Paints – their ingredients and attributes


Understanding the main components that go into making a paint can help the painter gain awareness of two key things: understanding the potentially dangerous substances that can be present in some paints and learning what ingredients are necessary to make a successful homemade paint.

Any paint must contain the following:

•    A binder

•    A solvent or ‘carrier’

•    A pigment or ‘colour’ (optional)

The binder

The binder acts as a glue to stick the pigment (if used) to the wall’s surface. It must have the property of being able to dry out without losing its strength or binding power. It also provides the main body of the paint, and determines its texture and character.

The standard binders are normally synthetic chemicals such as acrylic and vinyl in synthetic paints. These are products of the petrochemical industry.

In traditional home-made paints and good quality modern ‘eco’ paints, the binders can include (among others) lime, clay, milk protein (casein), egg, flour starch and linseed oil.

The solvent or ‘carrier’

The solvent serves to dissolve and hold both the pigment and the binder in suspension within a spreadable, liquid form, until the paint is applied. It is therefore known as the ‘carrier’. Once the paint has been applied, the solvent should evaporate to leave the dry binder and pigment intact on the wall. Many solvents release volatile organic compounds (VOCs) into the atmosphere as the paint dries and the solvent evaporates. This is what creates the typical smell of a freshly painted room. These VOCs are responsible for the majority of the environmental and physical damage created by paints.

For synthetic paints, the standard solvent is mineral turpentine, produced from crude oil.

In traditional home-made paints and good quality, ‘eco-paints’, solvents consist mainly of vegetable-based turpentine, from renewable plant sources such as citrus oil (made from orange peel), pine resin, water, alcohol and linseed oil.

The pigment or ‘colour’

The addition of a pigment to paint gives it colour and can serve to hide or cover any surface blemishes in the wall. There are many different types of pigment available, which can broadly be characterised into natural and synthetic.

Modern synthetic paints are made up solely of synthetic pigments, which provide strong colours. Most ‘natural’ paints are made with earth pigments, which provide subtle, earthy hues.

Other ingredients:

Some paints (traditional, ‘eco’ and synthetic) also include additional ingredients to help fulfil specific requirements.

Examples include:

•    Preservatives and anti-fungal agents, such as borax and clove oil (safe and natural) and formaldehyde (toxic and dangerous).

•    Fillers to bulk the paint out, such as chalk, clay (natural and safe) and titanium dioxide (safe, but very destructive in its production methods).

The dangers of synthetic paints

Perhaps the most illuminating example of the dangers of synthetic paints from a health perspective is that in Denmark, ‘painter’s’ or ‘solvent’ dementia is a fully recognized disease. Also, as far back as 1987, the World Health Organisation’s international agency for cancer research officially stated that occupational painters have a 40% increased risk of contracting cancer. Greenpeace has directly linked the increase in volatile organic compounds in the atmosphere to a decrease in the reproductive functions in human and wildlife populations.

On an environmental level, US research has concluded that VOCs in paint production create levels of smog in the atmosphere almost equal to that created by vehicle exhausts. It has also been proven that when one gallon of paint is thrown away and seeps into the earth, it has the ability to pollute 250,000 gallons of drinking water. Synthetic paints can have an impact on:

•    Human health

•    The health of the environment and wildlife

•    The health of buildings made out of porous materials, including traditional buildings

Human health

The direct effects of paint on human health come predominantly from the solvent element within the paint. Unless water is used, all solvents used in conventional paints emit volatile organic compounds (VOCs) into the atmosphere as the paint dries. These VOCs combine either with each other or with other volatile chemicals present in the atmosphere to produce very toxic chemicals. The most dangerous levels are found in the air whilst the paint is drying, and when the paint smell is at its strongest. However, some VOCs can offgas from paint for many years, even when dry. If VOCs are inhaled into the body, they can create a plethora of minor and serious health problems to both the painter and to those inhabiting the painted space. The American Lung Association, for example, has linked contact with VOCs to eye and skin irritation, headaches, muscle weakness, lung disorders, nausea, irreversible liver and kidney damage and cancer.

The two most common solvents used in acrylic and emulsion paints, toluene and xylene, can potentially cause long term foetal damage and developmental problems. Many synthetic paint manufacturers have moved to eliminate solvents and hence VOCs from their paints by using water as a solvent. However, this has generally meant that a large number of equally dangerous chemicals, such as glycol ethers, have been added to replace the functions previously carried out by the synthetic solvents. Hence a can of paint that is labelled ‘low’ or ‘zero’ VOC is not telling the whole story.

Synthetic paints are literally made up of a concoction of different chemicals, each having their own long list of potential related illnesses. Some of these are minor and short-lived, like headaches and nausea, others can be long-term and chronic, such as allergies created from statically charged, dust-attracting vinyl binders. Still others can be highly life-threatening, such as glycol ethers, asphalt and polyurethane, which can create cancers.

Damaging paint chemicals can enter the body through inhalation, ingestion, and direct contact with the skin. Once in the body, some of these chemicals are known to be bio-accumulative. This means that they can build up in the cells and remain there, even to be passed onto future generations.

The environment and wildlife

Owing to the interconnected nature of all things, whatever impacts the environment also affects all living and breathing inhabitants of the planet, and hence the two cannot be separated. Environmental degradation from conventional paints occurs at all stages of its life cycle:

•    The production of the paint itself, through the extraction and production of the ingredients.

•    The toxic gases released from the paint once used.

•    The afterlife of the paint – the ability of painted materials to safely biodegrade, the problems associated with the safe disposal of paint leftovers, and the pollution created by the run-off when cleaning brushes.

Paint production

The bulk of conventional paints are made up from products from the petrochemical industry, such as vinyl and acrylic. Oil dependency must be diminished as it is a non-renewable resource and is made with an incredibly energy-intensive process.

Titanium dioxide, which is a white pigment used in all synthetic paints to increase coverage and opacity, is one of the most energy-intensive and damaging of all ingredients used. Titanium dioxide is a natural mineral. To make it pure white, it must be purified by a process of cleaning with acids. These toxic acids are generally dumped into the environment. All these processes contribute vast amounts of CO2 emissions into the atmosphere.

The release of toxic gases

The airborne VOCs released into the atmosphere once the paint is on the wall and begins to dry, accounts for 9% of all airborne pollutants and contributes to ground level ozone. The American Environment Protection Agency (EPA) rated paint as being amongst the top sources for indoor air pollution.

The afterlife of the paint

Any material that has been coated with a toxic paint will not easily or safely biodegrade into the ground, painted wood being the foremost example. All synthetic paints are toxic to wildlife in any quantity. Furthermore, the synthetic chemicals present in their formulations are persistent and will take millions of years to break down into safe components in the environment. This also includes any paint residue flushed into the environment through washing brushes.

Building health

All synthetic paints are non-porous, and do not breathe. They are also brittle and inflexible. Any paint used on a building made out of porous materials requires a paint that is compatible in terms of its porosity and ability to expand and contract in line with the natural movements of the building. If this is not observed, it can lead to problems with trapped moisture in the walls, flaking paint, damage to and possibly failure of the plaster/render, and even the walls themselves.

Why are synthetic paints so widely used?

It is hard to fathom why synthetic paints managed to replace and virtually eliminate the use of traditional paints, all within the space of a mere 60 years. This is especially hard to understand when it is considered that home-made traditional paints were generally made with safe, local materials that were compatible with the buildings they were being applied to. Hindsight can only be gained through time, and clearly convenience is a powerful lure. Most people were ready to relinquish what they saw as a laborious process, requiring a range of tools and ingredients. Most of the world was ready for all that was convenient, predictable, consistent and less labour-intensive. The new, modern paints were obviously well marketed and perceived as being convenient and easier to apply (one coat of conventional paint versus three coats of limewash). People were ready to be liberated from the necessary repainting required every few years. But times are changing again, and the growing awareness of the dangers of synthetic paints is encouraging a revitalised interest in making paints from scratch. This enables the painter to know exactly what ingredients are involved, as well as allowing a sense of personal satisfaction from being involved in the whole process. For those who prefer to be safe, healthy and life-supporting, but who want the convenience of a good quality, ready-made paint, it is also possible to look to the new generation of ‘eco-paints’.

Pre-manufactured ‘eco’ paints

The definition of what entails an ‘eco’ or ‘natural’ paint is fairly vague, and can be quite confusing. Most of the major conventional paint manufacturers now produce a line of paint, which they claim to be either ‘low’ or ‘zero’ VOC, ‘breathable’, and sometimes even ‘natural’ or ‘eco’. Care should be taken before purchasing one of these paints. However, there is an ever-increasing number of companies producing very good quality, versatile and authentic ‘natural’ paints. For a paint to live up to the name of being ‘eco’ or ‘natural’, the company producing it should adhere to the following principles:

•    Minimising impact on the environment Renewable and biodegradable ingredients. Minimal or no off-gassing of toxic, ozone-depleting chemicals.

•    Eliminating danger to human health Non-toxic and even life-enhancing ingredients, such as odour-absorbing clays and pleasantly smelling essential oils. Minimal or no off-gassing of toxic VOCs.

•    Maximising the health of a building High vapour permeability, allowing buildings to breathe and thus help prevent damp and mould.

The most important test lies with the willingness of the company to provide comprehensive ingredient lists and production information that states exactly what materials are included in the paint and how they were produced. This is especially important for chemically-sensitive individuals, who may even be allergic to some of the ‘natural’ ingredients included. For example, some of the non-synthetic solvents used, such as citrus oil or vegetable turpentine, may also trigger allergies, although they are not nearly as damaging in the long-term as their synthetic counterparts. For this reason it is also necessary to ventilate any internal spaces being painted, even if using a safe paint. On the whole, it makes the most sense to opt for a paint company that uses simple technology and simple ingredients, drawn from traditional recipes and know-how. Also it is best, where possible, to support companies that are producing locally or at least within your country.

Currently, many of these ‘natural’ or ‘eco’ paints are slightly more expensive than their conventional counterparts. This is obviously because the market is still relatively small and therefore production is on a smaller scale (which is, however, quite often a good thing), and because the raw materials being used are of good quality and therefore more expensive.

To save on expense, and so that you know exactly what is going on your walls, it is possible to opt for making your own paint. This can be an easy and satisfying process. The rest of this chapter provides recipes and guidelines for producing ‘eco-friendly’, healthy, beautiful and cost-effective paints and washes.

Home-made natural paints

Most home-made natural paints are simple and easy to make. Many of them require inexpensive ingredients, which are easy to get hold of. Many of these ingredients include everyday household grocery items, such as wheat flour paste and skimmed milk. Other more specialist ingredients, such as linseed oil, casein powder and lime, are easily obtained from specialist suppliers.

The majority of the home-made paints described below consist primarily of a base (or binder) of either lime, earth (clay) or milk protein (casein powder). Certain additional ingredients can be added to these basic paints and washes, to enable them to function better in certain circumstances. Water is the primary solvent.

Paint preferences: In order to improve the welfare of living beings, buildings & the environment, try to use:

1.  Home-made limewashes, clay paints, distempers, casein paints with natural earth pigments.

2.  Mineral paints, and water and plant-based paints.

3.  Paints made from plant and mineral ingredients using natural solvents.

4.  Water-based synthetic paints.

5.  Solvent-based synthetic paints.

Pigments

All the home-made paints described below can be used in their natural state to produce a white or buff coloured paint. It is also possible to add colour through the use of pigments. The pigments can also be blended together to create unique and personalised colours. There are many different types of pigments, and not all are suitable for use in lime-based paints and washes. Also, some are highly toxic and energy intensive/polluting to produce. Broadly speaking, pigments can be categorised into:

Natural earth and mineral pigments

Natural earth pigments are literally derived from different coloured earth and rocks. They are first extracted and mined, secondly either crushed and ground, and then sieved. They are either used in their raw form or heated to produce different shades. The different colours are attributed to the different minerals present, such as iron oxides and manganese. Natural earth pigments normally dictate the specific regional colours of an area, as they will have been mined locally. This is why many traditional towns and villages sit so comfortably within their surrounding environment, as they are literally painted with materials from the earth and rocks around them.

The earth pigments are the most suitable for use in home-made paints because they are generally the safest and are the most compatible with lime. Lime is very alkaline, and some pigments will react negatively with this alkalinity. The most compatible, or ‘lime-fast’ pigments are those composed of the metal oxides, such as the yellow, red and brown ochres, raw and burnt siennas and umbers. All reputable lime suppliers and pigment specialists should be able to advise on the suitability of a pigment for use in a limewash. The mineral content of the natural earth pigments also makes them more resistant to the effects of ultraviolet light, meaning that they are less likely to fade over time.

The colours produced from the natural earth pigments are generally soft, subtle, earthy, and less bright than the synthetic pigments. Their crystalline structure causes light hitting the paint surface to be reflected in different directions, meaning that paints made with natural pigments provide a uniquely vibrant finish of unsurpassed richness.

Natural earth pigments are found in rocks and soils around the world in a range of colours.

Natural earth pigments need to be ground down to a fine powder before being added to paint.

Natural animal or plant-based pigments
Plant or animal dyes can be used as pigments in paints, but they are not recommended because they will fade quickly with exposure to light.

Synthetic pigments

These are made synthetically from chemicals to either replicate the natural earth pigment colours, or to extend the range of colours naturally available. Many pigments are derived from natural but very toxic heavy metals, such as cadmium and chromium, or from products of the petrochemical industry.

Many of these pigments are very stable and lime-fast, such as cobalt blue, emerald green, Indian red and cadmium yellow. They are thus suitable for use in limewashes. However, they are more toxic and energy-intensive to extract than their natural earth counterparts.

Preparation of pigments

Most pigments can be purchased ready to use in a fine powdered form. Suppose using personally extracted coloured clays or pigments, or the pigment is coarse. In that case, it is necessary to grind it into a fine powder using a pestle and mortar, grinding mill or a rolling pin onto a hard surface. Dampening the material prior to grinding will prevent dusting and will assist with the grinding process. The more finely ground the pigment, the more evenly dispersed it will be in the paint, and hence the more uniform the finish achieved. If the pigment is not finely and evenly ground, streaks of pigment may appear on the wall.

Sculpture by Roxanne Swentzell.

The ground pigment is best if it is soaked for 24 hours, or overnight in a small amount of water, to fully break down the particles of pigment before being added to the paint base. Alternatively, the pigment can be mixed with warm water in a sealed jar and shaken vigorously prior to being added to the paint. If the pigment does not dissolve easily in water, it can be mixed with a small amount of alcohol, such as vodka or another white spirit. Once added to the paint base, soaking the mixture for an hour or two will further help to disperse the pigment throughout the paint.

The fine powders of pigments can be hazardous when inhaled, so always use a mask and work in a well-ventilated space when handling.

Sampling

All pigments behave differently when added to a paint base, so it is always advisable to carry out a few sample patches on the substrate to be painted, before committing it to the entire wall. It is also very difficult to anticipate the final colour of the pigmented paint before the paint has been applied to the wall and fully dried. The colour in the bucket of the wet paint will be many shades darker than the dried paint on the wall, and the only way to accurately arrive at the desired colour is to carry out numerous tests. Take notes on each recipe, as it is easy to forget the exact proportions used in each mix.

Generally speaking, the more pigment added, the deeper the colour. However, a threshold amount can be added to a certain amount of paint base, beyond which the paint will be weakened, creating a powdery paint. This threshold is based on the percentage of pigment that can be held by a given amount of binder. This amount is 7.5-10% of pigment by weight of the binder. This threshold can also be ascertained through the test batches: if the dried paint or wash easily dusts off, the threshold may have been exceeded.

Mixing colours

Colours get deeper with each consecutive coat. Different and unique colours can be achieved by mixing various pigments together. Too many colours, however, will produce muddied tones, so stick with 2-3 colours at most. The standard colour wheel, used to provide insight into how different colours work together, can be a useful tool for helping to create a personalised colour palette. The general principles for mixing different colours are:

1.  Start off with a single pigment and add consecutive colours, one at a time.

2.  Start with the weakest colours first, then add the strongest.

Lime

Lime is the principal ingredient in limewash (it acts as the binder). Generally, a non-hydraulic lime putty is preferred for its pure white colour and because it produces a better consistency limewash. Natural hydraulic limes can be used where damp conditions prevail. However, the strength of the lime used should correlate with the strength of the plaster/render and wall substrate below (see Chapter 3). An NHL2 is generally best in these circumstances for making exterior limewashes. The cheaper hydrated ‘builders lime’ will not produce a good limewash, and its use is not recommended.

A well made limewash produces a highly effective, simple, inexpensive and beautiful finish. It creates a soft, matte effect that compliments and enhances old and new buildings constructed out of breathable materials. Like all building traditions utilising lime, it has been used for thousands of years to protect and beautify internal and external walls. Due to its mildly antiseptic qualities (because of its alkalinity) it has a rich agricultural history: it was used to help keep domestic and farm outbuildings healthy and safe. In many cultures around the world, the yearly limewashing of public and private buildings was an important part of spring cleaning rituals (and still is, in some parts of the world).

Like a lime plaster or render, a limewash dries and cures into a water-insoluble finish via carbonation (as well as hydration if using a natural hydraulic lime). It reacts with carbon dioxide in the atmosphere to revert back to calcium carbonate, its original chemical form (see Chapter 3). No toxic fumes (VOCs) are released from the limewash as it dries out. Limewash is often said to produce a unique surface ‘glow’, especially when natural earth pigments are added. This is a result of the crystals of calcite (CaCO3) that are formed during carbonation. These crystals absorb light and then reflect it back in duplicate. This is known as a ‘dual refractive index’.

The main benefit of using a limewash, especially on buildings made out of porous materials, is its high vapour permeability and breathability. This is due to its micro-porous structure, which ensures that any moisture absorbed into the outer skin of the limewash or plaster/render can quickly and efficiently evaporate. This allows the walls to dry out, and hence prevents the accumulation of excessive and harmful moisture build-up within the structure. This also makes limewash the ideal finish for use in remedial situations in old buildings where dampness is an issue. Limewash will also successfully heal minor shrinkage cracks in the plaster/render and an evening out blemishes in the wall surface, especially when numerous coats are applied to build up protection. Limewash is also flame-resistant and will prevent the spread of flames. It can be made washable if made well, and is not affected by ultraviolet light.

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