applying the powder coating composition to the preheat substrate and curing the powder coating composition. The method is described with reference to oak and walnut wood although, it is suggested for use on a wide range of substrates including metal and ceramics.

Brief Description of the Invention

The invention is predicated on the discovery that powder coated plywood ("PCP") can provide an acceptable alternative to traditional formply. The powder coat layer provides the requisite smooth surface finish in the off-form concrete. It can also provide a durable, peel resistant water-proof layer which should reduce warping of the substrate plywood and may permit the re-use of the PCP. This can be achieved by the use of a thermoset powder coating composition on the substrate.

Broadly stated, the invention relates to the use of powder coated wood as an alternative to formply. More particularly, it is used as a form guide with flowable, hardenable substances such as concrete or cement, which provides a desired off-form finish (typically a smooth finish).

In an embodiment of the invention there is provided the use of powder coated wood as a form guide for flowable, hardenable substances to provide a desired finish to an off-form surface of the substance, wherein the powder coat comprises thermoset polymer.

In another embodiment of the invention there is provided the use of powder coated wood as a concrete form guide to provide a desired finish to an off-form concrete surface, wherein the powder coat comprises thermoset polymer.

In another embodiment of the invention there is provided the use of powder coated plywood as a concrete form guide to provide a desired finish to an off-form surface of the concrete, wherein the powder coat comprises thermoset polymer.

In another embodiment of the invention there is provided an improvement in formply, wherein the rainforest or hardwood veneer of formply is replaced with a powder-coated layer of thermoset polymer.

In another embodiment of the invention there is provided powder-coated wood, preferably plywood, when used as a concrete form guide that provides a finish, typically a smooth finish, to an off-form surface of the concrete, wherein the powder-coat comprises thermoset polymer. In another embodiment of the invention there is provided a formguide for providing a desired finish to concrete, wherein the formguide is powder-coated wood, preferably plywood, wherein the powder coat comprises thermoset polymer.

In another embodiment of the invention there is provided a method of providing a desired off-form finish to a flowable, hardenable substance, by providing wood having at least a face powder coated with a thermoset polymer, the shape of the powder coated face being complementary to the desired off-form finish; including the wood in formwork for use in defining the form of the hardened substance, with the polymer coated face positioned to contact and restrain the substance within the formwork; adding the substance into the formwork; and allowing the substance to harden in the forπrwork and contact with the polymer coated face of the wood.

Detailed description of the Invention

As mentioned earlier the invention pertains to the use of powder coating technology to wood products, preferably plywood, to provide an alternative to formply.

The wood used as a substrate for the powder coating may be selected from a wide range of materials. Whilst natural timbers could be used, it is preferred to use a manufactured or engineered wood product, as such products can consistently meet the same quality standards.

A large number of different types of engineered wood products exist and may be utilised in the present invention. Reconstituted wood substrate (RWS) is substrate produced from wood particles, fibres, flakes or chips such as hardboard, medium density fibreboard (MDF), wafer board, flake board, chip board and particle board. RWS is produced by combining the particles, fibres, flakes or chips with a binder and compressing into a sheet. Plywood is another engineered product and is a laminate formed from joining relatively thin layers of veneer together, with the grain of adjacent layers at right angles. Plywood may have a core of RWS. Whilst various types of woods could be used as formwork for concrete, in practice plywood is normally used, for reasons of its strength (resistance to warp under load) and cost, and thus is the preferred wood for use with the invention.

The shape of the face of the substrate intended to contact and restrain the concrete will affect the off-form finish of the concrete. Typically, a smooth and flat finish is required in the concrete and thus the corresponding face of the wood. The use of a thin flat veneer of hard wood or rain forest timber has limited the concrete to flat finishes. However, it is envisaged that more complicated finishes may be provided by using a powder coat layer since the application of a powder coating is not limited to use on a straight and flat surfaces. A powder coat layer may provide a smooth finish on a curved or otherwise shaped wooden surface. The shape of powder coated contact face will be a complementary shape to the shape of the off-form concrete.

At least the face of the wood substrate intended to contact to concrete (the contact face) should be powder coated. This face is preferably an elongate face and preferably is substantially flat and smooth. When the substrate is plywood panels then it is expected that the manufacturing process will provide a suitably flat and smooth surface for coating. However, when the substrate is low grade timber then the surfaces may be 'rough cut' and may require sanding or a substantially thicker powder coat layer in order to cover the more significant surface imperfections.

Other faces of the wood substrate may also be coated. Preferably, the longitudinal edges would be coated and more preferably all edge faces would be coated. The face opposite to the contact face (the rear or opposed face) may also be coated. It is thought that coating the edge faces will improve overall water resistance and thereby prevent environmental water from warping and weakening the substrate thereby extending its useable life. It is envisaged that the coated substrate should be useable as a concrete form guide a number of times. The opposed face may also be coated. However, it is thought that the water exposure of this face is less than the other faces and as such may not need to be coated with the attendant cost savings.

Alternatively, the edge faces may be separately coated with a sealant. This may be done after the coated wood substrate has been cut to a desired size.

The typical dimensions should correspond with that of formply. The length may be from 100 mm to 3.5 m. The width may be from 30 mm to 2 m. The thickness may be from 2 mm to 50 mm. The thickness and overall strength of the substrate should comply with any local standards or requirements for formply as it should function as formwork for concrete (or other flowable, hardenable substances). Ordinarily in Australia the substrate would be plywood panels and typically of a length of 1.5 m to 2.5 m, width 1.5 m and 15 mm thickness. The coated panels could then be cut into strips for use as an alternative to formply.

The powder coating process involves applying a polymer powder to the substrate, typically by electrostatic coating techniques, and then fusing and temperature and / or UV curing the powder. The particles melt, flow and fuse together and transform into a smooth, typically high gloss, coating. The curing step causes the polymers to cross-link (chemically bond together) to provide a polymer network with toughness and water resistance whilst still retaining a suitable degree of flexibility. The powder coating process also provides an environmentally friendly method of applying a coating as a solvent is not required and the overspray particles that are not bonded to a substrate can be collected and re-used in the next powder coating application.

There are a number of problems with powder coating wood. The electrostatic coating techniques act by charging the particles and require the substrate to be coated to hold an opposite charge. Whilst this works well with metals, it is more difficult to form and hold the required charge on wood or plastic substrates. When powder coating plywood for use as an alternative to formply, it can be helpful to improve charge retention by heating the wood substrate to a temperature over 80°C. This increases the amount of water at or near the surface of the wood and permits a charge to be more easily held. Other techniques that may be used include applying a brief burst of water to the wood or applying a conductive coating to the wood. The latter approach has some disadvantages, not the least being requiring an additional step and the waste, solvents and drying time associated therewith.

Another difficulty with powder coating wood products with thermosettirig polymers is the need to fuse and cure the powder coat composition. Unlike thermoplastic compositions, a thermosetting composition must be cured in order to obtain a desired degree of cross- linking.

A thermoset resin is used with a cross-linker or cure agent, and the cross-linking may be initiated by a number of different methods, for example, by UN light or by heat. In general, a thermoset powder which has been cured and cross-linked will not melt and flow again if subject to the same fusing temperature. Unfortunately, traditional thermosetting powder coating compositions fuse and cure at temperatures over 180°C and such temperatures are unacceptable for woods, particular manufactured woods, as it can damage the strength of the end product and warp the substrate.

Low temperature fusing and curing powder coating compositions have been developed but the use of those compositions can cause problems. The powder is normally prepared by heating together granules of desired polymers, curing agents and additives and extruding the mixture to provide a homogeneous mixture, which is cooled on cooling rollers before the extrudate is ground and screened to provide the desired particle size. Heat is applied to the barrel in order to facilitate the flow of the extrudate at an adequate rate in a production environment. The extrusion of the mixture also generates heat. In production the powder can be subject to temperatures over 95°C, typically 110°C and can be over 120°C and this can lead to powder gelling in the extruder. Preferably for ease of use and handling, the powder coating composition should flow at a temperature at least 5°C to 10°C, and more preferably at least 10°C below the curing temperature. Various powder systems have been proposed and developed to try to overcome these problems. UV in combination with thermal curing systems can be used to cure the low temperature coating compositions.

Another problem with powder coating wood is the presence of volatile chemicals. Natural and manufactured woods contain water, oils and, in the case of manufactured woods, binders, solvent residues and other chemicals. Whilst these chemicals may not be a cause of concern at room temperature, when the wood is heated during the fusing and / or curing process volatile chemicals will leave the wood product, passing through the curing powder coating layer and can cause pinholes and blisters. Even after curing the residual presence of volatile chemicals in the wood can cause problems with the gas expansion of the chemicals flexing the wood and cracking the powder coat layer.

A number of documents describe thermosetting powder coating compositions and methods of coating wooden substrates that may be useful to provide powder coated wooden substrates and, more preferably, PCP suitable for use as an alternative to formply. Two useful non-patent references are Volume 1 of Powder Coatings: The Technology, Formulation and Application of Powder Coatings by David M Howell, John Wiley & Sons Ltd, London, 2000 and The Technology of Powder Coatings by S.T.Harris, Portcullis Press Ltd, Surrey UK, 1976.

The following patent documents describe general and specific powder-coating methods and the compositions used therein, and their polymers, initiators, curing agents, additives and other components for use in powder coating wood substrates. The information in the brackets provides an indication as to the relevance of the patent. The methods for powder coating wood and compositions, additives therein may also be useful in the manufacture of PCP for use as an alternative to formply. US 4,000,333 (primer composition); US 4,360,385 (pre-coating compositions for improving electrostatic properties); US 4,53 0,778 (conductive pretreatment solution); US 5,344,672 (preheating the substrate to degasify it before applying powder coat); US 5,703,198 (UV curable powder coat composition); US 5,714,206 (overcomes extruder gelling by addition of a separate powder coring agent after extrusion before electrostatic delivery and provides pleasing smoothness); US 5,922,473 (powder coat compositions); US 5,925,698 (use of slip enhancing additive to protect against damage); US 6,005,017 (thermal and UV cure composition with enhanced surface smoothness); US 6,011,080 (inclusion of recrystallisation inhibitor to prevent hazing); US 6,017,640 (dual cure powder coat system); US 6,022,927 & US 6,025,030 (weatherable powder coat compositions); US 6,048,949 (polyester powder coatings); US 6,077,610 (two component self-curing epoxy powder coat composition having separate curing agent to avoid gelling in extruder); US 6,136,370 (outgassing of volatiles via non-coated surface); US 6,146,710 (modification of substrate to improve charge retention); US 6,153,267 (application of mist of^" water to substrate to enliance electrostatic properties); US 6,238,750 (spraying powder onto substrate followed by membrane pressing ; US 6,268,022 (two step powder coating delivery to substrate); US 6,294,610 (low teimperature curing composition); US 6,319,562 (use of heat to fuse powder followed by ITV curing); US 6,296, 939 (heating substrate); US6,433,099 (low temperature powder coating composition); US 6,436,485 (use of halogen bulbs to IR-cure powder coat); US 6,458,250 (treatment of substrate to steam and heat to enhance electrostatic properties); US 6,509,413 (low temperature epoxy system); US 6,537,671 (use of inert nitrogen containing compounds in composition to enhance electrostatic charge); US 6,548,109 (pre-treatment with low viscosity wetting material to enhance bonding); US 6,592,665 (plant apparatus for powder coating); US6,620,463 (pre coating with conductive primer); US 2002/0176941 (differential treatment of sides of substrate); US 2003/0026897 (automatic machine for preheating substrate, applying powder, fusing powder), US 2003/0087029 (use of spheroidal particles to reduce gloss and improve smoothness); US 2003/0143325 (cooling substrate); US 2003/0158285 (lists assorted additives for use in compositions)- US 2003/0199640 (radiation curable powder coat composition); US 2003/0211252 (horizontal conveyer and powder coating system); WO92/01517 (repetitive heating cycles to avoid damage to substrate); GB 2,024,658 (precoat with polyester resin before powder coat layer to improve crack resistance); GB 2,056,885 (general description of powder coating of wood substrates and formulations); EP 806,458 (triboelectric coating formulations for use on wood); EP 933,140 (preheating substrate) and EP 1,252,938 (differential treatment of substrate surfaces).

As described in a number of the above documents the wooden substrate may be prepared, by for example, applying the powder coating by an electrostatic spray technique (such as with a triboelectric or corona gun). Other techniques such as fluidised bed techniques may also be employed. The powder can be applied by allowing it to fall onto the substrate, by using for example a vibratory hopper. This is useful for coating a single side of a substrate.

Vertical (hanging substrate) or horizontal coating systems could be used in the coating process. Each system has advantages. Horizontal powder coating systems, such as that described in US 2003/0211252, may be of particular use with longer lengths of substrate than could be reasonably attached to a hanging conveying system and should permit the powder coating of the main contact face and edge faces. Hanging systems allow the substrate to be entirely coated in a single pass with multiple electrostatic guns that apply the powder to all sides. Alternatively, electrostatic guns could be used to spray the powder on at least one face of a suspended substrate and the charge on the substrate may also result in some coverage of the edge faces and lesser coverage of the opposed face. Horizontal systems can still be used to provide a wholly coated substrate that could be coated in sequential powder coating steps.

A wide range of polymers are described in the earlier mentioned patent literature and may be used in the present invention. Typically, the powder will be based on polyester including polyester TGIC (epoxy functional cross-linker triglycidyl isocyanurate), epoxy, hybrid blends of polyester / epoxy, polyurethane, acrylics including acrylic hybrids, urethane acrylics and glycidyl acrylate acrylics (GMA) and other suitable cross-linkable resins. Preferably, it will be UV curable. Also favoured are dual cure polymer coatings such as those listed in US 5,922,473. The resin may contain colour pigments, extender pigments, cross-linkers and other additives. Examples of pigments and fillers include metal oxides, such as titanium oxide, iron oxide, zinc oxide and the like, metal hydroxides, metal powders, sulphides, sulphates, carbonates, silicates such as aluminium silicate, carbon black, talc, kaolines, barytes, iron blues, lead blues, organic reds, organic maroons and the like.

A slip-enhancing additive may be included to improve coating wear characteristics such as that described in US 5,925,698.

Powder coating compositions may contain other coating modifiers such as polytetrafluoroethylene modified waxes, polyethylene waxes, polypropylene waxes, polyamide waxes, organosilicones and blends of the above.

Photo-initiators suitable for inclusion in UV powders include aromatic carbonyl compounds, such as benzophenone and alkylated or halogenated derivatives, anthraquinone and its derivatives, thioxanthone and its derivatives, benzoin ethers, aromatic or non-aromatic alphadiones, benzol dialkyl acetals, acetophenone derivatives and phosphine oxides.

Preferably the powder will be prepared by pre-mixing the polymer components and extruding the hot mixture to form an extrudate, which is then granulated and ground into powder.

A curing agent is usually added to the composition before extruding the mixture.

The particle size can range from 2 to 200 micrometers and more preferably 1O to 100 micrometers. The preferred medium size is 50 micrometers.

The coating powder is typically applied to achieve a thickness of 0.04 to 0.6 mm, more preferably less than 0.1 mm. The powder is typically applied in a thickness from 0.08 to 0.13 mm. The substrate can be passed through twice or more times to further increase the thickness of the layer.

When the substrate is provided with multiple layers of the powder coating, each layer may be the same or different. For example a primer and top coat system could be used. The primer layer may be a sandable primer for use with substrates with a rough contact face. The primer powder coating formulation may include a texture additive such as Bentone or Dyncon TF1641 in order to improve the sandable properties of the primer layer.

Preferably the composition is applied electrostatically using triboelectric or corona charged means.

After the powder coating has been applied, the coating is first fused by heating the powder and substrate. Localised heating using IR lamps is preferred to limit the exposure of the substrate to heat. The powder may then be cured by thermal or UV or by the combination. Hg containing lamps have been found to be effective for UV curing.

Examples

Unless otherwise indicated the mixtures were prepared by combining the ingredients (resins, initiators, colour pigments, extenders, flow additives and other minor additives). The mixture was then agitated and then heated and extruded at 100°C to provide a homogenous sheet. The sheet was cooled, granulated and then milled and sieved to provide particles having a particle size less than 90 micrometers (average particle size of 50 microns) to provide the powder coating composition. All amounts are parts by weight.

The powder coating compositions was applied electrostatically to the substrate material and cured. UV curing used Hg and Hg/Ga UV lamps. Heat curing involved the use of an IR oven. Table 1. - UN Single Coat Formulations

Coating formulation 1 was applied to and cured on normal MDF for 5 minutes at 70°C, then by IR for 2 minutes at 200°C and with 3 passes of UV. The coated MDF panel was examined and found to provide a hard (no marring) and smooth surface without voids or dimple effects. The coated surface of the panel was water tested with steam for 3 minutes and examined. No water damage was noted.

Coating formulation 2 was applied to plywood that had been preheated for 5 minutes at 70°C, IR treated for 3 minutes at 200°C and subjected to 3 UN passes.

Coating formulation 3 was applied to jilywood preheated for 5 minutes at 70°C. The composition was IR heated for 1 minute at 200°C and by two passes through UV .

Coating formulation 4 was applied to a test panel and heated for two minutes at 200°C in an IR oven and by 3 passes through UV. The coating layer was then sanded to a smooth finish using "Norton" sanding paper for paint 400 grit with sanding block. A top coat of formulation 1 was then applied and cure d for 2 minutes at 200°C in an IR oven and with 3 passes through UV.

Coating formulations 5 and 6 were applied to plywood pre heated for 5 minutes at 70°C, and heated by IR for 2 minutes at 200°C and subjected to 3 passes of UV. The coated panels were examined and found to provide a hard (no marring) and smooth surface without voids or dimple effects. The coated surface of the panels were water tested with steam for 3 minutes and examined. No water damage was noted.

Coating formulations 7 and 8 were applied to plywood preheated for 5 minutes at 70°C. Formulation 7 was heated for one minxite at 200°C. Formulation 8 was heated for two minutes at 200°C. Both were subjected to 2 passes of UV. The coated plywood was found to provide a satisfactory surface with, a smooth finish capable of being used to as alternative to that provided by formply. Table 2. - UV Two Layer Primer Coatings

The formulations were used as a primer coat for plywood. The plywood was preheated for 5 minutes at 70°C, before the powder formulation was applied. The coatings were heated for 1 minute at 200°C and subjected to two passed of UV. The primer coatings were lightly sanded in preparation for a second coat.

All formulations were considered to be good UV Primer formulations for use in the manufacture of a coated product for use instead of formply. Table 3. - Low Temperature Primer Formulations

Coating formulations 15 and 16 were cured for 25 minutes at 150°C. The textured coatings were then sanded back to smooth finish using "Norton" sanding paper for paint 400 grit.

The coated substrates were examined and found to provide satisfactory results. In particularly, coating formulation 15 was considered to provide a coating that was textured enough to fill uneven substrate, had good surface adhesion and could be sanded. Coating formulations 17 to 19 were applied to a sanded preheated plywood test panel (8 minutes at 90°C) plywood test panel and cured for 20 minutes at 150°C. The coating layer was then sanded to a smooth finish suitable for formply alternative. The coatings 17 to 19 were considered to be satisfactory for use as a primer coat.

The coating formulations 20 to 22 were applied to preheated plywood test panels (8 minutes at 90°C) and heated for 20 minutes at 150°C. The coating was then sanded to a smooth finish and top coated with coating formulation 23 and heated at 20 minutes at 150°C. The test panels were all examined under the microscope and found to have a coated surface that was sufficiently smooth for use as an alternative to formply.

Coating formulation 22 was applied to a pre- sand preheated plywood test panel (8 minutes at 90°C) plywood test panel and cured for 20 minutes at 150°C. The primer layer was then sanded to a smooth finish, top coating formulation 23 was applied and cured at 20 minutes at 150°C. The surface finish was considered sufficiently smooth so that the panel could be used as an alternative to formply.

Coating formulations 24 and 25 provided suitable alternatives to formulation 23. They were applied to primed test panels which had been preheated for 5 minutes at 70°C, before curing for 20 minutes at 150°C.

Table 5 - Single Coat Low Temperature Formulations

Coating formulations 26 and 27 were applied to preheated plywood test panels (5 minutes at 70°C). The coatings were baked for 25 minutes at 150°C. The coating had good flow coverage and filled in the gaps in the plywood substrate. Both compositions produced a satisfactory finish so that the coated plywood could be used as an alternative to formply. Coating formulation 28 was applied to medium density fibreboard and cured for 20 minutes at 150°C. The coating hardened over time and provided a glossy smooth surface. Microscopic examination did not find any voids. Water resistance was tested by application of steam for 3 minutes followed by examination of the coating and substrate. No water damage was noted.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form or suggestion that that prior art forms part of the common general knowledge in Australia.

It would be appreciated by a person skilled in the art that variations and/or modifications may be made to the invention as described without departing from the spirit or scope of the invention as broadly described. The described embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. For example, whilst the invention is largely described by reference to plywood and PCP, it will be understood other wood substrates could be used in place of plywood and are encompassed by the invention.

Claims

CLAIMS:

1. Use of powder coated wood as a form guide for flowable, hardenable substances to provide a desired finish to an off-form surface of the substance, wherein the powder coat comprises thermoset polymer.

2. A method of providing a desired off-form finish to a flowable, hardenable substance, by providing wood having at least a face powder coated with a thermoset polymer; the shape of the powder coated face being complementary to the desired off-form finish; including the wood in formwork for use in defining the form of the hardened substance, with the polymer coated face positioned to contact and restrain the substance within the formwork; adding the substance into the formwork; and allowing the substance to harden in the formwork and contact with the polymer coated face of the wood.

3. The use or method as defined in claim 1 and 2, wherein the wood is an engineered wood.

4. The use or method as defined in any one of claims 1 to 3, wherein the wood is plywood.

5. The use or method as defined in any one of claims 1 to 4, wherein the flowable, hardenable substance is concrete.

6. The use or method as defined in any one of claims 1 to 5, to provide a smooth finish to an off-form surface of the substance.

7. The use or method as defined in claim 6, to provide a smooth and flat finish to the off-form surface of the substance.

8. The use or method as defined in any one of claims 1 to 7, as a replacement form guide for formply.

9. The use or method as defined in any one of claims 1 to 8, wherein two or more faces of the wood are powder coated with a thermoset polymer.

10. The use or method as defined in any one of claims 1 to 9, wherein the powder coated wood is used more than once as a form guide for flowable, hardenable substances.

11. The use of plywood powder coated with a thermoset polymer as a concrete form guide to provide a smooth finish to an off-form surface of the concrete.

12. Powder-coated wood when used as a concrete form guide to provide a desired finish to an off-form surface of the concrete, wherein the powder coating comprises thermoset polymer.

13 A formguide for providing a desired finish to an off-form surface of concrete, wherein the formguide comprises wood powder coated on a least one face with thermoset polymer.

14. An improvement in formply, wherein the rainforest or hardwood veneer of formply is replaced with a powder- coated layer of thermoset polymer.

15. A powder coating formulation for powdering coat wood for use as a form guide for flowable, hardenable substances substantially as hereinbefore described with reference to the tables 1 to 5.