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Theme: paints and finishes

1 April, 2004

Architects need to be aware of an ever-growing list of considerations when specifying paints, fi nishes and sealants. While environmental and health concerns continue to drive changes in the formulation of such coatings - most notably forthcoming legislation demanding the removal of petroleum-based solvents from paint - issues such as accessibility for all represent an urgent challenge to designers as well as to manufacturers.This feature examines the issues facing the specifiers of paints and other surface coatings, and takes a look at some of the latest products on the market Paint it green Environmental and health concerns have prompted a number of changes in the formulation of paints and other coatings in recent years - most notably a reduction in the use of carcinogenic volatile organic compounds (VOCs) and the development of water-based paints that look and perform like oil-based ones.

'As an industry, ' he says, 'we are very much involved in the process of change, having representation on CEPE, the European legislative organisation which sets targets for VOCs. Evidence of our own commitment can be found in low VOC alternative formulations for finishes such as Crown Trade Low Odour Covermatt and Crown Trade Acrylic Eggshell, two products which achieve minimal VOC classification.' Paint manufacturers are being encouraged to develop water-based alternatives, says a spokesperson for Dulux R&D, as solventbased paints will effectively be banned in 2010. 'While Dulux Trade now offers a water-based alternative for every solventbased product in its range, it does recognise some technical problems with this, ' she adds.

'Firstly, it is diffi cult to get the same degree of durability with a water-based product, although these are starting now to come on to the market.' Dulux admits it has been difficult to develop a water-based alternative for gloss paints that gives the same degree of gloss finish, 'because solvent-based products remain open for longer, ie take longer to harden'. Consequently, it says, most waterbased alternatives are mid-sheen rather than high gloss. However, Dulux claims to have found a solution to this with its Aquatech gloss, using resin technology carried in water.

A more recent move, however, is to find alternatives to the resin used in paint, as most resin is derived from non-sustainable petroleum-based sources. Dulux is looking into making resins from more sustainable agricultural products such as starch.

Despite these efforts, environmentalists warn that not enough is being done to address the health and environmental problems associated with mass-produced coatings. They are concerned about the high embodied energy of water-based paints and the fact that petrochemical-based paints do not degrade.

Neil Rodger, sales and marketing director of Natural Building Technologies (NBT), says: 'Many paints are still relatively polluting and not good for the human environment, particularly vinyl-based emulsions.' Paints should always be microporous and breathable, he says, but for environmental paints to have credibility they have 'to meet acceptable usability standards'. Sometimes, Rodger admits, this means compromise: 'You'll need to use small quantities of chemicals to improve shelf life, for example - it's always a balance between usability and fitness for use.' 'The picture is a complicated one, ' agrees Jonathan Fovargue, sales manager of Construction Resources, a Londonbased supplier of ecologically responsible, sustainable building products and systems.

'Just being low-VOC and water-based is not the full story, as such paints require a whole load more chemicals to emulsify their ingredients into water.

'We sell only wholly natural paints with plant-based ingredients and a linseed oil binder. There's always a natural alternative to what's produced chemically, ' Fovargue insists. 'And whereas in the past colour was a limitation for natural paints, we can now offer colour to BS, RAL and NGS colour schemes.' Social housing, he says, is a strong driver for natural products, 'while private developers don't yet see their value'.

Fovargue says that enlightened social landlord, the Peabody Trust, recently specifi ed natural products for a new office building. 'Avoiding illness in its employees from off-gassing is worth more to them than a couple of quid on paint, ' he adds.

Construction Resources' impressive London showroom was designed by Devonbased Gale & Snowden, a firm specialising in low environmental-impact design, active in both the social housing sector and in the design of schools and community centres.

'We took the sustainable agenda on board 12 years ago, ' explains partner David Gale, 'and we always try and use healthy building products.' He fi nds that the specifi cation of eco-products is, increasingly, client-driven:

'Devon and Cornwall Housing Association chose us to build 35 mainly timber-framed units [at a site in Bideford] because they want to change the way they build.' Peter Smith, an authority on sustainable architecture and author of the book, Ecorefurbishment; a guide to saving and producing energy in the home (Architectural Press, 2004) notes that while an increasing number of architects are becoming committed to eco-friendly products, they're still very much in a minority. Since decorating firms are still not keen on eco-paints, he adds, they remain a niche market.

'We're going to need some legislation to drive things forward on a big scale, ' he says, 'as part of building regulations, for example, which need to be more holistically environmental.'

In case of fire Materials specified in the construction of new buildings or in the refurbishment of existing ones can play a crucial role in protecting lives in the event of a fire. Dr Steve Snaith, innovation and business-development manager for Dulux Trade, explains how paint is involved Fire regulations and surface coatings are effectively covered under the Building Regulations for new buildings or construction. Part B, and specifically Approved Document B, consider the impact of fi re on a building. Part B2 looks at the internal spread of fire on linings, and this includes paint. It is concerned with the ability of a lining to resist adequately the spread of fl ame and the rate of heat release, which is reasonable under the circumstances. Finally, B2 provides a classifi ation rating for materials from Class O to Class 3 that should be used in designated parts of a building.

In public buildings, common areas such as stairwells and lobbies should have the highest rating (Class O). Other rooms should be Class 1 or Class 3, depending on their size. In other words, common areas must have the most resistance to fire; the legislation is driven, after all, by the need to protect people, not buildings.

The classifi ation of coatings is determined according to two British Standard tests. Test BS476 Part 6 is a straightforward pass-or-fail test of heat release, while BS476 Part 7 gives a rating of how quickly flames spread across a surface.

Strictly speaking, Building Regulations apply only to new buildings or new construction. Existing buildings are governed by the Fire Precautions Act 1971 and subsequent amendments and specific industry legislation, such as that for schools.

The important thing about all the pieces of legislation and regulations, however, is that they all refer back to Building Regulations for guidance in best practice - it's about reducing risk, doing the best you can at a realistic cost.

Products from a number of manufacturers, including Dulux, have been certified to meet these tests.

The build-up of paint coatings can increase the rate of flame spread signifi cantly, and a proper risk assessment is needed prior to subsequent redecoration if the client wishes to reduce the impact of fi re. If a building already has paint on the wall and this paint is fl aking or is adhering poorly, it will need to be removed - because any subsequent coating will fail to prevent flame spread.

If an existing coating is sound, you may be able use one of a number of approved upgrade coatings that will slow down the spread of fl ame, going some way to counteracting the degradation caused by previous layers of paint.

Crucially, you must make sure that the product you're using has the correct certifi cation for the situation in which it is being used, and you should consult the manufacturer if in any doubt.

A clear vision There is more to specifying paint than choosing a colour as Linda Allmark, national specifi ations manager at Akzo Nobel Decorative Coatings, explains October 2004 will see the implementation of the fi al stage of the Disability Discrimination Act 1995 (DDA). Public or private organisations providing a direct service to the general public will have to make reasonable adjustments to their premises to ensure that their services are accessible to all, including people with physical and sensory impairments.

Regulations currently in place include Part M of the Building Regulations, which has recently been reviewed and now looks at access for all, and BS8300, the code of practice for the design of buildings for the convenience and use of people with disabilities. Both cover the use of colour and contrast, and provide guidance that can be used to meet some of the obligations of the DDA.

It is accepted that the introduction of colour contrast into interior design can improve signifi cantly a visually impaired person's way-fi nding ability and create accessible environments. Importantly, it is possible for designers, architects and facilities managers to use a wide range of colour schemes to create inclusive environments for the visually impaired that meet regulations, while at the same time retaining aesthetic appeal for fully sighted people.

The interior design of an inclusive environment begins with the isolation of the interior surfaces. By creating even a subtle contrast between the primary surfaces of a room (the fl oor, the walls, the door and the ceiling) navigation is significantly improved for the visually impaired. Interior design features such as coving, dado rails, architraves and skirting can provide further clues for way-fi nding by highlighting the areas where primary surfaces meet.

Research conducted at Reading University, which formed part of the basis for the DDA, concluded that a 30 per cent difference in colour, tonal contrast and luminance is necessary to meet the needs of the 90 per cent of people registered as blind who are actually partially sighted.

Selecting the right colour scheme is very important, but in practice it can be rendered ineffective if the light and reflectance of an interior are not considered too. Sources of light, whether natural or artificial, create areas of glare and shadow, and the effect of sporadic, strong lighting on a surface, and the subsequent shadow, can significantly change even the most intense colours. This can cause disrupting shapes and patterns across critical surfaces, such as openings to corridors and doorways, resulting in navigation problems for the visually impaired. Refl ectance can be reduced by avoiding shiny surfaces; matt or mid-sheen paint fi nishes will absorb light and reduce glare signifi cantly.

Few architects and architecture schools take an interest in colour, asserts colour consultant Jenni Little, choosing instead to regard it as the domain of the interior designer. And this, she believes, is a big mistake: 'While those architects who use colour well create great buildings, so often what we get left with are great spaces devoid of personality - pieces of sculpture, but not spaces to contain people.' Little, whose high-profile clients include Dulux, believes a 'judicious' use of colour can really improve a building for its inhabitants - increasing the apparent ambient temperature, for example, or creating a more relaxing or energising environment.

'Colour is the most powerful aspect of an interior, with the ability to influence the way we feel, think and behave, ' agrees Hans Ultee of Akzo Nobel's Aesthetic Centre in the Netherlands.

His colleague Vernon Kinrade, specification senior brand manager at Akzo Nobel Decorative Coatings, recognises a number of colour trends at the moment, 'many seemingly in contrast with one another'. One of the most interesting, he says, is the use of semi-translucent materials with lighting to achieve a subtle veiled appearance. 'This leads to colour palettes suggesting subdued variants of stronger colours - purples, greens and ambers.' He notes too, that in the aftermath of 9/11, 'people - families and organisations - are looking inwards to seek protection, cocooning'. This, he says, implies the use of comforting materials, as a contrast to the high-tech of the end of the last century, and colours that are of the Earth and derived from natural materials. 'It's a back-to-nature and back-to-basics approach.' For the interiors of public buildings, the trend is still very much for beiges and magnolias, says Neil Rodger, 'although on innovative buildings, there's a tendency for specifiers to be more adventurous'.

Jenni Little remarks that the recent trend for 'the naturals' - creams and whites - to be inspired by all things coastal, from pebbles to the sea itself, is now being superseded by a natural palette inspired by the Earth. 'We're seeing the emergence of naturals with green undertones, ' she says, 'and shades influenced by clays, marls, moss, lichen and heather.' She describes also how the current trend for painting woodwork and walls the same colour - a modern take on a Georgian practice - allows the eye to 'read a room without interruption', creating the illusion of space. And colours from this period are increasing in popularity, even for contemporary applications.

'There's a tremendous interest in historic or heritage colours for both new-build and refurbishment projects, ' says Little. 'These colours have a character not immediately apparent in contemporary ranges, a softness and an unsynthetic quality.' As for texture, Little remarks that chalky paints are increasingly popular: 'Dulux has a new very durable range of paints with an ultra-matt fi nish that don't come up shiny when rubbed.' There's also no longer a huge difference between woodwork and walls, with eggshell finishes being used more and more for both surfaces.

However, she notes a contrasting trend for urban apartments - a move to very highly reflective surfaces 'with darker, funky colours and a lot of shine'. But whatever the application, there's a large crossover between domestic and contract colour trends. The British public, Little asserts, 'are streets ahead of their European counterparts when it comes to colour confidence'.

PRODUCTS Coatings clean up A European consortium of private enterprises, research institutions and the European Commission's Joint Research Centre (JRC), is running a test programme for construction materials designed to soak up some of the noxious gases from vehicle emissions. These 'smart' construction materials, which include a surface coating, plaster, mortar and architectural concrete, are being developed as part of the PICADA (Photo-catalytic Innovative Coverings Applications for De-pollution Assessment) project. It is hoped they will help to reduce levels of nitrogen oxides (NOx gases) - gases which cause respiratory problems and trigger smog production, and other toxic substances such as benzene.

The clear coating - which could be pigmented - has been developed in the UK by the inorganic chemicals division of USowned Millennium Chemicals. It comprises a silicon-based polymer, polysiloxane, into which are embedded nanoparticles of titanium dioxide and calcium carbonate.

The idea is that NOx gases diffuse through the porous polysiloxane base and adhere to the titanium-dioxide particles. These particles absorb UV radiation in sunlight and use it to convert the NOx gases into nitric acid. The acid is then either washed away by rain, or neutralised by the alkaline calcium carbonate particles, which convert it to 'harmless quantities of carbon dioxide', water and calcium nitrate - which will also be washed away by rain.

A typical 0.3mm layer of the coating will contain enough calcium carbonate to last fi ve years in a heavily polluted city, according to Robert McIntyre of Millennium Chemicals. When the calcium carbonate has been exhausted, he adds, the titanium dioxide will continue to break down NOx, but the acid this produces will discolour the coating.

Natural choice for exterior timber Developed, tried and tested in Canada to give protection for homes built from cedar, Timba Dura from Blackfriar is a natural alternative to chemical-based products for protecting and reviving timber and other exterior wood on wooden buildings, outbuildings, cladding and A-frame structures.

Formulated using natural materials including beeswax and linseed oil, and coloured solely with permanent earth pigments, Timba Dura is said to deliver complete water-repellent protection, while at the same time allowing timber to breathe, expand and contract. It is designed to work in all weather conditions and extremes of temperature, without fl aking or fading.

Available in cedar, teak, redwood, dark oak, clear and black, it can be used on both fresh cedar and other hardwoods, as well as on weathered untreated hard and softwoods.

It dries to a semi-transparent sheen which, according to Blackfriar, enhances the natural grain and beauty of the timber.

'The natural earth pigments help prevent the greying and discoloration that would otherwise occur when wood is bleached by the sun, ' it claims. Blackfriar suggests a typical re-coating schedule of every five years, but maintains that little preparation is required for this. 'Timba Dura also has the advantage of a non-drip formulation, is easy to brush on to large vertical surfaces and, once dry, is completely harmless to both plants and animals, ' it claims.

The range is suitable for use on interior broadwall areas and joinery. 'Re-coatable' within four hours, says Heppenstall, it is ideal for projects where fast completion is important. In addition to its low environmental impact, the paint delivers a highly durable, satin-lustre washable fi ish. Available ready-mixed in white and magnolia, as well as all 1,232 colours in the Crown Trade Colour Collection, it has a spreading rate of 15m 2 per litre and is available in 1-litre, 2.5-litre and 5-litre packs.

Against radiation New from Ecos Organic Paints is a superconductive wall paint containing a non-toxic nickel pigment. This, the company claims, provides a shield against the ELF and EMR radiation produced by overhead electricity pylons, cellular telephone installations, TV and radio masts, and all kinds of electrical appliances, including computers, washing machines and mobile telephones.

According to Ecos, brick and concrete walls are no barrier to radiation, which has been linked to a number of illnesses. Its ELF/ EMR paint is dark grey, and designed to be over-painted or wallpapered.

Ecos has also launched a matt wall paint that, it claims, absorbs and neutralises volatile chemicals and pollutants, solvents and VOCs from the inside of a building down to a level of approximately one part per million. A 'special' silicate ingredient in Ecos Atmosphere is said to absorb and neutralise pollutants permanently, and is not exhausted with 'the average redecorating schedule of five years'.

On the wall Wall coverings manufacturer Muraspec, which specialises in commercial markets, has been working to reposition itself and reinvigorate the wall-coverings market.

Its research showed that architects found the materials increasingly irrelevant, and confusing to specify. Muraspec's response has been to rationalise its range, launch some new materials and provide a very logical method of specification, the Muraselector. This is a compact box containing a CD that allows one to select products by every criterion possible, and a set of samples and sample charts.

APPLICATIONS Innovative with render Perceptions in the UK are changing it seems, when it comes to the use of external renders.

Their association with crumbling council flats is fast being replaced in the public mind by one of smart new houses and pristinelooking public buildings, thanks in large part to high-profi le projects such as Ken Shuttleworth's Crescent House in Wiltshire and Daniel Libeskind's Imperial War Museum North in Manchester. Both these projects use coatings from German-owned Sto, which supplies a vast range of throughcoloured acrylic and silicate-based render systems in about several hundred shades.

Sto claims to have worked with all of the UK's 'top 100' architectural practices and has assumed a leading position in the UK market for external surface renders.

'Our business is growing, but it's still at a very small level compared with Germany, where acrylic renders are used on just about every type of building, ' says Sto marketing manager Denise Freeman.

She expects business to continue to grow, she adds, particularly on the high-density housebuilding front where, she says, Sto's insulating products 'are well ahead of the game on NHBC detailing'. Sto systems also 'go up very quickly', she adds, and the fact that they enable wall thicknesses to be reduced - by dispensing with the need for cavity walls - is particularly appealing to developers of expensive urban sites.

'Most architects prefer white renders, but a few are starting to use colours, ' says Freeman. She cites an ongoing project to construct fast-track high-density housing at Greenwich Millennium Village. Here, architect EDR has specified the use of several coloured renders, including orange and bright red. Where this project is groundbreaking, however, is not in the use of renders, but rather in the speed at which the apartments were constructed and the singleskin construction method. The facades of the steel-framed apartment block, designed in conjunction with EDR and contractor Taylor Woodrow, are coated with StoTherm Mineral M external wall-insulation system.

They comprise, beneath this, two sheets of internal plasterboard with a vapour membrane, a 150mm stud wall, and a layer of Pyroc sheathing board. 'The stud wall's void could have become a drum, ' says Sto technical consultant Roy Packman, 'so we filled it with an acoustic quilt, reducing the noise and increasing the U-value - which meant we could reduce the external installation.'

The system also eliminates cold bridging, he adds, while its fl exibility means that there's no need for vertical or horizontal movement joints.

'John Prescott said such projects had to be innovative, and this one certainly is, ' says Packman, 'and while we've completed plenty of office buildings using this technique, this is the first time it's been used for housing.' Finishes are on song A range of Dulux products has been used to complement and reproduce the effect of traditional materials such as limewash and wax in the new £1.6 million Song School at Chester Cathedral.

The construction of the building was monitored closely by English Heritage, the Cathedral Fabric Commission for England and local planning authorities, so it was vital that every detail was considered carefully.

The vaulted ceiling of the school has been plastered with lime and coated with a limewash specially tinted with a rose petal shade from the Dulux Trade palette.

Dulux Trade Eggshell, undercoats and gloss have been used to decorate door frames, architraves and skirting boards. The walls use Dulux Trade Supermatt, a permeable paint which lets them breathe, letting moisture escape from the plaster.

Dulux Trade tung oil has been used to protect oak window frames. The cast-iron gutters, downspouts and external window frames have been coated with the company's acrylated rubber, which protects against chemical and acid attack.

The Song School has been built on the site of a medieval monastery. Building work was carried out by Linford Building of Lichfi ld, Staffordshire, under the supervision of architect Arrol & Snell, and the interior decoration was the responsibility of DÚcor Limited. Director Paul Roome said: 'Huge attention has been paid to the detail in this project, and the sheer diversity of the Dulux Trade range has allowed us to find the right solutions to complement the original materials.'

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The Architects' Journal is the voice of architecture in Britain. We sit at the heart of the debate about British architecture and British cities, and form opinions across the whole construction industry on design-related matters