What is tanalised timber?
Tanalised Timber is any timber that has gone through a treatment process to provides protection from wood decay and insect attack. This increases the longevity of the timber. The process involves untreated timber going into a vacuum chamber which gets flooded with a chemical product called ‘Tanalith E’ which the timber then absorbs.
Tanalith wood preservative has been around for many years, which has given it the very important test of time. It is widely believed to be the very best protection for timber.
Be careful buying timber that is just described as ‘treated’ timber, as this can be timber that has just been dipped in and out of a tank of treatment, rather than put through a vacuum tanalith process. The dipping treatment doesn’t give the same level of treatment, resulting in a shorter service life and a poorer quality finish.
Do I still need to treat tanalised timber?
No. You don’t need to add further treatment to tanalised timber as it has already had the very best treatment to protect it against the elements.
If you do decide to add extra treatment yourself to extend the lifespan further, it is important to make sure it is done at the correct time. Tanalised timber can have some Tanalith residue left on the timber for some time, meaning any other product you apply to it will not adhere to the timber properly. You should wait at least 2-3 months to add extra treatment. A good indication of the timber being dry enough to treat is when it turns from green to yellow/golden brown.
Can I still paint tanalised timber?
Yes. Painted wood can add a lot to your garden whilst also adding an extra layer of protection. Although as explained above, just be careful not to do it too early.
Also, remember that once you paint it once, you will most probably find it needs repainting every now and again to keep it looking good. The better the quality of paint you buy, the less frequent this will need to be done.
Some tanalised timber looks green. Will it stay green?
No, the green colour doesn’t stay around for long.
The green colour comes from the Tanalith treatment that is sucked into the timber. Once exposed to weather conditions and UV light from the sun, it will start changing colour. During the first few months, it will change from green to a yellow/golden brown colour. Eventually, it will then turn to a silver grey colour. This change in colour isn’t the timber rotting, it is just the natural weathering process.
Tanalised timber can sometimes be different shades of green. This due to different species of wood making the treatment appear to be a different colours, and also a matter of how long since the timber came out of the treatment tank and been exposed to weather conditions. These different shades will soon catch up with each other after a few months of being exposed to the same weather conditions.