METHOD FOR SURFACE TREATING ENGINEERED COMPOSITE BOARD

Abstract: A method for surface treating engineered composite board such as medium density fibre board to achieve a grain-like effect is disclosed. The method comprises the steps of: distributing a first surface treatment on the material in an irregular manner and in a predetermined direction to produce simulated grain colourings (20); applying a second surface treatment to the material in a substantially uniform manner (30); applying a sealant to the material (40); sanding the material (50); applying a third surface treatment to the material (60); applying a fourth surface treatment to any crevices of the material (70); and applying a finishing surface treatment to the material in a substantially uniform manner (90).

Description: TITLE "Method for Surface Treating Engineered Composite Board" FIELD OF THE INVENTION The invention relates to a method for surface treating engineered composite board to produce a grain effect similar to that found in wood. The invention has particular, although not exclusive, utility in relation to producing architraves and skirting boards that have the appearance of wood from engineered composite board. BACKGROUND ART Traditionally, forest wood is used to make skirting boards and architraves. These items were originally manufactured from hard woods such as Jarrah. Recently, the increasing cost of forest woods such as Jarrah and the environmental push to preserve forests have made this practice uneconomical. Further, even where forest wood is available, difficulties arise in producing long, straight lengths of timber for purposes such as architraves and skirting boards. Engineered composite board, also referred to as engineered wood panelled product, is a man made product. Examples of engineered composite boards include particle board and medium density fibre board (MDF). Engineered composite boards have achieved only partial success in acting as a forest wood substitute for architraves and skirting boards. This is primarily because the engineered composite board, even when stained, does not produce a realistic imitation of wood. Although the engineered composite board can be stained to achieve a similar colour to wood, the engineered composite board is a uniform colour and does not imitate the grain of the wood. Accordingly, it would be advantageous if a method of producing grain-like effects on engineered composite board existed. Numerous methods have been developed for treating wood to alter its appearance. Examples include the methods disclosed in USA Patent 5, 512, 323, USA Patent 1 , 548, 528, USA Patent 3, 069, 290 and USA Patent 3, 877, 958. The methods disclosed in these Patents rely on the existence of grain in the wood in order to achieve the desired appearance. In most cases, the processes are designed to highlight the existing grain in the wood. This is achieved by applying a first colour to the wood to fill the pores or grain of the wood. A second colour is then applied in such away as to colour the upper surface of the wood without covering the first colour in the pores or grain areas. This process takes advantage of the fact that grain in wood is recessed from the surface of the wood. Thus, one colour is applied to the grain and the other colour is applied to the remainder of the surface of the wood. Whilst these processes are effective on wood, they are not effective on engineered composite boards because the boards have a uniformed surface texture and do not have an existing grain. UK Patent 591 , 213 discloses a method for producing a grain-like effect on a surface which uses a pre-formed rubber stamp with a grain-like pattern etched thereon to stamp a simulated grain onto a surface. The use of a fixed stamp leads to repetitious appearance of the grain which yields unrealistic results. Further, the use of a stamp creates difficulties when working with moulded products such as architraves and skirting boards. Consequently, to date there has been no satisfactory method for producing a grain like appearance on engineered composite board. DISCLOSURE OF THE INVENTION In accordance with a first aspect of this invention, there is provided a method for surface treating engineered composite board, comprising the steps of: distributing a first surface treatment on the material in an irregular manner and in a predetermined direction; applying a second surface treatment to the material in a substantially uniform manner; and applying a finishing surface treatment to the material in a substantially uniform manner. Preferably, said method further comprises the step of sanding the material prior to the distribution of the first surface treatment. Preferably, said method further comprises the steps of: after applying the second surface treatment, applying a sealant to the material; sanding the material; applying a third surface treatment to the material; and applying a fourth surface treatment to any crevices of the material. Preferably, said method further comprises the step of applying a fifth surface treatment to the material after application of the fourth surface treatment. Preferably, the first surface treatment comprises stain and/or colouring. Preferably, the first surface treatment comprises a pigment colour. Preferably, the second surface treatment comprises stain and/or colouring. Preferably, the finishing surface treatment comprises one of a lacquer, acrylic or eurathane/polyurethane. BRIEF DESCRIPTION OF THE DRAWINGS This invention will now be described with reference to one embodiment thereof and the accompanying drawing, Figure 1 , which is a flow chart of the method for surface treating engineered composite board in accordance with the preferred embodiment of the invention. BEST MODE(S) FOR CARRYING OUT THE INVENTION The embodiment is directed towards a method for surface treating medium density fibre board (MDF) to produce skirting boards and architraves. It should be appreciated that other forms of engineered composite board can be used as desired. It should also be appreciated that the method can be applied to products other than architraves and skirting boards. The embodiment will be described with reference to making the MDF look like Jarrah. It should be appreciated that by appropriate choice of pigments and stains, the invention can be used to simulate almost any wood. Figure 1 is a flow chart of the method of surface treating engineered composite board according to the preferred embodiment. The method comprises the following steps: • Sanding 10; • Distributing a pigment colour on the engineered composite board in an irregular manner and in a predetermined direction 20; • Applying a pre colour treatment to the engineered composite board 30; • Applying a sealant 40; • Sanding the engineered composite board 50; - o - • Applying a first finish coat 60; • Applying a colour to crevices in the engineered composite board 70; • Applying a further colour to the engineered composite board 80; and • Applying a finishing coat 90. Each of these steps will be described in more detail below. SANDING 10 The production process of many engineered composite boards results in the outer surfaces of the board being treated to provided a sealed surface that has a low degree of water absorbance. However, once the engineered composite board is moulded, the sealed surface is removed to reveal a soft interior. This is particularly the case with medium density fibre board (MDF), which once machined reveals a soft interior made up of many fibres. These fibres are disturbed by the moulding process, resulting in fibres standing in many different directions. This makes it difficult to produce a smooth surface on the MDF. Further, once water or solvent based products are applied to the MDF, these fibres can harden which again produces a rough appearance. These problems have lead to MDF in particular being considered not suitable for some applications. To reduce the effect of the fibres, the MDF is sanded prior to any surface treatment being applied. One of the difficulties with conventional sanding is that it can further disturb the fibres and therefore not provide any advantage. However, it is been found that by replacing conventional wood sanding discs with polishing discs ordinarily used to buff metal, a fine sanding and buffing is achieved. Further, it as advantageous if the discs are cut to the same profile as the MDF moulding, since this assists the dust and fibres sanded from the surface to fill any gaps in the surface and produce a smoother surface. DISTRIBUTING PIGMENT COLOUR IN AN IRREGULAR MANNER AND A PREDETERMINED DIRECTION 20. Next, a first surface treatment in the form of pigment colour is applied to the MDF in an irregular manner and distributed in a predetermined direction. This achieves a grain-like effect. Pigment colour is preferred since it does not fade. It is also preferred that the pigment colour is darker than the remaining colours applied in subsequent steps to emulate the generally darker grain colours in wood. By applying the pigment to the MDF prior to applying a sealer, the pigment colour soaks in to the MDF better. The pigment colour can be applied in a number of different ways. However, it is important that the effect is relatively random and appears to be straight in a single direction similar to the grain of wood. It has been found that by applying the pigment stain with a brush which has a small amount of pigment stain on it and which is lightly passed over the surface of the MDF, good results are achieved. However, other processes can be used, so as long as they produce the desired grain-like appearance. APPLY PRE COLOUR 30 A second surface treatment in the form a pre colour is then applied to the upper surface and edges of the MDF. The pre colour comprises a mix of pigment stain and thinners. The pre colour is applied using one or more spray guns provided at an angle so that spray covers both the edge and the upper surface of the MDF. APPLY A SEALER 40 Next, a sealer is applied to the MDF. The sealer acts as a primer on any remaining waxed surfaces of the MDF, which assist subsequent lacquer treatments to adhere to MDF. Further, the sealer makes the fibres of the MDF become erect and rigid. Although this is generally considered an inconvenience, in this instance it is considered desirable because it permits the fibres to be sanded off in a subsequent step and leave a smooth, uniform surface. The sealer also acts as a protective coat over the pigment colour distributed as grain so that the grain effect is not removed during the subsequent sanding step. SAND 50 The MDF is again sanded and buffed using the same polishing discs used in previous step 10. Because the fibres of the MDF have become ridged with the application of the sealer at step 40, the light sanding and buff allows these fibres to be removed to leave a smooth surface. APPLY FINISH COAT 60 Next, a third surface treatment in the form of a finish coat is applied to the MDF. In the embodiment, the finish coat is a mixture of two colours, Jarrah and Burnt Umber, combined with lacquer. APPLY LINES IN CREVICES 70 One of the difficulties in treating moulded products, particularly where the surface treatments are applied using a spray gun, is ensuring an even coat of surface treatment is applied in crevices of the material. In particular, moulding such as a traditional federation skirting board and architrave have narrow "V" shaped crevices, which are not adequately covered using conventional spray techniques. If the amount of colouring is increased to adequately cover the crevices, then the remaining areas of the MDF are flooded and over filled. To avoid this problem, the finished coat applied at step 60 is applied in a generally light coat to provide a uniform coat to the majority to the surface of the MDF. Then, a narrow beam spray is used to apply highlight lines, or shadowing, in any crevices of the moulding. This avoids light areas where the finished coat applied step 60 did not cover the crevices. Burnt Umber is used in this step to achieve a dark appearance. It has been found that this step can considerably improve the aesthetic appearance of the finished product whilst simultaneously avoiding shortcomings in current spray technology. - o - APPLY TOP COLOUR 80 A top colour, comprised of a mixture of stain and thinners is then applied using a spray gun. An even coat of the top colour is applied to achieve the final colouring. APPLY FINISH COAT 90 Finally, a finishing surface treatment in the form a mixture of lacquer and Jarrah and Burnt Umber colourings is applied to the MDF. The embodiment produces MDF products which provide a good copy of jarrah wood. In particular, producing a grain-like effect which is distributed in direction significantly enhances the realism of the product. Although the embodiment has been described with reference to MDF, it should be appreciated that other forms of engineered composite board can be used. Further, it should be appreciated that by adjusting the colours and pigment used, the MDF or other engineered composite board can be made to appear like other forms of wood, such as Tasmanian Oak, American Oak and Beech. For example, if it was desired to simulate a light coloured wood such as Tasmanian Oak, the pigment colour in step 30 is replaced with liming. If desired, the liming can also be applied in the crevices at step 30. A clear lacquer is used as the first finish coat applied in step 60. The top colour in step 80 uses a suitably light pigment colour and thinners, and the finish coat used at step 90 is a clear lacquer. It should be appreciated that the scope of this invention is not limited to the particular embodiment described above.

Claims: - y - CLAIMS 1. A method for surface treating engineered composite board, comprising the steps of: distributing a first surface treatment on the material in an irregular manner and in a predetermined direction; applying a second surface treatment to the material in a substantially uniform manner; and applying a finishing surface treatment to the material in a substantially uniform manner. 2. The method of claim 1 , further comprising the step of sanding the material prior to the distribution of the first surface treatment. 3. The method of claim 1 or 2, further comprising the steps of: after applying the second surface treatment, applying a sealant to the material; sanding the material; applying a third surface treatment to the material; and applying a fourth surface treatment to any crevices of the material. 4. The method of claim 3, further comprising the step of applying a fifth surface treatment to the material after application of the fourth surface treatment. 5. The method of any one of claims 1 to 4, wherein the first surface treatment comprises stain and/or colouring. 6. The method of any one of claims 1 to 4, wherein the first surface treatment comprises a pigment colour. 7. The method of any one of claims 1 to 6, wherein the second surface treatment comprises stain and/or colouring. 8. The method of any one of claims 1 to 7, wherein the finishing surface treatment comprises one of a lacquer, acrylic or eurathane/polyurethane.

Inventors: THOMSON PETER FRANCIS, THOMSON, PETER, FRANCIS
Applicants: THOMSON PETER FRANCIS, TUDOR LODGE PTY LTD, THOMSON, PETER, FRANCIS, TUDOR LODGE PTY. LTD.
Application year: 1999
Main classification: B27K5
IPC codes: B05D7