MAINTENANCE INTERVAL – Wooden surfaces that are exposed to sun, wind and rain become leached and appear grey and weathered, and splits appear. Tarred surfaces also age in this manner. It is time to renew the tar treatment when the above processes take place. The normal maintenance interval for exposed surfaces that face south or west is 5 years, while 10 years may be sufficient for surfaces that face north or east. Longer maintenance periods may be used for surfaces in protected locations.

The resin content of the pine tar replaces the natural resin of the wood. Examine the quality of the wood and whether any damage is present, before applying tar. One useful technique is to dip new wood into hot pine tar before mounting it.


CLEANING – The surface is to be cleaned by brushing. Any flaking surfaces or surfaces with thick coverings must be scraped. A high-pressure cleaner may be used, but requires thorough subsequent drying of the wood before further treatment.

Tools, brushes and other fittings, etc., are to be cleaned with denatured alcohol. Pine tar is not soluble in mineral turpentine or similar solvents. Pine tar on the skin can be removed with soap and warm water.


GENERAL – It is preferable that the work be carried out during the summer. The surface to be treated must be dry. A high temperature, a sunny day for example, makes the work easier and gives better results. Warm the tar to a constant temperature (not greater than 70 °C), to get a better result. Stockholm Tar gives better surface protection, dries more rapidly and gives a surface that resists wear better than kiln-burned tar. An old method for determining the quality of pine tar is to see how light it is, the lighter the better.

The drying time may range from approximately 24 hours to several weeks or even months, depending on the tar quality, the thickness of the tar layer, and external factors such as temperature, amount of sun, wind and absorption.

Tar should not normally be thinned. An exception may be made for the first coat, in which case it can be thinned with mineral spirit or vegetable-based turpentine, turpentine oil. A few percent of mineral spirit should always be added in order to give better solubility.


APPLYING TAR – Two coats are normally required to achieve a resistant surface. Application by brush gives the best result. A curved-handle round tarbrush should be used, with relatively long and stiff natural fibres. A high-pressure spray can be used, but the surface should then be brushed over afterwards.

It is always an advantage to work with warm pine tar. Remember that tar that cools while you are working will lead to you applying gradually more of the viscous tar, and this may give clear differences in tone and thickness when application of a new bucket of warmer pine tar starts. It is sometimes possible to see on the finished surface where you were working when clouds covered the sun.

The first coat is normally totally absorbed into the wood. If the wood is so saturated that the first coat remains after several days as a surface film, it may be sufficient to apply only one coat. Test a small patch before beginning work.

There may be differences in the colour and viscosity of tar from one package to the next. Try to continuously mix the tar while working, to prevent large differences on one surface. Shake the containers while working. Stir thoroughly while the tar is being warmed and used.


COVERAGE – The coverage can be roughly estimated as follows: a first coat on a dry, absorbent surface, i.e. dry newly sawn wood or old leached wood, will cover 2–4 m2 per litre, the second coat 4-6 m2 per litre. There is a wide variation in consumption, depending on the quality of the tar, the properties of the surface (sawn or planed), weather conditions, working procedures, etc.