Paavo J. Ollinmaa. (1955). Koivun vetopuun anatomisesta rakenteesta ja ominaisuuksista. Acta Forestalia Fennica vol. 64 no. 3 article id 7463. https://doi.org/10.14214/aff.7463

English title: On the anatomical structure and properties of the tension wood in birch.

Original keywords: koivu; rakenne; selluloosa; sahaus; rauduskoivu; hieskoivu; vetopuu; kemialliset ominaisuudet

English keywords: birch; Betula pendula; Betula pubescens; silver birch; downy birch; sawing; technical properties; structure; tension wood; pulp; chemical properties

Abstract | View details | Full text in PDF | Author Info

The investigation concerns with the strength of the eccentric growth accompanying formation of tension wood in silver birch (Betula pendula Roth.) and downy birch (Betula pubescens Ehrh.), behaviour of wood in wood-working machines and its macroscopic characteristics, its microscopic and sub-microscopic structure, chemical composition, resistance against certain chemicals, physical properties, and the strength characteristics of wood.

The most detrimental properties of tension wood used in wood working industry are high longitudinal shrinkage, warping, twisting and checking. The wooliness of the cut is unwanted, for instance, in plywood and furniture. In pulp industry tension wood is better raw material than normal wood because it yields more and purer cellulose than normal wood. However, it has poorer strength properties.

The PDF includes a summary in English.

Ollinmaa, E-mail: po@mm.unknown

article id 7263, category Article

I. Lassila. (1931). Studies on the influence of the forest type on the quality of pine. Acta Forestalia Fennica vol. 37 no. 1 article id 7263. https://doi.org/10.14214/aff.7263

Keywords: pine; timber quality; technical properties

Abstract | View details | Full text in PDF | Author Info

The quality of timber is very important in trade and dependable on the purpose of the timber. The article describes the influence of the forest type on the mechanic-technical properties of the timber. The studied properties are weight, the mean breadth of the annual growth rings, and the compression strength.

The percentage of the annual growth rings that is formed during the autumn is characteristic for the compression strength, and it varies accordingly on different forest types. The result from the formula of Janka depends on the forest type.

Being able to classify the timber according its quality makes it possible to have better price for it. it is also important when deciding for what purpose the timber can be used.

The PDF contains a summary in Finnish.

Lassila, E-mail: il@mm.unknown

article id 7203, category Article

I. Lassila. (1926). Puun mekaanillis-teknillisten ominaisuuksien tutkimuksesta, sen tuloksista ja tehtävistä. Acta Forestalia Fennica vol. 31 no. 4 article id 7203. https://doi.org/10.14214/aff.7203

English title: Research on mechanic technical properties of wood.

Original keywords: puuaine; puun rakenne; lujuus; puun mekaaniset ominaisuudet

English keywords: mechanical strength; technical properties of wood

Abstract | View details | Full text in PDF | Author Info

The article includes a detailed review on the technical properties of wood. The weight, water content, strength and conductivity of the wood, and the factors affecting them are discussed. The mechanical and technical properties of wood are influenced, for instance, by tree species, age and part of the tree, geographical situation, site and growth conditions of the stand, anatomical structure of the wood, and temperature. The author summarizes the topics where further research should be addressed. For instance, the forest site types developed in Finland could be utilized in studies of the mechanic technical properties of wood.

The PDF includes a summary in English.

Lassila, E-mail: il@mm.unknown

Category : Research article

article id 581, category Research article

Henrik Heräjärvi. (2001). Technical properties of mature birch (Betula pendula and B. pubescens) for saw milling in Finland. Silva Fennica vol. 35 no. 4 article id 581. https://doi.org/10.14214/sf.581

Keywords: silver birch; log; white birch; technical properties; saw milling; small-sized log

Abstract | View details | Full text in PDF | Author Info

The purpose of this study was to investigate the variation in selected technical properties of mature (age > 60 years) birch stems in southern and central Finland. Technical properties were defined as the natural external characteristics that cause differences in the usability of a certain section of stem in the mechanical wood industry, saw milling in particular. On mineral soils, birch stems in mixed stands were slightly larger than those in pure birch stands. On peatlands, however, birch stems in pure stands were larger than those in mixed stands. The average stem form of silver birch was straighter than that of white birch. Small-sized log sections of white birch, as well as those of codominant silver birch, typically contain many dead knots. On mineral soils, coniferous admixture had a positive effect on self-pruning of white birch. Self-pruning of silver birch was as good in pure birch stands as in mixed stands of spruce and birch. Occurrence of decay did not differ significantly between the two birch species. Not only silver birch, due to the growth and yield of the stand, but also vigorous and good-quality white birch, because of the possibility to provide high-quality logs, can be maintained profitably as an admixture in coniferous forests until final cutting.

Heräjärvi, The Finnish Forest Research Institute, Joensuu Research Centre, P.O. Box 68, FIN-80101 Joensuu, Finland E-mail: henrik.herajarvi@metla.fi

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