GB2629342A

GB2629342A - Surface covering

Info

Publication number: GB2629342A
Application number: GB2305708.6A
Authority: GB
Inventors: Nathan Paul
Original assignee: Duzst Ltd
Current assignee: Duzst Ltd
Priority date: 2023-04-18
Filing date: 2023-04-18
Publication date: 2024-10-30
Also published as: GB202305708D0

Abstract

A method of forming a surface covering comprises: preparing a sheet material composition of liquid or pourable form by mixing a powder with a carrier matrix; introducing the sheet material composition into a mould shaped to form a sheet material 18; applying a backing layer to the sheet material composition in the mould 20; allowing the sheet material composition to set to form a sheet 22; and demoulding 24 the sheet to provide the surface covering. The carrier matrix may be polymeric, or a material composition comprising latex, rubber caoutchouc or combinations thereof. The powder may be granules, flakes, chips, files and/or particulate material such as fine dust or silicate material such as mica; or may be a ground material made from natural or waste materials such as grounds or dust from stone cutting operations, charcoal, organic materials such as leaves, tea dust, egg shell and other materials. The mould may comprise discrete contour layers resulting in a corresponding contour of the sheet to achieve a textured or pattern effect. The surface covering may be a prefabricated cover sheet material or wallpaper sheet such as used for cladding or decorative purposes. A surface covering is also provided.

Description

Surface covering

Field of the Invention

The present invention relates to a surface cover, specifically to a prefabricated cover sheet material suitable as wall cover. More specifically, the invention relates to a profiled material sheet and method of forming a profiled material sheet that can be manufactured to a length of 2 to 3 metres or more, in the form of a sheet sufficiently self-supporting for manual handling in a practical setting, so as to be suitable as an internal wall surface cover.

Background

Prefabricated cover panels or wallpaper sheets are used as cladding and for decorative purposes for interior design and decoration of walls and sometimes ceilings, floors, or furniture surfaces. To cover relatively large areas, typical approaches include the use of tiles or rigid panels, which require installation, alignment and fixation, or the use of flexible sheets such as wall paper.

The application or installation of such coverings can require specialist knowledge and skill to ensure good alignment particularly when covering larger areas such as a wall from ceiling to floor.

The present invention seeks to provide an alternative wall covering solution.

Summary of the Invention

In accordance with a first aspect of the invention, there is method of forming a surface covering suitable for attachment to a surface, as defined by claim 1. The method comprises: preparing a sheet material composition of liquid or pourable form using a powder and a carrier matrix; mixing the powder with the carrier matrix to form the sheet material composition; providing a mould shaped to form a sheet material; introducing the sheet material composition into the mould; applying a backing layer to the sheet material composition in the mould; allowing the sheet material composition to set to form a sheet; and demoulding the sheet to provide the surface covering.

The surface covering is understood to be a component of sheet form, or thin panel form, wherein the expression sheet may encompass a flexible panel or pliable panel. In accordance with embodiments, the surface covering is a solid made from a pliable or flexible material such as latex, rubber or the like having a sheet thickness of no more than a few millimetres. As such, the surface covering may be pliable or flexible, e.g., so as to be provided in roll form, and so as to allow it to be applied to a surface by unrolling.

The surface covering is considered to be a component that is suitable for attachment to a surface underneath in that it is sufficiently self-supporting so as to be suitable for handling during decorating, e.g., rolling and unrolling to cover a wall.

The sheet material composition may be formed in the manner of a suspension, comprising powder suspended in a matrix material. The powder may be provided in the form of ground material. Specifically, the ground material may be made from natural or waste materials, such as grounds or dust created as by-product from stone cutting operations, charcoal, organic materials such as leaves, tea dust, egg shell, and other materials.

The powder may have a high degree of homogeneity so as to appear uniform under visual inspection. Alternatively, the powder may have a lower degree of homogeneity or be of heterogeneous nature so as to appear textured under visual inspection. The powder may be provided in the form of granules, flakes, chips, files, and/or particulate matter such as fine dust or silicate minerals such as mica. The powder may comprise a mixture of different materials and a range of different particle sizes and particle shapes. The powder may comprise or constitute a pigment. The method may comprise maintaining the powder at a temperature suitable for mixing with the carrier matrix. The method may comprise soaking the powder to facilitate mixing it with the carrier matrix. The method may comprise sifting the powder to achieve a desired particle size distribution.

The sheet material composition is preferably liquid, or sufficiently pourable, to allow a suspension to be mixed to a desired degree of homogeneity, and to allow it to be introduced into the mould.

The backing layer may be applied onto the sheet material composition in the mould. It was found that the handling of the sheets may be facilitated by adding a backing layer. A suitable backing layer may provide a support for a non-woven sheet material composition. The backing layer may be of woven form, of pressed fibre form, or other suitable network structures. The backing layer may be a composite fibre material, such as a mesh, fleece or felt. The fibre based composition may be a fibre-reinforced polymer, including carbon, glass, and other types of fibre compositions. However, this is not necessarily a requirement in all embodiments of the invention.

It is preferable for the backing layer to have material properties that complement or otherwise support the sheet. For instance, the backing layer may comprise an adhesive layer for affixing the sheet via the backing layer to a surface. The backing layer may comprise sound damping or antifungal properties. The backing layer may have a particular fire rating. Several different forms of suitable backing layers will be known to a skilled person.

The backing layer may be fibrous, porous or of similar composition that allows air exchange, or "breathing" through the backing layer. In this manner, the backing layer may be applied before the drying process is concluded, to allow it to be embedded into the sheet material composition.

In some embodiments, the method comprises using a polymeric material as the carrier matrix.

The carrier matrix may be a non-woven material to provide a fluid or pourable composition suitable for moulding, curing and demoulding when mixed with the powder.

In some embodiments, the method comprises using a material composition comprising latex, rubber, caoutchouc, or combinations thereof, as the carrier matrix.

The carrier matrix is preferable a binder material suitable for mould forming. Prior to the admixture of a powder, the carrier matrix is preferably colourless, transparent or of a light colour. However, this is not necessarily the case in all embodiments. It is preferable for the carrier matrix material to be able to dry out without extensive shrinking, curling or cracking. In trials, it has been found that latex and latex based compositions are suitable carrier matrix materials. Other suitable materials are rubber, caoutchouc, and similar materials.

It is preferable for the material to have a relatively high softening point so as to be useable as wall covering in warm rooms, including shop windows, near radiators, and similar environments. The carrier matrix material may comprise a hardening composition so as to provide a suitably high softening point. In embodiments, the softening point is no lower than 80°C, 100°C, 120°C, 140°C, 160°C, 180°C, 200°C, 250°C, 300°C, 350°C or no lower than 400°C.

In some embodiments, providing a mould comprises forming a profiled positive, and forming a profiled negative by applying a mould material to the profiled positive, letting the mould material set, and separating the profiled positive from the profiled negative to provide the profiled negative as the mould.

By "profiled" positive, a positive is meant that has a surface that is other than a flat comprised of a single level surface. The profile of the positive is understood to correspond to the profile to be reproduced in the sheet. In this manner, a mould shape can be formed as a negative complementarily to the desired profiled positive.

In some embodiments, forming a mould comprises using 3D printing to create a mould.

The mould may be formed by additive manufacturing methods, specifically additive deposition methods comprising a curable material deposited in printable form and allowed to set to form a mould device.

A mould of this form may be created directly from a software instruction without reliance on a physical positive shape, although such a positive shape could be used, e.g. scanned, in the creation of a computer design model that is used for the creation of 3D printing instructions.

The mould is preferably made from a material composition suitable for temporary deformation to facilitate demoulding. An exemplary material for a mould is silicone material, although other suitable materials may be used. Silicone materials in particular are available as 3D printing medium, which would allow a 3D printed silicone mould to be manufactured.

In some embodiments, the mould comprises a base of generally planar extension comprising a plurality of discrete contour levels, wherein two adjacent discrete contour levels are set apart from each other by a level-to-level distance of at least 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm or at least 0.6 mm.

In some embodiments, the mould comprises a base of generally planar extension comprising a plurality of discrete contour levels, wherein two adjacent discrete contour levels are set apart from each other by a level-to-level distance of no more than 1 mm, 1.5 mm, 2 mm, 2.5 mm, or 3 mm.

By "contour level", a region or area is meant that has the same height, e.g. spacing from a base of the mould or spacing from a deeper or higher region of the sheet.

The surface of each contour level, and of the base, may be generally planar. In practice, the surface of one or more contour levels and/or of the base may comprise a texture, which may be tolerated or may be added deliberately.

It will be appreciated that contour levels are distinguished from texture, which may be randomly distributed. In contrast, contour levels are provided by a defined, practically consistent level-to-level distance defining two or more discrete levels. To provide an illustrative example using representative distance numbers, a first contour level may be a base level at 0 mm height, a second contour level may be at a level of 0.5 mm above base level, and a third contour level may be at a level of 0.9 mm above base level and/or 0.4 mm above the second contour level.

The inventor was able to achieve a good level of precision of contour levels by combining laser guiding or other similar tools, and by first creating a positive from a wood prototype from which the mould is cast. In this manner, moulds of several square meter size, e.g. 1 m x 3 m area, having profiles with sub-millimetre level-to-level distances, were achieved.

In aspects of the invention, a surface of the sheet is contoured and comprises two or more discrete contour levels, or height regions. During the development of the invention, it was found that the difference between contour levels, or level-to-level distance, may not need to be much in order to achieve a strong visual pattern effect.

This is believed to be the case at least in part because the different contour heights result in different thickness of the sheet material composition, which affects the appearance, such as the intensity of the colour, of the sheet material composition. In this manner, a cover sheet material can be created with two or more hues of a colour by applying a single type of sheet material composition.

It will be appreciated that the planar extension of different contour levels may be generally plane-parallel to the base and/or other contour levels. However, this is not necessarily the case in all embodiments, and some embodiments may comprise an oblique planar orientation. This is believed to provide a gradient hue effect.

In some embodiments, the mould comprises at least two discrete contour levels.

In this manner, a sheet appearing to comprise two different colour hues can be created.

In some embodiments, the mould comprises at least three discrete contour levels.

In this manner, a sheet appearing to comprise three different colour hues can be created.

The profile may comprise a pattern of different regions, or "islands", that are laterally spaced apart and each have a corresponding contour level.

In some embodiments, the method comprises drying the sheet at least partially prior to demoulding.

The drying may be carried out using suitable equipment, such as an oven. In a preferred embodiment, the sheet is allowed to dry in a free environment, e.g. to air-dry.

The drying process may improve the embedding into, or attachment of the backing layer on the sheet.

In some embodiments, the method comprises continuing to dry the sheet after demoulding.

After a sufficiently long drying time in a mould, the sheet may be sufficiently consolidated to allow it to be manipulated for transfer to a drying rack. In this manner, a mould can be freed for reuse.

In some embodiments, the method comprises placing the sheet on rack structure suitable for air drying.

The sheet, whether in a mould or demoulded, may be placed on a rack structure. The rack structure may comprise multiple regions or shelves, for instance for 10 or 20 sheets, or more, each spaced apart by a stack height permitting ventilation for air drying.

In some embodiments, the method comprises drying the sheet for at least 24 hours.

It will be understood that the drying time depends on the choice of material composition of the carrier matrix, composition of pigment powder, thickness of the sheet, and other factors such as ventilation, temperature and humidity levels of the drying environment.

In accordance with a second aspect of the invention, there is provided a surface covering as defined in claim 14, the covering having been manufactured according to the method of any one of the embodiments of the first aspect.

In some embodiments, the surface covering comprises a top layer of generally planar extension comprising a plurality of discrete contour levels, wherein two adjacent discrete contour levels are set apart from each other by a level-to-level distance of at least 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm or at least 0.6 mm.

In some embodiments, the surface covering comprises a top layer of generally planar extension comprising a plurality of discrete contour levels, wherein two adjacent discrete contour levels are set apart from each other by a level-to-level distance of no more than 1 mm, 1.5 mm, 2 mm, 2.5 mm, or 3 mm.

In some embodiments, the surface covering comprises at least two discrete contour levels or at least three contour levels.

In some embodiments, the surface covering has a length of no less than 1 metre.

The sheet may be made to a length of at least 1 metre, 2 metres, 3 metres, or more. In embodiments, the sheet is made to length sufficient for a single sheet to cover the vertical extension of a room, e.g. from ceiling to floor. Most residential dwellings are expected to have a room height of no more than three metres. Some residential and commercial settings may require longer sheets, e.g. of 4 or more metres, which is possible with a sufficiently dimensioned mould.

In some embodiments, the surface covering has a width of no less than 20 centimetres.

The sheet may be made with a width of at least 20cm, 30cm, 50cm, or at least 1 metre. Due to the flexible property of the sheet, it may be transported in roll form. To this end, it is believed that a width in the region of between 1 to 2 metres provides a practical size determining the length of a roll of material for transport. However, other width and length dimensions may be used depending on application requirements.

In some embodiments, the backing layer comprises a mesh or fibre based composition.

The backing layer may be partially or fully embedded in the sheet material.

In some embodiments, a level-to-level distance between a highest planar contour level and a lowest planar contour level is no more than 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, 5 mm, 4 mm, 3 mm, 2 mm, or 1.5 mm.

A surprising effect noted during the development of the embodiment was that a sheet may be made relatively thin, in the region of 1-3 mm, with multiple contour levels. This achieves a few practical effects, namely that a sheet material can be made thinner, and is therefore easier to dry and more likely to be pliable or flexible for handling. However, this is not an inherent requirement of all embodiments. If desired, a thicker sheet may be formed.

In some embodiments, the edges between different contour levels are of stepped form. 5 Stepped edges have been found to provide a visually prominent boundary between contour levels, which may also correspond to the hue or shade of a profile. The stepped edges may be considered a discontinuous transition between two contour levels. To facilitate demoulding, an edge of stepped form may comprise a taper or sidewalls oriented at an oblique angle, i.e. other than perpendicular relative to the base of the sheet. However, if flexible moulds or sheet material compositions are used, and due to the shallow step height, demoulding may be facilitated without reliance on tapered edges.

Features described in relation to any one or more of the embodiments of the first aspect may be combined with, or used for the manufacture of any one or more of the embodiments of the second aspect.

Description of the Figures

Exemplary embodiments of the invention will now be described with reference to the Figures, in which: Figure 1 shows a sequence of exemplary steps of a method of the invention; Figure 2 shows a prototype positive profile; Figure 3 shows a prototype mould corresponding to the Figure 2 profile; Figure 4 shows an intermediate sheet product; Figure 5 shows a prototype profiled sheet according to an embodiment; Figure 6 shows a mould for a wall covering sheet; Figure 7 shows a wall covering sheet made to the Figure 6 mould; Figure 8 illustrates a racking for drying step; Figure 9 illustrates the Figure 7 sheet in a bent configuration; Figure 10 illustrates an alternative example of a profiled sheet; Figure 11 illustrates an exemplary illustration using two profiled sheets; and Figure 12 is a schematic illustration of a section through a portion of a sheet.

Description

Referring first to Figure 1, this shows steps of a method 10 in accordance with an aspect of the invention for the manufacture of a surface covering. In step 12, a powder material is provided and prepared, e.g., brought to an appropriate temperature to be suitable for mixing with a carrier matrix. In step 14, the powder is mixed with a carrier matrix to provide a sheet material composition.

In step 16, a mould is provided that comprises discrete contour layers. Step 16 may be carried separately to steps 12 and 14. In an optional step 17, the mould or portions thereof, for instance the base of the mould, is lined with some of the powder material and an optional thin layer of carrier matrix material. The optional step 17 may be carried out to ensure positioning of some of the solids of the powder near the surface of the surface covering, or to expose some of the solids on the surface. Step 17 may be omitted if the presence of solids on the surface of the covering is not desired.

In step 18, the sheet material composition is introduced into the mould. Depending on the composition of the material, it may be poured or spread on the mould. The sheet material composition is relatively liquid and will be allowed to set by drying. In step 20, a backing layer is applied to the sheet material composition. The backing layer may be of fibrous or mesh form, such that some of the sheet material composition may seep into or through the backing layer, which achieves an embedding effect.

In step 22, the sheet material composition is allowed to set by drying. The drying process in step 22 may carried out until the sheet is sufficiently solid for demoulding. The method may proceed to step 24 before the sheet is dried out completely.

In step 24, the sheet is demoulded from the mould. The sheet has some flexibility that assists with the demoulding. Likewise, the mould may be of a flexible structure such that the sheet and/or mould may be temporarily deformed, e.g. by bending, for demoulding.

In an optional step 25, further powder material may be applied to the free surface of the sheet (i.e., the face opposite the side provided with a backing layer). Optional step 25 may be carried out instead of, or in addition to, an optional step 17. Step 25 may be carried out if additional powder material is desired to be visible on the surface. Step 25 may be carried out before the sheet has been dried fully, to assist with embedding, or "rubbing in" of powder into the sheet.

In step 26, the sheet is allowed to dry further after demoulding, if required. The drying process may be an air drying process lasting several hours or days. The drying process may, alternatively, be carried out in an oven or other suitable drying equipment.

In an optional step 28, additional finishing steps may be carried out. The surface of the sheet may be covered wholly or in part with one or more layers of a sealant or sealing layers. The surface of the sheet may be coloured with additional patterns if desired. Other surface finishes such as polishing or roughing may be applied.

Furthermore, the sheet may be cut to a desired shape or size, and/or may be provided with holes to accommodate fixtures such as sockets, access covers, handles and the like. Due to the relatively thin dimension of the sheet, it is relatively easily cut with a good degree of precision.

Different finishing procedures may be carried out as part of step 28. Not all of the finishing procedures of step 28 are necessarily carried out as part of the sheet manufacturing process. Some of the finishing procedures may be carried out at the time of installing the surface covering.

Referring now to Figures 2 to 12, these show illustrations of components used in the manufacture of a surface covering sheet, and example embodiments. Figure 2 illustrates a profiled positive 30 comprising a body 32. The body 32 comprises a generally flat base with (here:) four lower regions 34a, 34b, 34c, 34d that are recessed deeper than (here:) four higher regions 36a, 36b, 36c, 36d. The level of the four lower regions 34a-d is generally the same and constitutes a first discrete contour level. The level of the four higher regions 36a-d is also the same and constitutes a second discrete contour level. The level-to-level distance between the first and second discrete contour levels is in the region of 1 millimetre.

10 15 20 Figure 3 shows a mould 40 made from silicone as imprint of the profiled positive 30. The mould 40 comprises a mould body 42 with generally flat profile comprising contoured regions that are discretely spaced apart (in a level-to-level direction), corresponding to the contour levels of the body 32. As such, the mould body 42 comprises a plurality of (here:) four lower regions 46a, 46b, 46c, 46d that are recessed deeper than (here:) four higher regions 44a, 44b, 44c, 44d.

Figure 4 shows the mould 40 and applied to it an amount of sheet material composition 50a. The sheet material composition 50a is applied in pourable form and allowed to set. Prior to setting, the sheet material composition 50a is covered with a fibre sheet 58 to embed it with the composition 50a.

Figure 5 shows a demoulded sheet 50 made from the demoulded sheet material composition 50a. The sheet 50 is contoured corresponding to the contoured profile levels of the mould 50 (Figure 3) and the profiled positive 30 (Figure 2). As such, the sheet 50 comprises a generally flat base with (here:) four lower regions 54a, 54b, 54c, 54d that are recessed deeper than (here:) four higher regions 56a, 56b, 56c, 56d.

Figures 2 to 5 show steps and components used for the manufacture of a prototype sheet having a size of about 30cm x 30cm.

Figure 6 shows a larger mould 60 comprising a mould body 62 provided with a profiled pattern having (here) two different contour levels. The mould has a size of about 1m width x 3m length, to allow a sheet of corresponding dimensions to be made.

Figure 7 shows a second sheet 70 constituting a surface covering, after demoulding. The second sheet 70 has a size corresponding to mould 60, of about 1m width x 3m length. This allows the second sheet 70 to be used as a unitary component to cover a length (e.g., a height of a wall) of up to 3 metres. The second sheet 70 is provided with a profiled pattern corresponding to the profiled pattern of the mould body 62, with recessed regions 74 and higher regions 76.

The second sheet 70 may be in a condition just after demoulding. Depending on the composition of the carrier matrix and the sheet material, and depending on the sheet thickness and environmental factors such as temperature and humidity, a sheet of this size may require several hours or days to dry fully.

Figure 8 shows a drying rack arrangement 80 comprising a plurality of shelves 82, here provided in the form of pallets stacked on top of each other, that allows a relatively large number of large surface coverings to be dried simultaneously. The second sheet 70 has a thickness of only a few millimetres, in the region of 2-3 millimetres, and is sufficiently flexible to allow it to be rolled or folded. Figure 9 shows the sheet 70 hanging over a support frame, its body in a bent configuration 72a.

Figure 10 shows a third sheet 90 having a comprising a sheet body 92 a profiled pattern with recessed regions 94 and higher regions 96. The third sheet 90 has a size of about 1m width x 3m length. The lower and higher regions have the some contour level. Comparing Figures 7 and 10, the method allows different sheet designs for relatively large area sheets to be manufactured repeatedly.

Figure 11 shows a test installation 78 using two sheets 70a, 70b as a wall paper. It will be appreciated that the sheets 70a, 70b extend over the full height of the walls underneath in a unitary manner, without joint lines. The flexible character of the sheets allows the sheets to be applied by unrolling them on the wall, e.g. from top to bottom or from ceiling to floor.

Figure 12 illustrates a schematic side view of a sheet structure 100 to visualise an embodiment with more than two contour levels (here: three contour levels). The sheet structure may be manufactured by the method 10 described above. The sheet structure 100 comprises a backing layer 120 embedded with a base layer 112 at a first interface 102. The base layer 112 comprises a first contour level 104 of generally planar extension. The first contour level 104 may be provided with a texture, or may be smooth. Protruding above the first contour level 104 is a first contour layer 114 having a generally even thickness (contour height) corresponding to a second contour level 106. Above the second contour level, a further, second contour layer 116 protrudes having a generally even thickness (contour height) corresponding to a third contour level 108. The edges of the second contour layer 116 are constituted by a step 124 providing a defined boundary between the second contour layer 116 and the first contour layer 114. Likewise, the edges of the first contour layer 114 are constituted by a step 122 providing a defined boundary between the fist contour layer 114 and the base layer 112. Although illustrated as layers for the purpose of emphasising the contoured levels, the base layer 112 and the first and second contour layers 114, 116 of the sheet structure 100 are unitary and made up of the same sheet material composition. The thickness (height) of the layers may be in the region of a millimetre or less. For instance, the height of the sheet structure 100 may be no more than 2 or 3 millimetres.

The sheet material composition used for the manufacture of the sheets 50 (Figure 5), 70 (Figures 7, 9, 11) and 90 (Figure 10) is relatively homogenous, yet provides a visually discernible pattern aligned with the different thicknesses of the contour levels.

The different hues or shades may be made more prominent by appropriate selection of the backing layer, for instance by selecting a bright (e.g., white) backing layer or a darker (e.g., black) backing layer.

It will be appreciated that the description hereinbefore is exemplary in accordance with embodiments the invention and that a wide range of modifications and alterations may be made thereto without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS: 1. A method of forming a surface covering suitable for attachment to a surface, the method comprising: preparing a sheet material composition of liquid or pourable form using a powder and a carrier matrix; mixing the powder with the carrier matrix to form the sheet material composition; providing a mould shaped to form a sheet material; introducing the sheet material composition into the mould; applying a backing layer to the sheet material composition in the mould; allowing the sheet material composition to set to form a sheet; and demoulding the sheet to provide the surface covering.
2. The method according to claim 1, comprising using a polymeric as the carrier matrix.
3. The method according to claim 1, comprising using a material composition comprising latex, rubber, caoutchouc, or combinations thereof, as the carrier matrix. 20
4. The method according to any one of the preceding claims, wherein providing a mould comprises forming a profiled positive, and forming a profiled negative by applying a mould material to the profiled positive, letting the mould material set, and separating the profiled positive from the profiled negative to provide the profiled negative as the mould.
5. The method according to any one of the preceding claims, wherein forming a mould comprises using 3D printing to create a mould.
6. The method according to any one of the preceding claims, wherein the mould comprises a base of generally planar extension comprising a plurality of discrete contour levels, wherein two adjacent discrete contour levels are set apart from each other by a level-to-level distance of at least 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm or at least 0.6 mm.
7. The method according to any one of the preceding claims, wherein the mould comprises a base of generally planar extension comprising a plurality of discrete contour levels, wherein two adjacent discrete contour levels are set apart from each other by a level-to-level distance of no more than 1 mm, 1.5 mm, 2 mm, 2.5 mm, or 3 mm.
8. The method according to claim 6 or 7, wherein the mould comprises at least two discrete contour levels.
9. The method according to any one of claims 6, 7 or 8, wherein the mould comprises at least three discrete contour levels.
10. The method according to any one of the preceding claims, comprising drying the sheet at least partially prior to demoulding.
11. The method according to any one of the preceding claims, comprising continuing to dry the sheet after demoulding.
12. The method according to any one of the preceding claims, comprising placing the sheet on rack structure suitable for air drying.
13. The method according to any one of the preceding claims, comprising drying the sheet for at least 24 hours.
14. A surface covering produced according to the method of any one of the preceding claims.
15. The surface covering according to claim 14, comprising a top layer of generally planar extension comprising a plurality of discrete contour levels, wherein two adjacent discrete contour levels are set apart from each other by a level-to-level distance of at least 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm or at least 0.6 mm.
16. The surface covering according to claim 14 or 15, comprising a top layer of generally planar extension comprising a plurality of discrete contour levels, wherein two adjacent discrete contour levels are set apart from each other by a level-to-level distance of no more than 1 mm, 1.5 mm, 2 mm, 2.5 mm, or 3 mm.
17. The surface covering according to any one of claims 14 to 16, comprising at least two discrete contour levels or at least three contour levels.
18. The surface covering according to any one of claims 14 to 17, having a length of no less than 1 metre.
19. The surface covering according to any one of claims 14 to 18, having a width of no less than 20 centimetres.
20. The surface covering according to any one of claims 14 to 19, wherein the backing layer comprises a mesh or fibre based composition.
21. The method according to any one of claims 6 to 9, or the surface covering according to any one of claims 14 to 20, wherein a level-to-level distance between a highest discrete contour level and a lowest discrete contour level is no more than 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, 5 mm, 4 mm, 3 mm, 2 mm, or 1.5 mm.
22. The method according to any one of claims 6 to 14, or the surface covering according to any one of claims 14 to 21, wherein the edges between different contour levels are of stepped form.