Five Things: Ecologically Sound Paints
Updated: Sep 12, 2021
Most paints in use today are made from fossil fuels in some form. This can be in the vehicle (the binder medium the pigment is suspended in), the solvent (if the binder is too viscous to be used neat), the pigment, or the additives to change the drying behaviour or other characteristics. They can give off unpleasant or injurious fumes while drying, and in building terms can affect how a structure behaves with water vapour (‘breathability’), exacerbating problems with damp. In use, they can also ‘off-gas’, releasing toxic chemicals into the air we breathe. All these things are more or less nasty, and can in extreme cases be very unhealthy or dangerous, contributing to so-called ‘sick building syndrome’.
In no particular order, we’ve collected here five examples of types of paint that don’t exhibit these effects, and are made from sustainable materials. They will look different and behave differently from Trade Emulsion, which we see as a good thing. The variation of a natural pigment is more alive and rich than an acrylic surface, but an investigation into the delights of imperfection will have to wait for another day. They are more expensive too, partly because they are being compared to unsustainably cheap products, and also they are made from less common materials with lower demand. Sometimes the production processes are simply more involved.
Casein (milk) Paint
One of the most ancient paints, it is known in the earliest Ancient Egyptian murals. Casein is precipitated from milk with enzymes in a similar process to cheese-making. It binds the pigments and behaves similarly to a distemper, though with more wear-resistance. Supplied in a tin, or as a powder, with the latter it is very easy to mix colours on site as the pigments come powdered too! After mixing with water, it can be painted onto most surfaces, working particularly well on plaster and wood, including furniture, drying to a matt, chalky finish. It becomes more resistant with age, and can be varnished or buffed.
Rose of Jericho produce a variety of traditional paints in wonderful colours in Dorset, including this casein distemper.
Another old paint style coming back into prominence, silicate paints are made from waterglass (sodium silicate), some lime and mineral pigments and fillers. As they dry and cure, they react with the carbon dioxide in the air to produce a robust, durable coating that remains breathable. Ideal for painting masonry without compromising vapour permeability of the structure. They can also be used inside and have an appealing, soft matt finish.
Mike Wye protected and decorated this Somerset house with lime render and silicate paint.
Linseed oil paint
One of the largest categories, as linseed oil has been used for thousands of years. The flax plant has been of central importance to numerous cultures in Europe and Africa, because of its range of uses. Construction, making linen, food, and the numerous uses of its oil. Linseed oil paint is durable, non-toxic and extremely easy to maintain. High gloss finishes are possible, especially on woodwork. Modern paints form films on top of the surface and require re-painting often as they decay. Linseed oil has a very low surface tension so is able to penetrate into the wood by capillary action. It prevents the wood from drying out and cracking as well as protecting the surface. This is why it’s so important to oil cricket bats in winter. It biodegrades so doesn’t leave harmful residues, and when the colour starts to fade it can simply be wiped over with fresh linseed oil. ‘Stand Oil’ is linseed oil that has been heated to about 300°C in the absence of air, and held there for some days. It partially polymerises, and becomes more elastic, with a greater ability to self-level, and less of a tendency to yellow. Stand Oil paints are particularly good for external use.
The Linseed Paint Company makes paint in Glasgow, with a very informative website.
Allbäck is a Swedish firm (where linseed paint for exterior use has never gone out of fashion) known for their commitment to linseed paint. They have been instrumental in researching modern understanding of the finish’s behaviour.
Brouns & Co. have a large range of their own linseed paints, and excellent technical support.
Traditionally used on masonry, lime plasterwork, woodwork and furniture (the white ‘limed’ finish beloved of the Elizabethans has the added benefit of deterring woodworm), this most breathable of paints is again simple and ancient. A loose, watery slurry of lime-putty can be used on its own for a bright, white finish (‘whitewash’), or combined with inorganic pigments for a wide variety of colours. The finish is pleasingly variable as drying times differ with the weather; substrate absorbancy; consistency of mix and applicant skill. It is a fragile coating unless other binders are added, so whitewashed houses were regularly re-painted as the finish gradually washed away in the rain.
Mike Wye’s limewash is mixed with linseed oil for improved binding.
A product made by Earthborn rather than a category, this is included as clay pigments have been used since the earliest cave paintings. Although it contains some vinyl-acetate emulsion as a binder (VAE – a plastic product common to vast numbers of conventional adhesives and paints), it has excellent breathability and the scent of wet clay as the opaque, creamy paint goes on transforms the decorating experience into something really rather pleasant. After drying, the paint is delicately matt and chalky, with a slight variation of deep shades across the surface.
Mike Wye in Devon run courses on the use of lime, make their own lime putty as well as supplying a great range of environmentally sound paints and coatings.
The Old House Store sell a variety of traditional building materials.
Ty-Mawr of Brecon stock building materials as well as a good range of paints, oils and waxes.
Traditional Paint of Hertfordshire make their own range of linseed and lime paints.
These are all suppliers and paints we have used ourselves, and we have no connection to the companies named except as satisfied customers.