**Wettability of Wood Surface Layer Examined From Chemical Change Perspective**

**Eva Annamaria Papp 1, Csilla Csiha 1, Adam Nandor Makk 2, Tamas Hofmann 2 and Levente Csoka 3,\***


Received: 17 February 2020; Accepted: 8 March 2020; Published: 10 March 2020

**Abstract:** The e ffect of artificial ageing on spruce (*Picea abies*), beech (*Fagus sylvatica* L.), birch (*Betula pendula*), and sessile oak (*Quercus petraea*) wood surfaces were investigated using qualitative (total phenolic and total soluble carbohydrate content) chemical examination methods. During ageing ( 240h), the influence of surface chemistry modifications was monitored by contact angle measurements of polar, dispersive (distilled water), and dispersive (diiodomethane) liquids. The results clearly show the relation between the ratio of main chemical components of the wood surface layer and surface wettability during artificial radiation. The identified surface chemistry modifications cause more significant change in the contact angle of polar and dispersive liquid, relative to the change of dispersive liquid contact angle. Chemical changes of the wood surface layer are due to the degradation of the main wood components (cellulose, hemicelluloses, and lignin) which can be properly monitored by total phenolic (TPC) and total soluble carbohydrate content (TSCC) measurements.

**Keywords:** wettability; phenol; carbohydrates; beech; birch; spruce; sessile oak
