A pocket , or a tar pocket (unofficial), or a chamois [1] (unofficial) is a cavity inside or between annual layers of wood filled with resin or gum . It is usually located close to the periphery of the trunk .
Content
Building
On the tangential cut it looks like a flat oval recess, on the radial - like a narrow longitudinal slit, on the end - like a short arcuate cavity, accompanied by a slight bend of the annual rings adjacent to the outside of the trunk. Along the trunk, the length of the resin pocket is slightly larger than the circumference. In the lateral direction it can have a length of up to 10 cm, a depth of up to 7 mm.
By the number of exits to the surface of the material, one-sided and through resin pockets are distinguished. A one-sided resin pocket extends onto one or two adjacent sides of the lumber or part; through - on two opposite sides.
Appearance
Resin pockets are characteristic especially for spruce . Also found in wood are pine , Siberian cedar and larch . The reason for their occurrence is considered to be cambium damage due to swaying of the tree from the wind and overheating of trees growing at the edge , where tar pockets are found especially often.
A large number of pockets indicates a poor connection between the annual layers and may be accompanied by peeling cracks . The abundance of tar pockets in the upper part of the trunk [2] can be caused by a type of tar tree cancer - a catwalk caused by the fungi Cronartium flaccidum and Peridermium pini [3] [4] .
Impact on wood quality
The contents flowing out of the resin pockets spoil the surface of the products and prevent their external decoration, cladding and gluing, soiling tools. Reduces the grade of small high-quality lumber and plywood . In small parts, resin pockets can reduce the strength of wood. The strength of large parts is slightly affected.
When the wood is heated, the resin can leak out of the pockets even years after the manufacture of the part, seeping through the oil paint .
In the manufacture of carpentry , the resin from the pockets is removed and replaced with putty .
Measurement
In lumber, resin pockets are counted in quantity in pieces per 1 m of length or on the entire side of the assortment, the largest of them are measured in length, width and depth. The veneer measures the width and length and takes into account the number of pockets per 1 m 2 or the entire sheet. It is allowed to measure one of these parameters, if this is due to the specifics of the assortment.
Notes
- ↑ Serenice . dic.academic.ru. - The modern explanatory dictionary of the Russian language Efremova, 2000. Date of treatment May 8, 2013.
Vice of wood. Album / Miller V.V., Vakin A.T. - 1938. - Tab. 129. - ↑ Spindle-tree // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
- ↑ Defects of wood. Album / Miller V.V., Vakin A.T. - 1938. - Tab. 130-131.
- ↑ Resin Cancer // Forest Encyclopedia.
See also
- Sap
Literature
- Vakin A.T., Poluboyarinov O.I., Solovyov V.A. Wood defects. - Ed. second, reslave. and add. - M .: Lesn. industry, 1980 .-- 197 p.
- Vakin A.T., Poluboyarinov O.I., Solovyov V.A. Album of wood defects. - M .: Lesn. industry, 1969 .-- 165 s.
- Vice of wood. Album / Miller V.V., Vakin A.T .. - M. - L .: Catalogizdat NKTP USSR, 1938. - 171 p. - 3500 copies.
- Pockets // Forest Encyclopedia / Ch. ed. Vorobyov G.I .; Ed. col .: Anuchin N.A. et al. - M .: Sov. Encyclopedia, 1986.- 631 p.
Links
- GOST 2140-81 . www.complexdoc.ru. - Visible wood defects. Classification, terms and definitions, measurement methods. Illustration. Date of treatment April 22, 2013. Archived May 2, 2013.
- Resin pocket . Glossary.ru. Date of appeal April 24, 2013.