Boron timber preservative

We have considerable experience in carrying out timber conservation work using Boron in the form of Disodium octaborate normally carried in a mono-ethylene glycol.  Boron has been used for over 50 years in the timber preservative industry, in the form of inorganic borates, and is well established as an effective fungicide with insecticidal qualities.

Boron can penetrate up to 40mm into damp timber
Boron penetrating wood

Unlike most timber treatments a correctly formulated Boron timber preservative will penetrate into damp timber rapidly, and has been shown to penetrate up to 40mm into sapwood and heartwood, and will act as a preventative treatment as well as supply a rapid kill of existing fungal growths.  The Boron stays fixed in the timber for the life of the building, it can improve fire resistance of timber, and does not give of any vapour, which is liable to affect the inhabitants, including children, bats and fish.


base active ingredient in born wood preservative

Boron is a rare element, present in the earth’s crust in ubiquitous small proportions. It is never found free in nature but invariably occurs in concentrated forms as an oxide (boric oxide) in combination with oxides of other elements to form inorganic borates.


Inorganic borates have been known as cleaning agents since the days of the ancient Greek and Roman empires, and is used in the USA as Borax® which is a detergent booster and house hold cleaner and also use as food preservatives in Europe and America.

Boron has also been shown to be an essential element for plant growth, although in excess is toxic to plants, and effective herbicides have been developed to exploit this.


A preventative timber treatment usually involves the application of an insecticide and or a fungicide carried in either white spirit or water. Various chemicals are used to combine the active ingredients with the spirit or water-based carrier: in each case the active ingredients are normaly applied by spray or brush. 

These traditional preventative treatments often use Permethrin as an insecticide, or Polyphase etc, as a fungicide.  The problem with all such treatments is that they involve the release of the vapour from the carrier into the atmosphere in which you live. In addition, such treatments can only be fully effective on the surface of materials, and their penetration is generally insufficient to be useful against anything other than Common Furniture Beetle (woodworm) attack in softwoods.


An eradicative timber treatment for wood boring insects consists of applying wood preservatives to affected timbers in order to kill the larvae present in the timber or to provide a layer of “poisoned” timber which will kill woodworm larvae near the surface or when they pupate into a beetle and attempt to emerge through the treatment envelope.

An eradicative treatment for Dry Rot, in timber or masonry, consists of the removal of Dry Rot infected material and the cutting back into visually unaffected areas to ensure that microscopic strands are not present in retained components.

Traditional chemical treatments are then applied to the remaining materials as a temporary preventative, i.e. until timbers dry out. In other words, where Dry Rot is concerned, there has been no eradicative treatment. This is why standard Dry Rot specifications include severe cutting back of sound and usable material.


Using a professional wood preservative with Boron in a carrier formulation will allow you to treat and retain infected timber which a tradition chemicals cant, as they have significate problems in penetrate into damp timber, it is this ability which has saved my client’s thousand pound due to ability to actually treat dry rot.

Nigel Foster

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