Why, when and how to do it. A complete guide to woodworm treatments
Insights | 04 April 2019
Have you found holes in your furniture or in the rafters of your roof when you thought you would never have woodworm problems? Or have you already carried out a woodworm treatment but shortly afterwards found new holes in the wood?
Are you thinking that you have so far received bad advice and wasted your money on ineffective wormwood treatment products? I have some bad news: you may be right. However, this does not mean that the woodworm problem cannot be solved!
What you will find in this article is a detailed analysis of woodworm treatments, which will allow you to understand which may be the best solution to eliminate woodworm in your specific case.
Wood is a natural material that has its own intrinsic durability, which varies not only from species to species but also between mature wood (heartwood) and younger wood (sapwood) of the same species. Natural durability is influenced by the presence of substances called 'extractives' and conditions the damage that woodworms and termites - termed xylophagous insects - can produce. The term xylophagous refers precisely to the fact that these little animals use wood as food (from the Greek xýlon 'wood' and phagèin 'to eat').
In general, it can be said that the sapwood is the area of wood most easily subject to biotic degradation because it contains sugars, starches, amino acids and mineral salts that act as nutrients for insects (especially Lyctids).
Heartwood extractives - polyphenols, tannins, terpenoids and tropolones - on the other hand, are toxic to xylophagous organisms, but it should be remembered that the type of substances and the quantity contained in the wood vary from species to species. There are also wood species defined as having 'undifferentiated heartwood' because in them the heartwood has the same durability as the sapwood: these include fir, poplar and beech.
Natural durability of some wood species used in Italy (NR = not resistant, MR = moderately resistant, R = resistant, * = heartwood is also attacked)
It must be borne in mind that the quality of wood and people's lifestyles have changed a great deal in recent decades. This has also led to a change in the habits of the insects themselves, which today can sometimes be found in wood materials (e.g. plywood or veneer) that were previously very unattractive to woodworms.
As can be seen in the table above, there are no wood species that can resist all xylophagous insects.
Carrying out a preservative treatment therefore means increasing the durability of the wooden element, so as to ensure greater protection and resistance to biological attack. The treatment can be carried out to eliminate woodworms or termites that are already attacking the wood (in this case we speak of curative treatment) or to prevent new settlements (preventive treatment).
Microwave woodworm treatment is based on the absorption of electromagnetic energy by wood, whose chemical structure is characterised by the presence of water molecules.
The effectiveness of microwave treatment depends essentially on two factors:
• wood moisture;
• wood thickness.
What is the mechanism behind the treatment? Water molecules are polar which means that they are able to orient themselves if they are in the presence of an electric field (this is the so-called polarisation phenomenon). Microwaves are able to exert forces on the electrical charges of water molecules, causing them to vibrate. By vibrating, the molecules rub against each other and heat up through friction.
Water is therefore of fundamental importance in microwave woodworm treatment: the greater is the amount of water in the wood, the more it heats up (the same principle is used when cooking food in a microwave oven!).
However, it must be remembered that the absorption of electromagnetic energy decreases as the depth of the material increases, and the maximum depth of treatment decreases as the moisture content increases. Usually, mortality of larvae, eggs and pupae can be achieved in wood several centimetres thick.
When using this technique, attention must be paid to any metal parts that may be present in the material to be treated (e.g. nails, screws, hinges). Metal objects are very good conductors of electricity: electric currents that strike a conductor can cause a rise in temperature, which can lead to localised overheating or even burning.
Generally, for microwave treatment, a device called a 'magnetron' is used, which generates energy with a frequency of 2450 MHz, the most useful for causing interactions with water and corresponding to a wavelength of 12.25 cm. The heating occurs rapidly and must be maintained for several minutes to ensure 100% mortality of the larvae. Usually, the temperature of the insects is raised to around 55 °C (smaller larvae can also die at around 52-53 °C), while the wood does not exceed 45 °C. This temperature difference occurs due to the fact that woodworms and wood have different thermal and electrical properties.
It is possible to carry out a local treatment, using an applicator, or a general treatment in a reverberation chamber.
At the risk of being repetitive, we would like to remind you that it is important to read the label of the wormwood treatment product you want to buy. Why is this concept so important to us? The answer is simple. The label contains all the information about the product's characteristics, its performance, how to use it, its content and specific hazards. A consumer who informs himself is an informed consumer, who knows what he has bought and how he should use the product.
How can you tell if the wormwood treatment product you receive is a product that meets the standards and is therefore legally placed on the market?
Annex V of Regulation (EU) No 528/2012 lists the types of biocidal products by group and product type. Product-type 8 (or PT 8) identifies wood preservatives, i.e. “products used for the preservation of wood, from and including the saw-mill stage, or wood products by the control of wood-destroying or wood-disfiguring organisms, including insects”.
In 2014, Commission Implementing Regulation No. 1090 was issued approving the use of permethrin as an active substance in biocidal products of types 8 (wood preservatives) and 18 (insecticides, acaricides and products intended for the control of other arthropods).
Woodworm treatment products that contain only permethrin must therefore follow the guidance given in the regulation on the 'Classification, packaging and labelling of biocidal products' (Art. 69).
Let us look together at what information a permethrin-based woodworm treatment product must mandatorily display on the label (but which it would not be bad to also find in the technical data sheet):
1. Authorisation holders shall ensure that biocidal products are classified, packaged and labelled in accordance with the approved summary of biocidal product characteristics, in particular the hazard statements and the precautionary statements, as referred to in point (i) of Article 22(2), and with Directive 1999/45/EC and, where applicable, Regulation (EC) No 1272/2008. In addition, products which may be mistaken for food, including drink, or feed shall be packaged to minimise the likelihood of such a mistake being made. If they are available to the general public, they shall contain components to discourage their consumption and, in particular, shall not be attractive to children.
2. In addition to compliance with paragraph 1, authorisation holders shall ensure that labels are not misleading in respect of the risks from the product to human health, animal health or the environment or its efficacy and, in any case, do not mention the indications ‘low-risk biocidal product’, ‘non-toxic’, ‘harmless’, ‘natural’, ‘environmentally friendly’, ‘animal friendly’ or similar indications. In addition, the label must show clearly and indelibly the following information:
(a) the identity of each active substance and its concentration in metric units;
(b) the nanomaterials contained in the product, if any, and any specific related risks, and the word 'nano' in brackets after each reference to nanomaterials;
(c) the authorisation number allocated to the biocidal product by the competent authority or the Commission;
(d) the name and address of the authorisation holder;
(e) the type of formulation;
(f) the uses for which the product is authorised;
(g) the manner of use, frequency of application and dose, expressed in metric units, in a manner that is meaningful and comprehensible to the user, for each type of intended use under the terms of the authorisation;
(h) details of probable direct or indirect adverse reactions and any instructions for first aid;
(i) if an instruction leaflet is enclosed, the words 'Read the enclosed instructions before use' and, where appropriate, warnings for vulnerable groups;
(j) instructions for the safe disposal of the biocidal product and its packaging, including, where applicable, any prohibition on the reuse of packaging;
(k) the batch number of the formulation or designation and the expiry date under normal storage conditions;
(l) if applicable, the period of time needed for the biocidal effect, the interval to be observed between applications of the biocidal product or between application and the next use of the product treated, or the next access by man or animals to the area where the biocidal product has been used, including particulars concerning decontamination means and measures and duration of necessary ventilation of treated areas; particulars for the specific cleaning of equipment; particulars concerning precautions to be taken during use and transport
(m) where applicable, the categories of users to which the use of the biocidal product is restricted;
(n) where applicable, information on any specific hazards to the environment, with particular regard to the protection of non-target organisms and provisions to avoid water contamination;
(o) for biocidal products containing micro-organisms, the labelling requirements of Directive 2000/54/EC.
As you have just read, in paragraph 2 of Art. 69, the label cannot bear the "wording 'low-risk biocide', 'non-toxic', 'harmless', 'natural', 'environmentally friendly', 'animal friendly' or similar wording" because to do so is to create misleading communication. Woodworm treatment products are dangerous precisely because of their specific biocidal action: there can therefore be no such thing as a non-toxic woodworm treatment product.
The regulation also requires that the authorisation number assigned to the biocidal product be shown on the label.
Are you now convinced that it is important to read the label of the woodworm tratment product?
If you don't have time to go to the hardware store or the paint shop to evaluate the various products, you can also do some research in front of the computer: you can find the technical data sheets on the Internet, which usually contain all the information you need to understand whether the product is legal and can solve your problem. To avoid surprises once you have purchased the woodworm treatment product, be wary of those who show very little information on their website, do not provide the product's technical data sheet and do not mention European Regulation No. 528/2012.
Microwave, hot air or modified and controlled atmosphere woodworm treatments are not subject to biocide legislation because they do not use biocidal active ingredients. This does not detract from the fact that these methods must still comply with current regulations on safety for humans and the environment.
We hope with this article we have clarified your ideas on woodworm treatments. If you have any other questions or curiosity, please do not hesitate to write to us!
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