How to treat the green bar tree for wooden flooring

There are three kinds of wood cracking: end cracking, surface cracking and internal cracking, and the good ways to prevent wood cracking are:

Terminal fissures (cleavage or longitudinal fissures).

When the moisture content of the end is lower than the fiber saturation point, the end cell will begin to shrink, and when the dry shrinkage stress reaches the strength limit of the wood, the end crack will occur, that is, the longitudinal crack occurs at the heart of the pith or the coarse wood ray or along the outer plate surface. It is almost inevitable that the medullary center will have terminal fissures along the medullary core, which is where the radiated parenchyma cells are most concentrated, and the lateral tensile strength is extremely low.

The following measures can be taken to prevent end cracking:

If permitted, it is best to re-cut the thick plate into thin plates or small square lumbers for drying, which can effectively prevent end cracks and other drying defects.

Before the kiln is dried, the part that has been cracked is cut off, because the original end crack is easy to continue to extend.

Apply paraffin oil or thick paint to the ends of the boards where there is no end cracking to prevent water from evaporating from the ends.

When loading, the spacer at the end of the pile should be pressed as close to the end as possible and aligned up and down.

When loading the kiln, the end of the lumber pile and the timber pile should be as close as possible to prevent the air flow from short-circuiting the gap between the lumber pile, so as to avoid the end drying too quickly.

For hard hardwood or thick plates that are prone to end cracking, try to use a softer drying process, and pay attention to timely humidification treatment.

Surface fissure. Surface cracks are longitudinal cracks that occur along wood rays on the outer surface of sawn timber (usually the outer section of a chord cutting plate). It is caused by excessive surface tensile stress in the early stage of drying. When the surface tensile stress gradually decreases from the maximum value, the surface crack also begins to gradually decrease.

The way to prevent surface cracking is to not be too hard in the early stage of the benchmark, and pay attention to controlling the development of drying stress. Intermediate humidification should be carried out when the initial moisture content is reduced by about 1 3, because at this time the surface tensile stress may reach its maximum. For thick plate or hard hardwood, intermediate treatment should be carried out several times, either for every 10% reduction in moisture content or every 2 to 3 days to eliminate surface tensile stress.

Internal fissure (honeycomb fissure).

Wood internal fissures occur inside the wood and crack along the wood rays, like honeycomb, also called honeycomb fissure. There are no signs of cracking on the surface, and it can only be found if it is sawn.

The way to prevent it is to carry out intermediate treatment in time in the middle and late stages of kiln drying to relieve surface hardening. For sawn timber with a high thickness, especially for hard hardwood, the drying temperature should not be too high in the later stage.

First of all, we should understand the reasons why the wood of the green bar tree is easy to crack. We know that the reason for wood cracking is not only caused by uneven stress in wood, but also due to uneven shrinkage of wood tissue when drying. When the wood of the green oka tree dries and shrinks, the tissues such as the wide wood rays are weak, and cracks are easily torn from it and cracks are formed (it can be observed that the cracks are mostly open along the wide wood ray parts).

How to avoid cracking of the wood of the green bar tree? There are three principles: first, the harvesting time should be selected in the winter when the water content of the trees is the lowest; the second is to sawn the raw timber into large-size blanks as soon as possible; Third, artificial dehydration should use superheated steam drying, and the drying treatment time should be slow and not urgent.