Pathologies of wood
Timber, by the fact that organic material is susceptible to the attack of living beings, which cause degradation. This fact makes the widespread image of the wood is that of being very little durable material , but that view is only partly true since wood is a material impervious to oxygen in the air oxidizes the metal , and very insensitive the light that degrades plastics. That is, the wood is practically unaffected by the physical environmental agents . With respect to biotic (fungi and insect attack ) , under optimal conditions for them , can completely degrade wood, there are solutions that Classic gate applies to all doors that avoid these attacks , which together with the characteristics of timber oak doors make very durable .
Perhaps not value the hundreds of years that have kept the structures of many cathedrals , for the simple fact of having a small maintenance over time that prevented its wetting , such as the Cathedral of St. Mary of Vitoria. In the same way , the wood carvings by Veit Stoss , with five centuries old , have remained to this day intact .
It is true that wood is degraded , but should examine under what conditions does today exist intensive treatment to try to not occur and inevitably make minor maintenance so that the wood lasts hundreds of years.
To know what we face must first know , the wooden biotic destroyers are classified into two major groups: (fungi and insects)
Fungi have been specialized to feed on organic matter of dead trees , ie wood, there are two kinds :
- Fung : Feed the cellular content of the wood cells , causing a bluish color , usually not affected since the resistance does not alter cell wall responsible for the resistance of it. Being blue wood, is a sign that the wood has been or is exposed to favorable conditions for fungal growth .
- Rot fungi : They feed on the cell wall, seriously compromising its strength. Wood breaks into cubes or fibers depending if they feed on cellulose or lignin respectively.
For one or the other can live at the expense of wood is needed to produce conditions that essentially are:
- Internal wood Humidity : Below 20 % the fungus can not grow , about 60 % find the optimal conditions and above 140 % there is not enough oxygen for you to live .
- Temperature: They develop between 3 and 50 degrees , finding the optimum around 37 degrees .
Insect borers : Within Spain there are the following insects that feed on dead wood :
- Lyctidae ( Moths ) : moth larvae feed on the starch contained in the cell wall , for which practice galleries around 1mm in diameter , destroying the wood , and leaving behind a very fine sawdust . When the larva becomes an adult, out of wood to mate, then the female can the eggs from which the larvae will again. The cycle is repeated every year . No Damage, because the galleries are very small and wood waste is negligible .
- Anobiidae ( Woodworm fine ) are insects with a cycle very similar to the above , differing in feed on cellulose, galleries practiced about 2 mm in diameter leaving behind a less fine sawdust . No major damage occur , but must be taken into account .
- Cerambycidae ( Woodworm thick ) : The modus operandi is the same , the larva feeds on cellulose, but leaves holes plugged a 6mm diameter with very coarse sawdust . Damage to wood can become important if not treated early.
- Termites: are insects that can cause further damage to the wood , unlike the previous ones, the attack is produced by adult insects caste workers. They are social insects , grouped in colonies of thousands of individuals , the queen lays eggs that hatch into nymphs , which can develop into workers , soldiers or winged . These insects live in wood but in termite mounds located inside the ground, leaving the mound the night to go to the area where there is wood to feed. For this construct galleries inside the ground, without ever leaving the outside, are able to penetrate buildings, including drilling concrete, having reached the feeding of wood pulp , leaving free galleries sawdust, unlike above , termites never leave traces of their attacks , causing alarm attacks endangering entire neighborhoods simultaneously . More info on termites in http://www.expertoentermitas.org/
Knowing these fascinating ” bugs ” , and what they can do, it is imperative that all work done with wood have an appropriate treatment against them, even indoors .
Recommendations : Waterproofing treatment to maintain the internal humidity of the wood below 20% avoiding wood rot fungi and specific treatment against insect attack from time to time perform visual inspection and maintenance with a specific product .
Apart from biotic agents (fungi and insect attack ) are abiotic agents such as sunlight can degrade the wood.
Degradation by sunlight : The first effects of light are evident between the first year and seven years , depending on the degree of exposure that is wood, changing color , so if the wood darkens is clear and clarifies if the wood is dark . After 100 years of exposure degradation affects only the first few millimeters of wood and cellulose that provides protection destroyed the rest and affects more sapwood than the heartwood . This process enhances the grain and is imitated by many carpenters by applying aging techniques .
The light degradation is faster when combined with water, because it drags the decomposed cellulose surface and the rest left unprotected .
Recommendations : Avoid as far as possible direct contact with the sun , north orientations are much more favorable than the south orientations . Protecting wood from rain and spattering roofs, for example, installing a gutter .