Video: Determination Of Moisture Content And Drying Of Wood
2023 Author: Douglas Hoggarth | [email protected]. Last modified: 2023-05-24 11:23
DETERMINATION OF WOOD MOISTURE
There are several ways to determine the moisture content of wood. In domestic conditions, they use a special device, an electric moisture meter. The operation of the device is based on a change in the electrical conductivity of wood depending on its moisture content. The needles of the electric moisture meter with the electric wires connected to them are inserted into the tree and an electric current is passed through them, while the moisture content of the wood in the place where the needles are inserted is immediately noted on the scale of the device.
Many experienced carvers measure wood moisture by eye. Knowing the types of wood, its density and other physical properties, it is possible to determine the moisture content of wood by weight, by the presence of cracks at the end or along the grain of the wood, by warping and other signs. By the color of the bark, its size and the color of the wood, one can recognize ripe or freshly cut wood and the degree of its moisture.
When processing a s / m with a plane, its thin shavings, compressed by hand, are easily crumpled - this means the material is wet. If the chips break and crumble, this indicates that the material is dry enough. When cross-cutting with sharp chisels, attention is also paid to the chips. If they crumble or the wood itself is chipped off, this means that the material is too dry.
Very wet wood is easy to cut, and a wet mark is noticeable at the cutting site from the chisel. But it is unlikely that it will be possible to get a high-quality thread as a result, since cracking, warping and other deformations cannot be avoided.
Dry wood has high strength, shrinks less, does not rot, sticks easily, finishes better, and is more durable. Any wood of a wide variety of species is very sensitive to changes in the humidity of the environment. This property is one of the disadvantages of timber. With high humidity, wood easily absorbs water and swells, and in heated rooms it dries out and warps. Indoors, the moisture content of the wood is sufficient up to 10%, and in the open air - no more than 18%.
There are many ways to dry wood. The simplest and most affordable - natural type of drying - atmospheric, airy. It is necessary to dry wood in the shade, under a canopy and in a draft. When dried in the sun, the outer surface of the wood heats up quickly, while the inner remains moist. Due to the difference in stress, cracks are formed, the wood quickly warps.
Boards, beams, etc. p / m are stacked on metal, wooden or other supports with a height of at least 50 cm. Boards are stacked with the inner layers up to reduce their warpage.
It is believed that the drying of boards placed on the edges is faster, since they are better ventilated and the moisture evaporates more intensively, but they also warp more, especially material with high humidity. It is recommended to compact a stack of p / m, harvested from freshly cut and live trees, with a heavy load to reduce warpage.
With natural drying, cracks always form at the ends, to prevent cracking and preserve the p / m, it is recommended to carefully paint the ends of the boards with oil paint or soak with hot linseed oil or bitumen to protect the pores of the wood. The ends must be processed immediately after the cross cuts into the cut. If the tree is distinguished by high humidity, then the end is dried with a blowtorch flame, and only then painted over.
The trunks (ridges) must be debarked (cleaned of bark), only at the ends they leave small belts-sleeves 20-25 cm wide to prevent cracking. The bark is cleaned so that the tree dries out faster and is not affected by beetles. The trunk, left in the bark, in relative warmth with high humidity, quickly decays, is affected by fungal diseases.
After atmospheric drying in warm weather, the moisture content of the wood is 12-18%.
There are several other ways to dry wood.
Or steaming has been used in Russia since ancient times. The workpieces are sawn into pieces, taking into account the size of the future product, they are laid in ordinary cast iron, sawdust from the same workpiece is poured, poured with water and placed in a heated and cooling Russian oven for several hours at t = 60-70C. In this case, “leaching” occurs - the evaporation of wood; natural juices come out of the workpiece, the wood is colored, acquiring a warm, thick chocolate color, with a pronounced natural texture pattern. Such a workpiece is easier to process, and after the end of drying it cracks and shrinks less.
The workpieces are dipped into melted paraffin and placed in an oven at t = 40C for several hours. Then the wood dries out for a few more days and acquires the same properties as after parking: it does not crack, does not warp, the surface becomes tinted with a distinct texture pattern.
Steaming method in linseed oil
Cookware made of wood steamed in linseed oil is very water resistant and will not crack even with daily use. This method is still acceptable today. A blank is placed in a container, poured with linseed oil and steamed over low heat.