What do you look for in a paint? Performance and aesthetics, for sure. But what about sustainability? Environmental and health benefits? Is it possible to tick all the boxes? Until relatively recently, the answer was no. But a new generation of paints has changed all that. Colin Jones, technical sales advisor at Earthborn, explores the options and takes a closer look at external masonry.
Taking their cues from traditional paints of the past, a few manufacturers have developed advanced techniques to blend the best of the old with the new. Gone are the solvents and acrylics of conventional paints. In their place are environmentally friendly materials blended with advanced technology to maximise performance.
Today, you can specify water based paints that combine outstanding performance with sustainability. There is no longer a compromise to be made in terms of durability, breathability, aesthetics, weather resistance, environmental credentials, health or sustainability.
As a relatively new phenomenon, there is a lot of confusion in the market about ‘natural’ or ‘eco’ paints. So, what do you need to look for?
Breathability
It is now widely recognised that breathability is vital to preventing problems with moisture in walls.
Many walls, even in relatively modern buildings, can suffer from damp, be it rising, penetrating or due to other causes. With nowhere to go, damp will eventually blow paint and plaster or render off a wall and damage the underlying material. The more breathable the paint, the better it will safeguard the fabric of walls.
Practicality
In addition to breathability, it’s important to consider ease of use, covering power, durability and, in the case of exterior paint, a tough weather resistant finish.
Aesthetics
Paint is, of course, a highly visual material. So it’s important to find a range that offers pleasing finishes and colour palette. Some eco friendly paints now offer the full BS4800 colour range.
Health and the environment
The two potentially harmful components in paint are volatile organic compounds (VOCs) and acrylic softeners, both of which are given off during painting and for many years after application. Harmful ingredients can also find their way into drains when washing out brushes and groundwater when paint tins are disposed of in landfill.
As well as being harmful to the environment, they can cause chest complaints, aggravate allergies and cause sick building syndrome.
High levels of VOCs generally are associated with oil based paints, but they are found to varying degrees even in water based paints. The EU limit for paints to be classed as minimal VOC is 30g/L. However, this is relatively high compared to the value that environmentalists recommend and which can be found among the new breed of paints. It is advisable to seek out those containing a maximum of just 0.5g/L VOC.
Sustainability
Paint can impact on a project’s sustainability: not just its environmental ratings but, most importantly, whether it will safeguard the fabric of a building for the future. A durable, breathable paint can prevent damage, thereby significantly reducing the maintenance lifecycle of walls.
When specifying for sustainability, the most stringent standard is the EU Ecolabel. It certifies that products make minimal impact on the environment throughout their lifecycle – during manufacture, use and disposal – and do not harm the health of people using or living with them.
Options for external masonry
Exterior masonry is probably the toughest test of all for paint as it needs to be weatherproof, good looking and durable. Generally, the options are seen as either acrylic based, conventional paints or traditional limewash. But there’s a third option, silicate paint, which offers a highly effective alternative.
Film forming paints
Conventional, acrylic based masonry paints form a film that prevents water ingress, but also prevents a wall from breathing. Micro-porous film forming paints are a recent innovation, containing inorganic fillers to enable some breathability. However, both are susceptible to cracking due to differential thermal movement between the paint and substrate. Their lifespan tends to vary from five to 15 years.
Limewash
Limewash is the traditional, breathable option for exterior masonry. But its longevity is poor, requiring regular repainting, and it is a harsh material for decorators to use.
Silicate paint
Widely used in mainland Europe, silicate paints have been around for more than 100 years. They contain potassium silicate which penetrates the masonry and forms a tough chemical bond with underlying materials. The bond contains pores that are large enough for the wall to breathe but small enough to prevent water ingress.
The result is an extremely durable, weather resistant yet breathable paint that can significantly reduce the maintenance lifecycle of walls. Today’s silicate paint systems perform for 15 years and more. They can be used on most mineral based surfaces including stone, brick, concrete, pebbledash, plaster and render.