AU2009208100A1 - Decorative perforated facing for acoustic panels - Google Patents

Description

15282AU ORIGINAL Complete Specification Applicant: Neil Ridgeway Title: Decorative perforated facing for acoustic panels Address for Service: LESICAR PERRIN, 49 Wright Street, Adelaide, South Australia 5000, Australia The following statement is a full description of this invention, including the best method of performing it known to melus: Decorative perforated facing for acoustic panels FIELD OF THE INVENTION This invention relates to a method of making a decorative perforated facing for acoustic panels and tiles that form a manufactured surface placed about the interior of a 5 building in order to absorb or modify background noise levels and sound reflected from floors, walls or ceilings. DEFINITION Please note that the tenn "coloration" as used herein refers to a visible appearance 10 rather than an actual colour. For example the term may refer to different degrees of saturation or brightness of the same colour, or to different surface finishes in the same colour, or to finishes having different reflectivity, lustre or sheen, and also includes different colours. BACKGROUND 15 Acoustic panels are commonly used to form the ceiling of a building or line the interior walls and can be made from a variety of materials including wet felt mineral fibre board, laminated fibreglass, laminated rockwool, perforated wood, perforated gypsum and perforated metal. It is typically beneficial for such panels to have a decorative surface, good sound absorption properties, good structural strength such as stiffness and resiliency, 20 flame resistant, economical and be easy to work on site. Prior art type acoustic panels such as wet felt mineral fibre board are typically pin perforated and painted whilst dry felt mineral fibre and dry felt glass fibre boards are typically faced with a plain or painted glass tissue facing and are efficient absorbers of sound energy due to their porous baseboard composition. 25 Panels made from plywood, medium density fibre board, fibre cement, plasterboard, steel and aluminium sheet are hard and reflective to sound energy and must be perforated to allow sound to penetrate the surface into absorbent material at the rear of the panel. Such perforated panels often exhibit a pleasing decorative finish that is desirable 2 for interior decoration but are high cost to manufacture and install and often require additional painting and finishing on site. The usual way to make perforated acoustic panels is to start from a sheet of a hard non-absorbent material of the final thickness, then drill holes and cut edges (using 5 equipment such as a numerically controlled drill, laser, router or other cutter), apply finish coatings, and back each panel with absorbent material in order to make a series of tiles. That method is relatively expensive, and in the inventor's experience is liable to have inherent errors. The acoustic performance of such panels is dependent on the type of hard material, its thickness, the size and number of perforations and the type of absorbent 10 material applied to the back. The acoustic properties of tiles of this sort are inferior. It would be advantageous to provide a porous acoustically transparent, prefinished semi rigid decorative perforated facing panel that can be applied to sound-absorbing wet felt mineral fibre, dry felt mineral fibre, dry felt glass fibre boards as well as to hard panels wherein the decorative facing does not unjustly modify the acoustic performance of the 15 baseboard panel It would also be advantageous to provide a perforated facing panel that is economical to manufacture in a wide range of decorative designs, will self centre and align itself in a frame, is compact and light weight to reduce transport and storage costs, have a low embodied energy content, is fire resistant, easy to cut and trim with a hand knife and 20 can be manufactured locally without significant capital investment on a small scale close to the market place of use. The object of this invention may be stated as to provide an improved facing for acoustic surfacing applications, and a method of manufacture of same, or at least to provide the public with a useful choice. 25 STATEMENT OF INVENTION An acoustic facing material, wherein the acoustic facing material is comprised of more than one layer of a felted mat having an outward or exposed surface layer; each layer of the material being comprised of a material selected from a range including (a) felted glass fibre or other vitreous fibre, or (b) plastics fibre including without limitation polyester 3 fibre, or (c) a blend of both a vitreous and plastics fibre material, and the layers are mutually adherent over their adjacent surfaces. Preferred adhesives for this purpose include a "hot melt glue" resin or a water based PVA or PVU glue; preferably also having flame-retardant properties. 5 Preferably the acoustic facing material has an outward or exposed surface and an backing or supporting surface; wherein the outward surface layer has a first visible coloration and is configured by cutting out one or more apertures from the outward surface layer in order to partially expose a continuous underlying layer to which the outward layer is adherent; the underlying layer having a second visible coloration; thereby providing 10 decorative aspects without compromising the acoustic properties of the material. Optionally, an intermediate non-continuous layer having a third visible coloration is used to expose, through one or more apertures, portions of an underlying layer having the second coloration. In a first related aspect, the outward surface layer is comprised of a plurality of 15 outward relatively thin, adherent layers; each layer including one or more apertures; the layers being laid over each other with the apertures in register. Optionally the outermost surface is cut so as to have one or more apertures and a decorative appearance arises if an underlying layer, of a contrasting colour, is not so cut. Preferably, the outward surface layer has a thickness of between 1 and at least 20 8 mm. In one option, the material is provided as unit panels or tiles. In another option, the material is provided in a bulk form such as large sheets or in rolls. In a second related aspect, a series of tabs, nodes or protrusions are formed around 25 the perimeter of each unit panel or tile; said series being capable in use of serving as means 4 to locate the unit panel or tile within a supporting frame in order to align the decorative perforated design from panel to panel and to achieve a uniform tessellated design over a wall or ceiling. In a third related aspect the acoustic facing or tile includes in sequence from the 5 outward surface: an outward discontinuous surface layer having a first coloration, a continuous underlying layer having a second coloration to which the outward layer is adherent; the acoustic facing material or tile further including an optional backing of an acoustic tissue, an optional layer of a non permeable vinyl or other foil, and a backing board having an effective thickness and density; the backing board being selected from a 10 range including glass fibre board, dry felt glass fibre board, and plaster board. In a further broad aspect, the invention provides cutting means, such as a die, shaped in order to cut a tile from a sheet of a glass fibre mat; the shape of the die incorporating means for cutting the series of tabs, nodes or protrusions around the perimeter of the tile. 15 Preferably the cutting means further includes means for creating at least one aperture through the sheet. Optionally the facing panel may be supported on a backing board selected from a range including mineral fibre, rock wool, plaster board, glass fibre board, and other backing boards. 20 In a related aspect an acoustic facing or tile includes, from the exposed surface: a glass fibre mat optionally bearing a plurality of decorative apertures a glass fibre mat having at least one lamination, an optional backing of an acoustic tissue, an optional layer of a non permeable foil, and a backing board selected from a range including glass fibre board, dry felt "rock wool" fibre board, dry felt glass fibre board, wet felt mineral fibre 25 board, man-made mineral fibre board, or other vitreous fibre board, plaster board and other backing boards known in the art. Optionally the glass fibre mat assembly includes a backing layer of a non perforated impermeable vinyl or other foil in order to reflect high frequency sound and 5 absorb low frequency sound when adhered to a glass fibre board or other soft fibre board having an effective thickness and density. In a further broad aspect the invention provides a method for making acoustic tiles, wherein the shapes to be cut out are constructed within a cutter that punches the 5 shapes, including the shapes of decorative holes in the surface layer. PREFERRED EMBODIMENT The description of the invention to be provided herein is given purely by way of example and is not to be taken in any way as limiting the scope or extent of the invention. Throughout this specification unless the text requires otherwise, the word 10 "comprise" and variations such as "comprising" or "comprises" 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. Each document, reference, patent application or patent cited in this text is expressly incorporated herein in their entirety by reference, which means that it should be 15 read and considered by the reader as part of this text. That the document, reference, patent application or patent cited in this text is not repeated in this text is merely for reasons of conciseness. Reference to cited material or information cited in the text should not be understood as a concession that the material or information was part of the common 20 general knowledge or was known in New Zealand or any other country. DRAWINGS Fig 1: A diagram showing a single layer of light-colour coated glass mat cut with holes and backed with a non perforated glass mat backing having a same or contrasting colour. The exterior is above. 25 Fig 2: A diagram showing two layers of colour coated glass mat adhered together and die-cut with holes and backed with a non perforated glass mat backing as above. 6 Fig 3: A diagram showing three layers of colour coated glass mat cut with holes and backed with a non perforated glass mat backing as above. Fig 4: A diagram showing six layers of colour coated glass mat cut with holes and backed with a non perforated glass mat backing as above. 5 Fig 5: A cross-section approximately to scale of a completed panel, according to Fig 1, including a single layer of colour-coated glass mat cut with holes and backed with a non perforated glass mat backing and adhered to a glass fibre insulation board, the thickness of which is shown by the dashed line. Exterior is to the right; interior is to the left. 10 Fig 6: A surface view showing the appearance of an example pattern of die-cut holes made through a light-coloured glass mat, so as to expose a single layer of a coloured non perforated glass mat backing. Fig 7: Another pattern, as Fig 6, showing an irregular pattern of die-cut holes. Fig 8: A further pattern, as Fig 6, showing a regular pattern of die-cut slits. 15 Fig 9: A further pattern of slits, as Fig 8, where the non-perforated layer underneath has a light colour. Fig 10: Another pattern, as Fig 6, showing a regular pattern of die-cut triangular shapes. Fig 11. Panel including peripheral protrusions die cut into outer edge of the facing panel, typically 3 x 20 mm designed to self centre and align the panel in a T bar frame. 20 Protrusions hinge and are flexible to allow the panel to fit into the T bar frame. Fig 12, Panel, according to Fig 11, in place in a frame (vertical cross-section); showing how the protrusions make contact with the vertical web of the T bar frame. Fig 13. Sound absorbtion curve - perforated facing panel example 1 laminated to 50 mm glass fibre insulation board. Frequency rises to the right; absorbtion coefficient as 25 alpha-Sabin units rises to the top. Fig 14. Sound absorbtion curve - perforated facing panel example 2 laminated to wet felt mineral fibre board. Fig 15. Sound absorbtion curve - perforated facing panel example 3 with non porous 7 membrane backing layer as low frequency absorber Fig 16. Sound absorbtion curve - perforated facing panel example 4 laminated to 10 mm plasterboard INTRODUCTION 5 The inventor has developed a variety of surfaces (typically provided as panels) having an exposed or working surface made of one or more layers of glass fibre mats that are supported by including or being adherent to glass fibre boards or other such sound absorbing boards. The inventor has developed a number of dies for cutting shapes out of broad glass fibre mats of this type (see for example Figs 6-12) which technique results in 10 greatly increased reproducibility of tiles and layers within tiles. Although each new die for a customised design has of course to be created, the process is capable of being completed within a week of receiving an order. Further, there is the aspect of manufactured cost. A typical perforated wood, fibre cement, metal panel has a high manufacturing cost as a result of the cost of raw materials, inherent duration of manufacturing processes (such as while a 15 cement sets), the use of cutting or milling or routing in some cases. The present invention is expected to be of low cost. The invention may be provided ready to use, as stiff tiles including backing boards, or as tiles without a rigid backing for application to curved surfaces, or as large sheets or in rolls. The large sheets, or rolls, or tiles without backing sheets may be exported 20 and subsequently applied to appropriate backing boards made at or near a building site or the like. EXAMPLE 1: Figure 1 is a diagrammatic cross-section of an acoustic panel including a layer of glass mat 102 that is painted, dyed or otherwise coloured to become preferably black or 25 another dark colour - but the selection is a matter of preference rather than forming part of the invention. Manufacturers of these porous glass fibre mats include Owens Coming (see www.owenscorning.com) or Johns Manville (see www.jm.com); the thickness is in the range of 0.3 to 1.00 mm and the grams per square metre is 0.35 to 300 gsm (grams per square metre). Fig 5 is a cross-section to scale through an entire thickness of such a panel 8 from left to right on the drawing, showing the extent of a backing layer (inner surface: 101) at left and two surface layers at the right - the exposed side - as described in more detail below. The thickness of the backing layer varies according to requirements and in any case the present invention relates to the surface layers. Here, 104 indicates a portion of an 5 aperture cut through 103. At least one outer thin (typically 1 mm) layer 103 of a similar type of porous glass fibre mat is coated with an adhesive. The layer is impregnated, coloured, or lightly sprayed on an outer surface 105 typically using a light-coloured coating such as a white, grey or beige paint, so as to present a consistent appearance. Then it is cut so as to present a pattern 10 of shallow apertures. The perforated layer or layers are then adhered together and over the layer 102. 102 is another thin (typically 0.5 mm) layer of porous glass fibre mat that is the same or another colour. A preferred adhesive for this purpose is a "hot melt glue" resin or a water based PVA or PVU glue. Preferably all glues, paints, and any other organic materials use in these 15 tiles are low combustible or fire-retardant and will not easily burn or release toxic gases if they are heated. Each panel or tile may optionally have one or more further layers of a thicker glass fibre mat (typically 0.3 to 2 mm in thickness) again each provided with a glued surface so that the surface can be built up as a laminated structure. However extra layers are optional and depend on the acoustic performance required. 20 Some of a variety of adherent layers are shown for instance in Figs 2 (two layers), 3 (three layers, or 6 (six layers) in order to change the properties of the acoustic panel. One reason to have more layers is to provide a deeper, three-dimensional appearance to the perforations. More layers also have some effect on sound absorbtion which, in this type of acoustic tile may be tuned in relation to frequency and extent (see Figs 13-16 for test 25 results) Under the lowest (and most likely to be dark-coloured) layer there may be an optional layer of a non permeable polyester foil, vinyl foil or aluminium foil, one purpose of which is to act as a low frequency absorber, as is known in the relevant art, while reflecting higher frequency sound. 9 The apertures mentioned above are cut through the outermost layer (or layers) before gluing using a press and die or another appropriate cutting means, so that the lower colour will become visible to the outside through the apertures formed through the upper layer or layers after assembly. If the apertures are intended to be invisible then either all 5 mats may be the same colour, or no apertures are provided. (Alternatively the selected colours may be any two (or more) different colours including a dark outermost layer and a light underneath layer, giving an appearance of white spots in a dark background - like stars in the sky. The panels may exploit tri-coloured or even more colours in arrangements or patterns, again in this version of the invention, exploiting the masking properties of a 10 surface layer on underlying layers having other colours), For instance, an uppermost layer may include apertures that in turn expose deeper apertures cut through an intermediate layer having a third appearance, and so on, These apertures, which after assembly may be from about 1 mm to 5mm or more in depth, may (as in Fig 6) may simulate the appearance of holes of a prior-art acoustic tile but can be cut 15 in any desired size, shape or pattern including the regular pattern, as in Fig 6, that people expect to see in an acoustic panel. One preferred pattern (Fig 7) is pseudo-random and made up of circles of various sizes all selected and placed on the tile surfaces so that there is no relationship between the pattern as laid down and the boundary of any individual tile. The repeated slits of Figs 8 and 9 confer a different appearance and may have a directional 20 effect on sound waves, Fig 9 shows the appearance of a panel if the layer 102 having a relatively light colour. Fig 10 exploits the kind of cutting possible with a die, The boundaries of Figs 6 to 10 are arbitrary and do not represent actual panel edges. This invention has divorced the attribute of effective sound absorbtion from the attribute of appearance, whereas for prior-art perforated acoustic tiles, the type and 25 thickness of material and size and number of perforations were critical in achieving useful levels of sound absorption. In comparison with prior-art tiles the apparent holes are primarily for the sake of appearance. These holes play no great part in sound absorbtion, although it must be accepted that where the outermost layer has been removed a small amount of glass fibre mat has been lost. 30 These layers are supported by a backing layer of a glass fibre board which confers 10 an overall shape and thickness on the tile, and performs broad-band sound absorbtion. This facing layer may be adhered to a plaster board, mineral fibre board, rockwool board layer or any other substrate. Performance: Sound absorbtion curves. See Figs 13-16. 5 Facing panel - example 1. This is Fig 13. Example of the sound absorption curve for a facing panel of the invention comprising two layers of white glass mat facing perforated with 55 mm diameter holes at 100 mm centres backed with non perforated black glass mat and laminated to a 25mm glass fibre board tested in accordance with ISO 354 and ASTM C423-99 test method, E200 mounting. Specimen exhibited very high broad 10 band sound absorption curve, aW 1.00, NRC 0.95 typical of glass fibre board. Note that this performance is superior to any known prior-art perforated panel of a similar type. Facing panel - example 2: This is Fig 14. Example of the sound absorption curve for a facing panel of the invention laminated to a 15 mm wet felt mineral fibre board, tested in accordance with ISO 354 and ASTM C423-99 test method, E200 mounting. Specimen 15 exhibited moderate sound absorption at the high frequencies and poor absorption at the low frequencies, NRC 0.50 typical of wet felt mineral fibre board. Facingpanel - example 3: This is Fig 15. Example of the sound absorption curve for a facing panel of the invention including a non permeable vinyl foil layer and laminated to a 25 mm glass fibre board, tested in accordance with ISO 354 and ASTM C423-99 test 20 method, E200 mounting. Specimen exhibited moderate absorption in the low frequencies and poor absorption at high frequencies, aW 0.30 (L), NRC 0.40. This type would be useful as a low frequency panel absorber. Facingpanel - example 4: This is Fig 16. Example of the sound absorption curve for a facing panel of the invention laminated to a 10 mm plasterboard backing, tested in 25 accordance with ISO 354 and ASTM C423-99 test method, E200 mounting. Specimen exhibited poor absorption at low to high frequencies, aW 0.15, NRC 0.10. This type would be useful as a broad band sound reflecting panel; remembering that an acoustic panel is not simply a sound absorber. EXAMPLE 2 Tabs. I1 Another benefit of the manufacturing process using die-cutting of composite glass fibre mats tiles or panels is that their edges may be provided with combination retaining and locating tabs simply by modifying the knife. See Fig 11, showing the surface view of an acoustic panel (corner 103). The panel includes repeated peripheral protrusions 106 and 5 107 that are die cut so as to form part of the outer edge of the facing panel. Typically the tabs are about 3 x 20 mm in size. As well as helping to retain the panel, the tabs have a self centering and alignment function for the panel 103 when held in a frame such as the dependent ceiling T bar frame 108 and 109 as shown in the vertical cross-section of Fig 12, which shows that the outer edges of the die-cut protrusions (106 / 107) make continuing 10 contact with the vertical web of the T bar frame, so that they prevent the panels from shifting within the frame which would have the effect that the die-cut patterns would become misaligned. The slightly soft material helps to maintain contact. Protrusions may fold and are flexible to allow the panel to be fitted into a compatible T bar frame. The protrusions may be folded about their base. Their flexibility allows the panel to be fitted 15 into the frame. An installer may bend the entire panel to shift the protrusions past the edges of the frame and fit the panel into place. EXAMPLE 3 Manufacturing methods. Assuming that the sheets of glass fibre mats have been obtained in bulk from a manufacturer, probably in rolled format, and are either pre-coated or become coated on 20 appropriate surfaces with selected adhesives and optionally pigments, the specified shapes may be cut from the bulk material by one or more knives used against a bed in a press so that the knives will form the panel edges and will cut out the desired apertures. Optionally those knives that form the panel edges are provided with bends so that their cuts provide tabs. This process has advantages including speed and repeatability. Although a 25 numerically controlled cutting device may be programmed, in practice it has been found that the results are not very repeatable. Knives may be adapted to be mounted around rollers, for high-speed operation and bulk manufacture. It is more likely that custom cutting will be done with knives in a flat arrangement, if the volume of production is not great. Multi-layered mats may be glued together first then cut as a laminate, but alternatively may 30 be cut individually and then assembled because the degree of available precision is 12 sufficient to ensure that the holes stay aligned within a stack. Typical panel sizes are 600 x 600 mm, 600 x 1200 mm, and so on, according to local building practices. VARIATIONS Rather than be supplied in the form of individual panels as squares; rectangles, 5 hexagons or the like, the acoustically active surface as described in this specification may be supplied in bulk as large yet still manageable sheets, or possibly as rolls around a spool or former. Large sheets may be cheaper to make and easier to apply over large areas. Such bulk supplies may be transported over long distances then combined before use with locally made rigid and relatively heavy components. The backing may be added to 10 the decorative acoustic layer such as by a gluing process, near the place of use. The heavy components may, for example be conventional plaster board. This approach helps maintain a lower price. Other possible backing materials include glass fibre board, dry felt "rock wool" fibre board, dry felt glass fibre board, wet felt mineral fibre board, man-made mineral fibre board, or other vitreous fibre board, and other backing boards known in the 15 art. Sometimes an acoustic treatment is required to be laid over an existing rigid sheet such as a concrete wall. For that purpose also, the invention may be supplied as tiles or in bulk formats, without backing panels. If the tiles, panels or sheets are intended to be laid conformably over a curved 20 surface it is possible to make a curved, releasable former in the factory and to laminate several individual layers together over the former, taking care to maintain alignment of the pattern if the pattern is replicated through more than one layer. This variation is provided since the laminated sheets become stiff. While the use of a die for cutting out tiles with their edge alignment and 25 interlocking tabs has the advantage of speed, that method may be replaced by other cutting methods, including hand tools, but preferably computer-numerically-controlled knives, lasers, or water jets typically in order to create short runs, or to add decoration to a blank tile shape. 13 INDUSTRIAL APPLICABILITY and ADVANTAGES According to this alternative construction according to the invention, a range of improved acoustic panels having a markedly different visual appearance can be manufactured relatively easily and cheaply. Advantages include: 5 1. Excellent sound absorption capability that is not dependent on any particular perforated design; 2. Inherently decorative tiles; though without the cost of a printing process; 3. Significantly lower manufactured cost than traditional perforated hard materials; 4. Better performance and flexibility; the product can be attached to a gentle curve or 10 the lamination of sheets may be carried out on a former constructed in order to match a sharper curve (the laminates after gluing being inherently stiff) 5. Compact, light weight and easy to work, cut and trim; 6. Low embodied-energy material, that is less flammable; and 7. Special orders are easily met. 15 Finally, it will be understood that the scope of this invention as described by way of example and/or illustrated herein is not limited to the specified embodiments. Where in the foregoing description, reference has been made to specific components or integers of the invention having known equivalents, then such equivalents are included as if 20 individually set forth. Those of skill will appreciate that various modifications, additions, known equivalents, and substitutions are possible without departing from the scope and spirit of the invention as set forth in the following claims. 25 14

Claims (11)

1. An acoustic facing material, wherein the acoustic facing material is comprised of more than one layer of a felted mat of material having an outward or exposed surface layer; each layer of the material being comprised of a material selected from 5 a range including (a) felted glass fibre or other vitreous fibre, or (b) plastics fibre including without limitation polyester fibre, or (c) a blend of both a vitreous and plastics fibre material, and the layers are mutually adherent over their adjacent surfaces; the layered material being capable of exhibiting a predetermined sound absorbtion characteristic. 10

2. An acoustic facing material as claimed in claim 1, having an outward or exposed surface and an backing or supporting surface; wherein the outward surface layer has a first visible coloration and is configured by creating one or more apertures from the outward surface layer in order to partially expose a continuous underlying layer to which the outward layer is adherent; the underlying layer having a second visible 15 coloration; thereby providing decorative aspects without significantly compromising the acoustic properties of the material; the layered material being capable of exhibiting a predetermined sound absorbtion characteristic.

3. An acoustic facing material as claimed in claim 2, wherein an intermediate non continuous layer having a third visible coloration and one or more apertures within 20 said intermediate layer expose portions of an underlying layer having the second coloration.

4. An acoustic facing material as claimed in claim 2, wherein the outward surface layer is comprised of a plurality of outward relatively thin, adherent layers; each layer including one or more apertures; the layers being laid over each other with the 25 apertures in register, and the outward surface layer has a thickness of between I and at least 8 mm in thickness.

5. An acoustic facing material as claimed in any previous claim, wherein the material is provided as unit panels or tiles. 15

6. An acoustic facing material as claimed in any previous claim, wherein the material is provided in a bulk form.

7. An acoustic facing material as claimed in claim 5, wherein a series of tabs, nodes or protrusions are formed around the perimeter of each unit panel or tile; said series 5 being capable in use of serving as means to locate the unit panel or tile within a supporting frame in order to align the decorative perforated design from panel to panel and to achieve a uniform tessellated design.

8. An acoustic facing material or tile as claimed in claim 5 or in claim 6; wherein the acoustic facing or tile includes in sequence from the outward surface: an outward 10 discontinuous surface layer having a first coloration, a continuous underlying layer having a second coloration to which the outward layer is adherent; the acoustic facing material further including an optional backing of an acoustic tissue, an optional layer of a non permeable vinyl or other foil, and a backing board having an effective thickness and density; the backing board being selected from a range 15 including glass fibre board, "rock wool" fibre board, dry felt glass fibre board man made mineral fibre board, or other vitreous fibre board, and plaster board. and a backing board selected from a range including glass fibre board, dry felt "rock wool" fibre board, dry felt glass fibre board, wet felt mineral fibre board, man-made mineral fibre board, or other vitreous fibre board, plaster board and other backing 20 boards known in the art.

9. A die shaped in order to cut a tile according to claim 5 from a sheet of a glass fibre mat; the shape of the die incorporating means for cutting the series of tabs, nodes or protrusions around the perimeter of the tile.

10. A die as claimed in claim 9; wherein the shape of the die further includes means for 25 creating at least one aperture through the sheet.

11. An acoustic facing material substantially as herein described, with reference to the accompanying drawings. 16 The claims as defined in the invention are as follows 1. An acoustic facing material, wherein the acoustic facing material is comprised of more than one layer of a felted mat of material having an outward or exposed surface layer; each layer of the material being comprised of a material selected from 5 a range including (a) felted glass fibre or other vitreous fibre, or (b) plastics fibre including without limitation polyester fibre, or (c) a blend of both a vitreous and plastics fibre material, and the layers are mutually adherent over their adjacent surfaces; the layered material being capable of exhibiting a predetermined sound absorbtion characteristic. 10 2. An acoustic facing material as claimed in claim 1, having an outward or exposed surface and an backing or supporting surface; wherein the outward surface layer has a first visible coloration and is configured by creating one or more apertures from the outward surface layer in order to partially expose a continuous underlying layer to which the outward layer is adherent; the underlying layer having a second visible 15 coloration; thereby providing decorative aspects without significantly compromising the acoustic properties of the material; the layered material being capable of exhibiting a predetermined sound absorbtion characteristic. 3. An acoustic facing material as claimed in claim 2, wherein an intermediate non continuous layer having a third visible coloration and one or more apertures within 20 said intermediate layer expose portions of an underlying layer having the second coloration. 4, An acoustic facing material as claimed in claim 2, wherein the outward surface layer is comprised of a plurality of outward relatively thin, adherent layers; each layer including one or more apertures; the layers being laid over each other with the 25 apertures in register, and the outward surface layer has a thickness of between I and at least 8 mm in thickness. 5. An acoustic facing material as claimed in any previous claim, wherein the material is provided as unit panels or tiles. 15 6. An acoustic facing material as claimed in any previous claim, wherein the material is provided in a bulk form. 7. An acoustic facing material as claimed in claim 5, wherein a series of tabs, nodes or protrusions are formed around the perimeter of each unit panel or tile; said series 5 being capable in use of serving as means to locate the unit panel or tile within a supporting frame in order to align the decorative perforated design from panel to panel and to achieve a uniform tessellated design. 8. An acoustic facing material or tile as claimed in claim 5 or in claim 6; wherein the acoustic facing or tile includes in sequence from the outward surface: an outward 10 discontinuous surface layer having a first coloration, a continuous underlying layer having a second coloration to which the outward layer is adherent; the acoustic facing material further including an optional backing of an acoustic tissue, an optional layer of a non permeable vinyl or other foil, and a backing board having an effective thickness and density; the backing board being selected from a range 15 including glass fibre board, "rock wool" fibre board, dry felt glass fibre board man made mineral fibre board, or other vitreous fibre board, and plaster board. and a backing board selected from a range including glass fibre board, dry felt "rock wool" fibre board, dry felt glass fibre board, wet felt mineral fibre board, man-made mineral fibre board, or other vitreous fibre board, plaster board and other backing 20 boards known in the art. 9. A die shaped in order to cut a tile according to claim 5 from a sheet of a glass fibre mat; the shape of the die incorporating means for cutting the series of tabs, nodes or protrusions around the perimeter of the tile. 10. A die as claimed in claim 9; wherein the shape of the die further includes means for 25 creating at least one aperture through the sheet. 11. An acoustic facing material substantially as herein described, with reference to the accompanying drawings. 16