Responding to an article about making home made wood preservative, Michael Dutton, Managing Director Company Secretary, Designer and Log Smith of the Tsarina Imperial Dacha Co Ltd of Scotland, has provided invaluable information as to the preservation of timers. We would like to thank Michael for the tremendous information that he has provided. Please visit Michael’s website as he provides a wealth of information and their services regarding handcrafted custom log structures.
Michael has also made himself available via Skype with the user name RasputinScotland.
I have a log building business in Scotland, UK and have been reading your articles on the use of Borates. We only use borates for the preservation of our logs. All logs are pre-treated with a 20% (10% Boric Acid and 10% Borax) by weight ratio with water onto our freshly processed timber whilst the moisture content is still very high. The water acts as the carrier for the borates which are then transported deep into the timber. One added benefit of the use of the borates is that they also act as a flame retardant.
Once we get to the jointing stage of our logs, usually after several weeks of processing the logs (we machine round our logs) we then carry out a sealing process which can also be used on dried timber. This involves a mixture of cold pressed linseed oil and gum turpentine (the real stuff, not the petroleum imitation turpentine). We add a 2% (1% Borax and 1% Boric Acid) by weight ratio mix of the borates and apply to the timber.
It takes around 24 to 48 hours to dry but gives a matt gloss finish and moisturises the timber. This mixture also helps to reduce checking of the logs whilst also carrying out its other functions as an insecticide, anti fungal and flame retardant. The oil’s main funtion is to act as the carrier for the borates to deliver them into the dry timber, and when the oil reaches a moist arear of the timber the borates are then tranferred over to the water to continue the transport process. This method is one of the most efficient of all methods of timber preservation and best of all it is non-toxic, environmentally friendly and uses totally natural raw materials.
Retreatment is normally required after 10 to 12 years, although intermittent touch up is also a good thing. Points to note when calculating weights of the liquids involved is that the weights will vary depending on the liquid and their specific gravity. To help i have listed them as follows using water as the reference weight;
1 Liter water = 1 kilogram
1 Liter Linseed Oil = 0.93 kilogram
1 Liter Gum Turpentine = 0.87 kilogramMixing is then just a simple matter of maths
Remember never to store your raw linseed oil in sunlight otherwise it will become stand oil which is thicker and does not carry the borates as effectivley as cold pressed linseed oil. Linseed oil also darkens over time.
Tung Oil rather than linseed oil in the same mixtures can also be used as has been traditionally used by the Chinese for centuries in timber preservation, however one has to be careful as it is made from nuts, and should you have a visitor who suffers from nut allergies you could inadvertantly activate their allergy. As the oil is also a water barrier, your logs are protected from the rain, coupled with the borates you have a fully protected log that with care and maintenance should help keep your log home preserved for generations.
I hope this information is useful to you, and should anyone wish to contact me i can be reached on skype with the user name of rasputinscotland.
Regards
Michael Dutton
If you are planning to build or perhaps restore a log or timber structure in the UK Please contact Michael.
