In solid wood panels, individual softwood lamellae are sorted, planed, and assembled into multi-layered boards consisting of parallel outer layers and at least one core layer perpendicular to the orientation of the outer layers. Adhesive is used to bond the lamellae. Thus swelling and shrinkage due to climatic changes is minimal. Solid wood panels have a symmetric lay-up and the thickness of the outer layers is recommended to be at least 5 mm to fulfil the requirements for loadbearing structural timber components. No open joints are allowed in the core layer.
When a tree is ready for harvesting and has been felled, the trunk is usually debranched and cut into butt log, middle log, top log and one to three sections of pulpwood. Crown and branch wood can be collected up to be chipped and used as forest fuel. Smaller trees that are felled during thinning, for example, are cut into pulpwood or small-dimension sawlogs (top diameter 120–200 mm).
Sweden currently has around 140 sawmills, which produce over 10,000 cubic metres of sawn wood products per year. Production is being concentrated among ever fewer companies, with the individual sawmills specialising in wood types and product groups. Of the total production in Sweden of around 17 million cubic metres sawn wood products (2011), the 10 biggest companies account for around 60 percent and the 20 biggest companies account for around 80 percent of the country’s production. Alongside the industrial sawmills is the smaller-scale production for local and domestic purposes at a number of small sawmills. Different cutting methods are used at the sawmills. The circular saw dominates among the small sawmills, while reducer band saws and reducer circular saws are most common in larger sawmills. The reducing process mills away the circular segments outside the rectangle, which is then divided up into planks and boards using band or circular saws. The profiling saws cut a profile out of the log cross-section, and then the circular saws divide the planks and boards up into different cross-sectional dimensions. Profiling saws are very much on the up, with older sawmill methods becoming more uncommon. See also Surface structures in the chapter Quality and range.
This board is obtained by cutting the log in the first place. The main distinguishing feature is the presence of bark and rough edges.
New fashion for undedged lumber
Regardless of the type of saw in the sawmill, the unedged board is the first output product.
Next, the woodworker is faced with the question – to leave the unedged board as it is or to process it later.
The last 5-10 years, due to the fashion on the live edge, the scope of application of unedged boards has expanded. If earlier it was a product of fast processing or a product for extremely thrifty craftsmen, now the unedged board is included in the list of mandatory goods in the carpentry shop.
So, unedged board in its original form is used for tables, table tops, window sills, benches and decor.
Price and other features of unedged boards
The cost of unedged boards is lower than of the edged ones. In the manufacture of the obtained maximal output coefficient from the barrel. If in the trunk 1 m3 of wood, then the output unedged board is 0.85 m3.
However, the unedged wood is more difficult to dry. The drying process is affected by any features of the wood. One knot is able to change the geometry of the whole board in the process of drying. Therefore, drying of the unedged board requires a special approach.
In the European classification, unedged board sometimes has the designation B, from the word Boul. In this case, we are talking about a stack of boards, sawn from one log.