Açık hava koşullarının ağaç malzemenin kimyasal yapısında meydana geterdiği değişimler ve alınacak önlemler

Isık, rutubet, rüzgar ve sıcaklık gibi çesitli etmenler karsısında ağaç malzeme yüzeyinde çesitli bozunmalar meydana gelir. Renk değisimi ile baslayan bozunma fiziksel, kimyasal ve anatomik yapıda da etkisini gösterir. Özellikle UV ısını etkisiyle büyük oranda degrade olan lignin yağmur suları ile yıkanarak odundan uzaklasır. Bu durum mikroskobik yapıda öncelikle orta lamelin bozunmasına neden olur. Ayrıca, kenarlı geçitlerde çatlaklar olusur ve iki hücre arasındaki hücre çeperinde ayrılmalar görülür. Odun yüzeyinde çatlak olusumu ve yüzey pürüzlüğü gerçeklesir. Ağaç malzeme, açık hava etkisine karsı yaygın olarak boya ve verniklerle korunmaktadır. Verniklere oranla boyalar daha iyi sonuç vermektedir. Ayrıca, suda çözünen tuzları içeren emprenye maddeleri de kullanılmaktadır.

Anahtar Kelimeler:

vernik, ultraviyole ışıması, odun koruyucular, odun kimyası, ahşap boyama, odun koruma, açık hava koşulları

Influences of weathering on chemical structure of wood and protection treatments

Degradations could be occurred on the wood surfaces by the presence of light, moisture, wind and temperature. Weathering begins with color changes and further in physical, chemical and anatomical structure on wood surfaces. Specially, lignin is destroyed by UV light and then leached out from the wood by rain. This effects the microstructure and likewise middle lamella begins to be destroyed .Also, cracks can be seen in the border pits and the cell walls between two cells begin to separate. During weathering rough and cracks can be seen on the surface of wood. Painting, coating or preservatives are useful techniques to protect wood surfaces against weathering. Painting is more effective then coating. Also water-repellents can be used for various purposes.

Keywords:

varnishes, ultraviolet radiation, wood preservatives, wood chemistry, paintings on wood, wood preservation, weathering,

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