Home Treatment Guidance How does Woodworm Treatment work?
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Woodworm treatment carrier

The bulk of any ready to use timber preservative is what is termed the 'carrier'. The carrier is the medium in which the active ingredient (the insecticide) is suspended and the means by which it is applied and distributed uniformally over the timber surface being treated.

Originally the carrier used in most preservatives was white spirit which had a very pungent unpleasant odour and posed a significant fire risk. Today most modern timber preservatives used by the industry use water as their carrier which means they are virtually odourless and pose no fire risk. They are usually supplied as a concentrate for dilution with water before use.


Active ingredients

The active ingredient of a modern water based woodworm treatment material is suspended as a micro emulsion in a water carrier and its penetration into the wood surface is aided by surfactants. The most common insecticide used to control woodworm is Permethrin though growth inhibitors are used by some manufacturers. The level of active ingredient is important but need only be very small. For example in its ready to use state a full strength micro emulsion insecticide preservative contains only 0.2% Permethrin. Some manufacturers have halved this level promoting an on going debate within the industry.

When Permethrin water based woodworm treatment is applied onto timber by brush or spray its micro emulsion formulation, aided by surfactants, penetrates 4 - 6mm into the surface. The carrier (water) then evaporates off leaving behind the active ingredient Permethrin, deposited in the surface of the timber where it will remain for a very long time providing long term protection.


How does it actually work?

For any surface applied insecticidal timber preservative to be effective it has to be applied onto all surfaces of a piece of timber at the prescribed application rate. For treatment to be effective the timber must be bare and not coated with paint, varnish or any other material likely to inhibit penetration of the active ingredient.

At two stages during the life cycle of woodworm it has to pass through the surface of timber; when boring in as a larva or when emerging as an adult and it is these vulnerable stages of the life cycle that are exploited. A Permethrin based woodworm treatment has both contact killing properties as well as stomach poisoning properties so it is what is termed a preventative and curative material.


Preventative capability

If eggs are laid on a treated timber surface the larvae which hatch from them will instinctively bore into the timber and the stomach poisoning properties of Permethrin will prevent any further progress. This therefore prevents a new infestation from entering treated timber and the active ingredient remains potent for a very long period of time prevent future infestations from occurring.


Curative properties

If woodworm treatment is applied onto timber which is already infested, eventually the larvae which are deeper in the timber than treatment has penetrated have to pupate and the adult insect has to emerge through the surface. Most adult woodworm do not eat the wood when exiting but they have to come into contact with the timber surface that has been treated with the woodworm treatment whereupon the active ingredient will involuntarily be absorbed and the desired effect achieved.


© Peter Macdonald  


Contact Peter: Email - info@dampdecay.co.uk - Telephone: 015242 71794