GB2365860A

GB2365860A - Cementitious surfacing composition including a polymeric additive and a method of application using a stencil

Info

Publication number: GB2365860A
Application number: GB0120010A
Authority: GB
Inventors: Frederick James Adams
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-08-18
Filing date: 2001-08-16
Publication date: 2002-02-27
Also published as: GB0020361D0; GB0120010D0

Abstract

A composition for forming a decorative finish on a substrate comprises a cementitious material and a water thinnable polymer emulsion or resin, such a polyvinyl acetate or styrene-butadiene rubber. Preferably the cementitious material comprises 90-99% wt. and the water-thinnable polymer 1-10% wt. of the mixture. The composition is may be applied to walls using a stencil to give a surface texture resembling bricks and mortar. A first layer of the surfacing composition may be applied to the wall using a spray. A stencil is affixed on top of the first layer before spraying a second layer of pigmented composition over the stencil. The pigmented composition is allowed to partially harden before the stencil is removed to reveal a surface texture with a contrasting colour pattern.

Description

TITLE: PROCESS FOR COATING WALLS DESCRIPTION The present invention relates to a method for applying a decorative finish to a surface, and particularly to a finishing composition. There are many methods available in which a decorative finish is applied to a floor or wall surface to enhance the appearance of the surface. These met:nods include cementing or otherwise attaching thin slices of material, onto the substrate such as a wall to give the impression of a brick or stone wall. Alternatively, a tape design can be applied to the wall to act as a szencii, and a coating can then be sprayed over the wall surface. Once the coating has started to harden, the tape can be removed, leaving a decorative pattern on the wall. The wall could be dyed or treated with a coloured stain prior to application of the tape and coating, so that the

pattern on the wall le-t by the tape will contrast with the applied coating. Such methods are time consuming and the finish quality depends or: the skills of the person carrying out the work. The applicant is aware of a stencil system and process for applying a decorative coating atop a substrate as disclosed in U.S. Patent Number 5,243,905. The stencil system includes a plurality of stencils which are interconnectable and which are laid on top of the substrate prior to covering with a liquid cement-like acrylic Ccating. Once covered, the stencils are removed to leave a decorated surface relief on the substrate, perhaps simulating stonework, brickwork, tiling or the like. The present anblicant has noted that there is a need for a cement itiouscomposition for use as a coa-ing or finishing preparation which has very particular properties. The coating must remain plastic prior to application, stick to the substrate when applied, set hard rapidly and allow easy removal of a stencil during the hardening process. In accordance with a first aspect of the present nvention, there is provided a finishing-preparation additive for combining with a cementitious material to create a surface finishing composition, comprising a water- thinnable polymer emulsion or resin. In one embodiment of the present invention, the water-thinnable polymer emulsion or resin comprises water soluble polymerised vinyl acetate [CH,COOCH=CHz]r (PVA).

In another embodiment, the water-thinnable polymer emulsion or resin comprises styrene -butadiene rubber (SBR) perhaps in particulate or powder form. The PVA or SBR gives the cementitious material the desired consistency during application, possibly by forming cross-links between different chains in the polymer. The desired consistency is that which allows the cementitious material to adhere to a wall, when for example applied thereto with a cement gun, without slippage. The PVA or SBR may also increase the hardness of the finished material. The proportion of PVA in the water based polymer emulsion may fall within a range of values. In one embodiment, the proport' ons by weight of PVA and water in the emulsion are 5% PVA dissolved in 95% water. Tn accordance with a second aspect of the present invention, there is provided a composition for forming a decorative finish on a substrate, comprising a cementitious material and a water-thinnable polymer emulsion or resin. For the purposes of the present application, the term "cementitious material" includes any material which reacts with a water based solution upon mixing to produce a semisolid or solid material which is self-supporting. An example of such a material is Portland cement.

in one embodiment of the invention, the cementitious material comprises a mixture of cement powder (e.g. Portland cement), sand, and a dry pigment for colouring

the material. In another embodiment, the proportions by weight of the constituerts are 32% cement powder, 64% sand and 4% pigment. The water- thinnable polymer emulsion or resin may be selected from the group consisting of a water-soluble polymerised vinyl acetate (PVA) and styrene-butadiene rubber. The proportions of polymer emulsion or resin and cement mixture may fall within a range of values, although, in an embodiment, 25 kg of cement mixture are combined with 2 litres of water based polymer emulsion. In accordance with a third aspect of the present invention, there is provided a method for forming a decorative coating on a substrate, comprising: providing a composition as hereinbefore defined; mixing the composition with water to form a cement mixture; and applying the cement mixture to a substrate. For the purposes of the present application the term "substrate" includes any surface to which a decorative coatinq can be applied. of such surfaces are concrete walls, plasterboard covered stud walls and plasterboard ceilings. In certain cases, a primer layer may be acplied to the substrate to improve adhesion between the substrate and the cement mixture. A method of application comprises spraying the cement mixture onto the surface usina a cement crun. An embodiment ot" the invention will now be described, by way of example, with reference to the accompanying

drawing, figure 1, which shows a method for applying a decorative coating to a wall, in which: A water based polymer emulsion cement additive (10) is mixed with a cementitious material (11) containing pigment I (12) to form cement composition I (13). A thin base layer of composition I (13) is then applied as a primer layer to a substrate (14). Applied base layer of Composition I (13) is then left to harden. A stencil (15) is affixed to the base layer on substrate (14) using an adhesive (16) which forms weaker bonds with the wall than those within the s-encil or wall, such as 'Blu-Tack'. Subsequently 2 kg of a water based polymer emulsion cement additive (10) is mixed with 25 kg of a cementitious material (17) containing pigment II (18), which contrasts with pigment I (12), to form cement composition II (19). A thicker layer of composition II (19) is then applied atop the primed substrate (14) and stencil (15). After the layer of composition II (19) has hardened enough for the stencil (15) to be removed without spoiling the decorative effect, the stencil (15) is removed to reveal a surface texture with a contrasting colour pattern resembling grouting on the substrate. The surface texture formed by Composition II is then left to harden fully. In another embodiment, the thin base layer of composition I (13) is replaced with a pigmented primer solution alone, such that the wall is just coated with a ccloured primer layer. In yet another embodiment, after application of the

second thicker layer of the cement composition and prior to removal of the stencil, a third 'fleck coating' may be applied consisting o= a very chin layer of yet anot:~:er contrasting coloured composition as herein before disclosed. In another embod=.m.ent of the present invention, the finishing material herein before disclosed may be applied direct to the surface to give a plain decoration, without using a stencil to form. a contrasting colour decoration. In any of the embodiments herein before described the final coating gives a matt finish to the vertical substrate.

Claims

CLAIMS 1. A surface finishing additive for combining with a cementitious material to create a surface finishing composition, comprising a water-thinnable polymer emulsion or resin.
2. A cement additive according to claim 1, in which the water-thinnable polymer emulsion or resin is selected from the group consisting of water-soluble polymerised vinyl acetate (PVA) and styrene -butadiene rubber.
3. A cement additive according to claim 2, in which the PVA is present in an amount between 0.1% and 50% by weight, balance being water.
4. A cement additive according to claim 2, in which the styrene-butadiene rubber is a powder.
5. A composition for forming a decorative finish on a substrate, comprising; a cementitious material; and a water- thinnable polymer emulsion or resin.
6. A composition according to claim 5, comprising proportions by weight of: 90-99% cementitious material and 1-10% water-thinnable polymer emulsion or resin.
7. A composition according to claim 5 or 6, in which the water-thinnable polymer emulsion or resin comprises watersoluble polymerised vinyl acetate (PVA).
8. A composition according to claim 5 or 6, in which the water-thinnable polymer emulsion or resin comprises styrene butadiene rubber.
9. A method for forming a decorative coating on a

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substrate, comprising: providing a composition according to one of claims 5 to mixing the compositiowith water to form a cement mixture; and applying the cement mixture to a substrate.
10. A method accordina to claim 9, in which the mater_al is applied to the substrate using a cement gun.
11. A method acco_ d,@no to claim 9 or 10, further comprising: affixing a stencil to the substrate prior to applying the cement mixture.
12. A method according to claim 11, further comprising applying a 'fleck coating' over the applied cement mixture prior to removal of the stencil.
13. A method according to any one of claims 9 to 12, in which the substrate is a wall or ceiling;
14. A composition for forming a decorative finish on a substrate substantialiv as herein before described.
15. A met. od substant-'ally of forming a decorative finish to a substrate as herein before described with reference to, and as illustrated in, the accompanying drawing.