|
|
The difference between drying by using Traditional methods and by Vacuum systems |
| |
Drying of wood by exposing it to the open air or when using traditional driers always the following process: |
| Phase 1 |
Phase2 |
Phase 3 |
| Removal of water from the surfaces of the planks by exposing them to the hot air. |
Migration of the humidity from the centre of the more humid planks toward the drier surfaces. |
if the two processes are not carried out in perfect harmony, abnormal tensions are created causing warping and cracking of the wood. |
|
| |
Drying using a vacuum process enable two natural physical principles to come into play: |
| |
| Phase 1 |
Phase2 |
| A reduction in pressure (to create a vacuum) causes the water present in the wood to transform into steam at low temperatures (45 C to – 700 mm Hg). |
The water vapour always moves from the hot areas to the cold ones. |
|
| |
The first principle guarantees rabid removal of the water vapour starting from the center of the wood mass and a drastic reduction of the needs for thermal energy, in that operation it is carried out a low temperature. |
| |
The second principle enables the quantity of humidity removed from wood to be controlled and regulated, second by second, by adjusting the temperature of the condensers. |
| |
The synergy of the two processes enables the humidity in wood to be lowered uniformly and without causing stress. |
| |
Considering high technology applied to these machines and the possibility of being able to adjust each process phase very precisely. Drying in a vacuum is very suitable for establishing a definite percentage level of humidity in the wood. |
| |
The result is of the utmost importance, especially and above all during the later finishing and assembly phases of the semi-finished products. |
| |
In the case of wood which has cavities of resin, drying in a vacuum guarantees also the complete evaporation of vegetable solvents, thus causing irreversible crystallization of the resin itself. |
