ویژگی‌های ممتازِ چوب‌های مورد استفاده در هنر چوتاشی (ظروف چوبی سنتی در شمال ایران)

ﻫﻨﺮ«ﭼﻮﺗﺎﺷﯽ» ﯾﺎ «ﻻکﺗﺮاﺷﯽ»، ﺳﺎﺧﺖ ﺧﻼﻗﺎﻧﻪ و ذﻫﻨﯽ ﺣﺠﻢﻫﺎی ﭼﻮﺑﯽ ﺳﻨﺘﯽ در ﻗﺎﻟﺐ ﻇﺮوف، اﺑﺰار ﮐﺎر و ﻋﻨﺎﺻﺮ و آراﯾﻪﻫﺎی ﻣﻌﻤﺎری ﺑﻮﻣﯽ ﺑﺎ اﺳﺘﻔﺎده از ﭼﻮبﻫﺎی ﺟﻨﮕﻠﯽ در ﻣﻨﺎﻃﻖ ﺷﻤﺎل اﯾﺮان – ﺑﻪوﯾﮋه اﺳﺘﺎن ﻣﺎزﻧﺪران - اﺳﺖ ﮐﻪ ﻗﺪﻣﺘﯽ دﯾﺮﯾﻨﻪ دارد. ﻫﺪف اﯾﻦ ﭘﮋوﻫﺶ، ﺷﻨﺎﺳﺎﯾﯽ ﮔﻮﻧﻪﻫﺎی ﭼﻮﺑﯽ دارای ﮐﺎرﺑﺮد در ﭼﻮﺗﺎﺷﯽ و ﺑﺮرﺳﯽ وﯾﮋﮔﯽﻫﺎی ﻣﻤﺘﺎز آﻧﺎﺗﻮﻣﯽ و ﺗﮑﻨﻮﻟﻮژی (ﻓﯿﺰﯾﮑﯽ و ﻣﮑﺎﻧﯿﮑﯽ) آﻧﻬﺎﺳﺖ. ﺑﻪ اﯾﻦ ﻣﻨﻈﻮر ﭼﻮبﻫﺎی ﺧﺎم ﯾﺎ ﻧﯿﻤﻪﮐﺎر ﺑﺎ اﺑﻌﺎد و ﺷﮑﻞﻫﺎی ﻣﺨﺘﻠﻒ از ﮐﺎرﮔﺎهﻫﺎی اﺳﺘﺎدﮐﺎران ﭼﻮﺗﺎﺷﯽ ﮔﺮدآوری ﺷﺪ. ﻧﻈﺮ اﺳﺘﺎدان در ﻣﻮرد ﻋﻠﺖ ﺗﺮﺟﯿﺢ اﯾﻦ ﭼﻮبﻫﺎ و وﯾﮋﮔﯽﻫﺎی ﺑﺮﺗﺮ آﻧﻬﺎ ﻧﯿﺰ ﺛﺒﺖ ﺷﺪ. رﻃﻮﺑﺖ، ﺟﺮم وﯾﮋه، ﻫﻢﮐﺸﯿﺪﮔﯽ و واﮐﺸﯿﺪﮔﯽ ﺣﺠﻤﯽ و ﭼﻨﺪ وﯾﮋﮔﯽ ﻣﮑﺎﻧﯿﮑﯽ در ﻫﻔﺖ ﻧﻮع ﭼﻮب ﺑﺮﺗﺮ ﻣﻌﺮﻓﯽﺷﺪه (رﯾﺸﻪ و ﺗﻨﮥ اﻓﺮا، ﺗﻠﮑﺎ، ﻣﻠﺞ، ﺷﻤﺸﺎد، ﺳﺮﺧﺪار و ﮔﺮدو) اﻧﺪازهﮔﯿﺮی ﺷﺪ. ﺑﺮای ﻓﻬﻢ ﺑﯿﺸﺘﺮ ﻋﻠﺖ ﻣﻄﻠﻮب ﯾﺎ ﻧﺎﻣﻄﻠﻮب ﺑﻮدن ﺑﺮﺧﯽ ﭼﻮبﻫﺎ، ﺑﺎﻓﺖ ﭼﻮﺑﯽ آﻧﻬﺎ زﯾﺮ ﻣﯿﮑﺮوﺳﮑﻮپ ﯾﺎ اﺳﺘﺮﯾﻮﻣﯿﮑﺮوﺳﮑﻮپ ﺑﺮرﺳﯽ ﺷﺪ. ﺑﺮاﺳﺎس ﺟﻤﻊﺑﻨﺪی ﻧﻈﺮ اﺳﺘﺎدﮐﺎران ﺑﺎ ﭘﮋوﻫﺶﻫﺎی ﻣﯿﺪاﻧﯽ، ﭼﻮب رﯾﺸﮥ اﻓﺮا و ﭼﻮب ﺳﺎﻗﮥ زﯾﺮ ﭘﻮﺳﺖ در درﺧﺘﺎن ﻗﻄﻮر ﭘﻮﺷﯿﺪه ﺑﺎ ﮐﺎﺷﻢ (ﺧﺰه)، ﺑﺮای ﺳﺎﺧﺖ ﻇﺮوف ﻣﻨﺎﺳﺐﺗﺮﻧﺪ. آزﻣﻮنﻫﺎی ﻣﮑﺎﻧﯿﮑﯽ ﻧﺸﺎن دادﻧﺪ ﮐﻪ ﻣﻘﺎوﻣﺖ ﺑﺮﺷﯽ ﻋﻤﻮد ﺑﺮ اﻟﯿﺎف در ﻣﻠﺞ، ﻣﻘﺎوﻣﺖ ﺑﻪ ﺷﮑﺎفﺧﻮری در ﺗﻨﮥ اﻓﺮا و ﮔﺮدو، ﭼﻘﺮﻣﮕﯽ در ﺗﻨﮥ اﻓﺮا و ﺷﻤﺸﺎد و ﺳﺨﺘﯽ در ﺳﺮﺧﺪار دارای ﺑﯿﺸﺘﺮﯾﻦ ﻣﻘﺎدﯾﺮﻧﺪ. ﻫﻤﭽﻨﯿﻦ ﺷﻤﺸﺎد ﺑﯿﺸﺘﺮﯾﻦ وزن ﻣﺨﺼﻮص و ﺳﺮﺧﺪار ﮐﻤﺘﺮﯾﻦ ﻫﻢﮐﺸﯿﺪﮔﯽ را دارﻧﺪ. ﺑﺮرﺳﯽﻫﺎی ﻣﯿﮑﺮوﺳﮑﻮﭘﯽ ﻧﺸﺎندﻫﻨﺪة ﻫﻤﮕﻨﯽ و ﺗﺨﻠﺨﻞ ﺑﯿﺸﺘﺮ ﭼﻮب رﯾﺸﻪ و در ﻋﯿﻦﺣﺎل، درﻫﻢﺗﺎری ﺑﯿﺸﺘﺮ در اﯾﻦ ﭼﻮب اﺳﺖ. ﻫﻤﭽﻨﯿﻦ ﭘﺪﯾﺪة «آﻫَﻨَﮏ» در ﺳﺮﺧﺪار ﮐﻪ از ﻧﻈﺮ اﺳﺘﺎدﮐﺎران ﮐﺎﻫﺶ ﺷﺪﯾﺪ ﮐﯿﻔﯿﺖ آن ﻣﯽﺷﻮد، در واﻗﻊ ﺗﺠﻤﻊ ﻣﻮاد رﺳﻮﺑﯽ در ﭼﻨﺪ ردﯾﻒ ﺗﺮاﮐﺌﯿﺪ اﺳﺖ. در ﭘﺎﯾﺎن، ارﺗﺒﺎط ﺑﯿﻦ وﯾﮋﮔﯽﻫﺎی آﻧﺎﺗﻮﻣﯽ، ﻓﯿﺰﯾﮑﯽ و ﻣﮑﺎﻧﯿﮑﯽ ﭼﻮبﻫﺎ و ﻧﻈﺮ اﺳﺘﺎدﮐﺎران ﺑﺮرﺳﯽ و وﯾﮋﮔﯽﻫﺎی ﺑﺮﺗﺮ ﭼﻮبﻫﺎی ﻣﻨﺘﺨﺐ ﺗﺄﯾﯿﺪ ﺷﺪ.

superior properties of timbers used in the art of chutashi (traditional wooden kitchen utensils in the north of iran)

the art of chutashi or lucktarashi is the manufacture of traditional wooden boxes and containers using forest trees in mazandaran province, which has a long history. the purpose of this research was to identify the wooden species used in chutashi and to investigate their distinctive features and technological (physical, mechanical) excellence. hence, rough or semifinished wood specimens were collected with different dimensions and shapes from local workshops. the handicraftsmen’s reason for preferring these woods and their presumed superior characteristics were also recorded. the moisture content, density, shrinkage, and the swelling of the wood as well as mechanical properties including shear strength perpendicular to grain, cleavage strength, side hardness, and charpy impact strength (toughness) were measured on seven kinds of selected specimens (maple root, maple trunk, boissier pear, wych elm, boxwood, yew, and walnut). to further investigate the reason behind the desirability or undesirability of certain woods, their xylem was examined under a microscope and/or a stereomicroscope. summarizing the views of the craftsmen showed that they prefer the root wood of maple and closetobark lumbers of mature, thick trees. moreover, that part of a tree trunk, which is less exposed to the sun and is covered by moss, is more suitable for chutashi. mechanical tests showed that the shear strength perpendicular to the grain in the elm, cleavage in maple and walnut, the toughness of maple and boxwood, and the hardness in the yew had the highest values. also, boxwood had the highest density, and yew showed the least shrinkage. microscopic examinations clearly revealed the wider vessels, more homogeneity, and more interlocked grains in the root wood compared with the trunk one. the phenomenon of ahanak (ironlet) in the yew, which causes a sharp drop in its quality, is, in fact, the accumulation of special extractives in several tracheid rows. finally, the relationship between physicalmechanical characteristics and the views of the craftsmen was discussed and presence of superior properties in the selected timbres were verified.