Traditional, Ecological and Conventional Paints

When you want to decorate your period house, you probably visit your local DIY store, hardware store or builders merchant to buy your paints, unaware of the impact they will have on your home. Most outlets stock the popular ranges of conventional paints, including 'heritage' colour ranges but few sell ecological or pure traditional paints. They, like many homeowners are still unaware of the importance of using these paints on period properties.

Paints are usually considered purely decorative and of little consequence to a building. However, the application of a wrong coating can cause decay in a building, sometimes damaging it irreversibly. Even the beneficial effects of applying lime based mortars, renders and plasters can be completely negated by an unsuitable 'top coat'.

Differences

What are the differences between traditional, ecological and conventional paints?

In a nutshell, traditional paints are made to historic recipes, using the same ingredients and techniques. Ecological paints are derived from traditional recipes but have replaced the more environmentally unfriendly ingredients wherever possible. Conventional paints are based on modern ingredients, many derived from the petro-chemical industry. Here are some key differences in their performance:

Breathability

Old buildings need to 'breathe' and therefore all materials used on them also need high degrees of breathability. Applying a non-breathing coating causes the building to sweat, resulting in condensation and damp problems. The vast majority of modern paints are based on plastic binders derived from the petroleum industry, which effectively produce a plastic coat over the applied surface. They often have trouble adhering to the surfaces of an old house and can be seen to peel away or bubble. This is usually a combination of impermeability causing trapped moisture underneath, plus non-adherence.

Traditional and ecological paints use natural binders and most water-based products produce a breathing skin. This allows vapour from living areas to pass through the paint into the building structure. The breathability of individual paints does vary quite considerably and you should ask your supplier for further information.

Health

When you first apply paint, solvents and moisture permeate for some time into the living area. Most synthetic materials found in many modern paints secrete toxic substances, which can cause allergic reactions and other health problems.

Traditional paints vary quite considerably in the amount of toxic substances they contain. Historically many incorporated ingredients like lead and natural gum turpentine, which are now known to be very harmful. Water based paints are generally more healthy.

True ecological paints contain little or no toxic substances. Ask your supplier for a list of ingredients.

Colour

Ecological and traditional paints contain natural pigments, which incorporate a small spectrum of colours, giving a more vibrant overall appearance. The synthetic colours used in many modern paints contain no such spectrum, giving a more monotonous finish.

Smell

Traditional and ecological paints usually smell more pleasant than their modern equivalents and are less likely to cause the 'decorator's headache' syndrome.

The Choice

Listed below are the most common paints recommended for decorating your period house. These are available from specialist suppliers and come in a wide range of colours.

Traditional Paints

Water Based Paints

Lime wash	Limewash is, at its most basic, lime putty mixed with water, with pigments for colouring. For greater durability, it is often mixed with tallow or casein or linseed oil. It is the most versatile and ancient coating for internal and external use and is especially recommended as an effective and breathable external coating for historic buildings. Lime wash cannot be applied on top of other paints; the surface must be porous.
Distemper	This is manufactured from a combination of natural materials to give a smooth, easily applied finish. The ingredients include whiting (crushed chalk), size (gelatin) such as rabbit skin glue or synthetic glue, water and pigments. Distemper is the forefather of modern synthetic emulsions. There are several types available - breathability varies.
Pigment Wash	Originally this was just pure pigments mixed with water. 'Sizes' (natural glues) were later added to make the 'wash' more durable. It gives a very strong pure matt colour.
Claypaint	Claypaint is made with clay and plant material, and colour is added with minerals. It is available in a wide variety of colours.

Oil Based Paints

Natural Oil Paints

These are based on natural oils, white lead, resins and diluents (eg. linseed oil and mineral pigments), turpentine and thinners, as well as driers, producing a durable result in a variety of sheens. They provided a more flexible and therefore long lasting coat than their modern acrylic equivalents. The pigments were various earths and minerals ground in oil. They took a while to dry and the gloss finish went dull in time. The linseed oil caused yellowing.

Ecological Paints

Casein Paints	Casein paint is also called 'milk paint' as it is made from curds from soured milk which are then mixed with soda, ammonia or lime putty. Casein usually comes as a powder; you mix it with milk and can be used on walls or furniture. The finish is chalky. These paints are based entirely on non-harmful natural materials. They are highly breathable.
Emulsions	Similar to modern emulsions but without the harmful VOCs (volatile organic compounds). Fairly breathable - check with your supplier.
Natural Oil Paints	These paints are based on natural oils, resins and diluents, producing a durable result in a variety of sheens.

Managing Synthetic Paints

What do I do if I already have synthetic paints on my house?

Most modern paints don't breathe enough to allow your period house to function correctly, and therefore you should consider removing them. However, try not to remove the traditional coatings underneath. Although this sounds difficult, with the correct 'stripper' this shouldn't be too much of a problem - many suitable liquid and poultice 'paint strippers' are available; ask your traditional/ecological paint supplier for advice.

It is true that some traditional and ecological paints aren't as easy to use as their modern equivalents. Some need to be mixed up; others need several coats to achieve a good finish. If you have the patience however they can be more fun.

Conclusion

There is a tendency to think that modern is best. This isn't always the case, especially where historic buildings are concerned. By understanding how our period house functions we can repair and decorate it using materials which will help it to perform as it was originally intended and prolong its life and beauty for centuries to come.

Don't assume that traditional means boring. Contrary to popular belief strong colours were preferred through much of history, as the spectrum of colours available in traditional paints illustrates. Give traditional or ecological paints a go and enjoy living with the results.