Steaming Deresination And Anti-dicoloration Drying Of Pinus Massoniana Lamb

Our country is relatively short of forest, wood supply is not enough, and this tendency intensified day by day. Till year 2003, the balance between supply and requirement reached 38 million cubic meters, one of the efficient solutions is to explore the man planted tree species. In our country Pinus massoniana is widely distributed æš—æ·¡ and has a large amount of storage, in the meanwhile its growth period is short and its quality is good, so it is a very potential man planted tree species. Pinus massoniana Lamb is light colored with beautiful texture, its foreground to use in furniture manufacture is full of hope. According to our country record about pine wood furniture in west Europe, North America, Singapore and Japanese etc., pine wood has a wide area of market. But Pinus massoniana Lamb is easy to get brown during drying and resin overflow during manufacture and use, these affects the beauty and coating property, so it is still not widely used as decorating wood. Wood color is one of the main factors that measuring wood quality, discoloration damaged the beauty of wood vein and hue, directly and badly damaged wood and its products appearance quality, it is a major factor that restrict wood selling and manufacture, in our country plywood, furniture, flooring are all have regulation on wood color.Based on the related material both home and abroad, the paper analysis the factors that caused the discoloration of Pinus massoniana Lamb during drying, and designs a serials of drying schedules. First, steaming deresination, confirm the optical treating time, in the meanwhile relieve the discoloration and drying time later on. Secondly, through experiment and analyzing a serials of drying schedules, investigate the influence rale of some factors such drying temperature, drying time, medium relative humidity and wood moisture content. By measuring every color parameters after drying, analyzes the influence rule of drying technical parameters to discoloration of Pinus massoniana Lamb such as lightness, hue, chrome and total color difference. Chooses proper drying schedule, effectively controls the discoloration degree and depth, shorts the drying time and guarantees the drying quality. Finally, by pre-steaming and then proper drying, chose an optimum pre-steaming time and drying schedule, which madePinus massoniana Lamb remains nature and fresh color and deresinated effectively, in the meanwhile, guarantee drying quality and short drying time. The result shows that:1) Pre-steaming can made Pinus massoniana Lamb deresinated. As steaming time continued, wood resin content decreased gradually. During the initial steaming phase, deresination rate increases quickly, as time goes by, the acceleration rate slows down. During the initial steaming phase, Pinus massoniana Lamb remain fresh and nature color, when steaming time exceed 5 hours, the surface gets darker and darker.2) When drying temperature and drying medium relative humidity enhanced and drying process continues, the lightness of Pinus massoniana Lamb decreases gradually, hue and chrome increases, and total color difference increases too.3) After drying, the color parameters changed more or less in different depth, among which the lmm depth is the most intense, the second intense layer is the surface, and the 2mm depth and finally the 3mm depth.4) The discoloration during drying begins when the wood moisture content is quite high (much higher than fiber saturation point), as moisture content decreasing, each color parameter increases gradually, and reaches the maximum in the end of drying, discoloration is an accumulated process. When other drying parameters are same, the longer the drying time, the more changes of each color parameter.5) Generally speaking, drying temperature has more affection on hue, and relative humidity has more affection on chrome.6) After per-steaming, every color parameter of Pinus massoniana Lamb gets better more or less, among which chrome is most obvious, and lightness, hue, total color difference are all get better than the same drying schedule without per- steaming. Wood drying quality improves and drying time shortened after pre-steaming. __ .7) Over all, considering color, drying quality and drying time, chose low-medium drying schedule with pre-steaming for 3 hours. After drying, wood color remain nature and fresh, drying quality is good and drying time is short. ,...