Why Important
What to look for
When to look
How to fix
There are many different types of coatings available for applying to wood. These include:
Oil based gloss paints
These consist of a primer, an undercoat and a gloss top coat and use white spirits as a brush cleaner.
Water-borne gloss paints
These are similar to the oil based paints above but use water as a brush cleaner and can have better flexibility over time. They also do not yellow and although they are not so glossy initially, they do not lose their gloss like oil paints. There are several different types so follow the manufacturer’s instructions carefully.
Lead Paint
When the Birkenhead Heritage Georgian Quarter was being built and painted, most exterior paints contained white lead as the main pigment, mixed with linseed oils. This gave a very flexible paint which dried to a low sheen finish with an off-white colour.
However white lead paints are harmful to health if they are taken into the body either by inhaling or ingesting their dust.
Since the 1960s, white lead has been replaced by other pigments which are not harmful and give a brilliant white colour. Paints containing white lead can now only be used on Grade 1 Listed buildings.
Wood stains
These can be either oil based or water borne and either semi-transparent or opaque depending on how much they hide the wood grain. They generally do not give such a thick coat as the paints and thus are less likely to crack if the wood flexes. Wood stains normally have a low gloss finish. Many stains also claim to be ‘Microporous’. This means that they allow water vapour to pass through them without breaking the skin, which can allow any unseasoned wood to dry out more easily. [ what? check original text] in the putty being absorbed into the wood, leading to the putty drying out and cracking.
Varnishes
These also can be either oil or water based. Those for exterior use are generally labelled as “Yacht”,”Spar” or “Front Door “ varnish and may say that they contain UV (Ultra-violet) absorbers. Varnish will not last as long outside as paint and so will need more frequent maintenance, unless used in areas protected from direct sunlight.
Timber Oils
These are used on naturally oily woods such as teak to help replace their oils. They must be applied to bare wood to be effective. They can be rather impractical and hard to maintain in exposed locations such as Hamilton Square terraced buildings as they are attacked by sunlight, and are also slightly soft and will retain dirt. However they are frequently seen in more protected locations such as courtyards and darker passages.