# Evaluation of Color Change and Biodeterioration Resistance of Gewang (_Crypha utan_ Lamk.) Wood
## 1 Introduction  
Log production for the Indonesian wood industry reached 47.9 million m\({}^{3}\), with 85% of production being from plantation forests in 2018 [1]. The need for timber supply in the country significantly increased by 4 million m\({}^{3}\)/year, causing a serious shortage of high-quality timber in the last four years. This requires multiple approaches, including exploration of \"new timber\" resources, particularly from endemic species. One of the endemic tree species that grow in Nusa Tenggara Province is gewang (_Crypha utan_ Lamk.) [2, 3].  
At a mature stage, gewang trunk could have 2.8 tons of biomass with an average density of 0.50 g\(\cdot\) cm\({}^{-3}\). In terms of volume, such amount of lignocellulosic material has a great potential as a source of building materials. People in East Nusa Tenggara Province have been using gewang wood as building materials for a long time. The outer part of the gewang trunk is also used for flooring to replace wooden parquet [4]. However, the inner part of the gewang trunk has significantly lower density, as well as modulus of elasticity (MOE) and modulus of rupture (MOR), compared to those of the middle and outer parts [5]. This leads to ineffective utilization of the inner part of gewang trunk as a building material. The inner part of gewang trunk is also very susceptible to biodeterioration [6]. It was reported that the damage due to biodeterioration in Indonesia, especially termite attacks, reaches approximately USD 1 billion on wood-based material in buildings [7]. It is expected that this valuewill increase in the future if non-durable timber continues to be used in the building constructions without any particular treatment to increase their overall resistance.  
One of the most effective treatments to improve the durability of wood is smoke treatment. Such treatment has long been used in the food industry to extend product shelf life, provide flavor, and change the color of the product [8]. Smoke from wood contains a large number of polycyclic aromatic hydrocarbons, which are predominantly phenols, aldehydes, ketones, organic acids, alcohols, esters, hydrocarbons, and various heterocyclic compounds [9]. [PERSON] et al. [10, 11] determined solid wood and glued-laminated lumber specimens exposed to wood smoke are more resistant to subterranean termite attack than control specimens, and two weeks exposure time to smoke increases the resistance of sengon (_Falcataria moluccana_), manii (_Maesopsis emini_) and mangium (_Acacia mangium_) also as a result of smoke treatment resistance level of the sample increased one class based on the Indonesian standard. However, longer smoking periods are required to reach the higher class (or very resistant) level of resistance. Smoke treatment with a longer period lead to color changes in sengon and mangium wood compared with untreated wood [12]. There is very little or no information on color change and biodeterioration resistance of smoked gewang wood as a function of smoke treatment.  
Therefore, the main objective of this study was to determine the color change and resistance of smoked gewang wood specimens from different parts of the trunk, longitudinally as well as transversally, to dry-wood termite and decay fungus attacks when they were exposed for three weeks to function smoke treatment. The resistance of the control and smoked treated wood specimens were also compared.