" " wisno wood furniture finishing: Tips and consideration to build the wood kiln dry.

Friday, April 6, 2012

Tips and consideration to build the wood kiln dry.

The (wood) kiln dry is a large building that requires special equipment and tools. To build and operate the kiln dry is considered big work. The fact is the kiln dry is the most important facility to process the wood. But, then we need to do carefully calculation to find the best suitable facility according to our need. There are many method to drying the wood and many type of kiln dry are available.  We have written about the drying of wood (kiln dry in the woodworking industry), and now in this article we want to share about the considerations needed when we are going to build a dry kiln.

Here are some tips and consideration when we want to build the kiln dry to the wood.
  • Calculate the volume of the dry wood needed.
The volume of dry wood, the size and the required moisture content of the wood is the first thing to be considered when we are going to build a kiln dry. The calculation to the building, facilities and types of the kiln is mainly based to the capacity and the type of the kiln dry. Some type of kiln dry is more proper to work at low wood m.c., while some types are more economic to dry the wood at the moderate moisture content that may be enough for construction wood. Pre drier or naturally drier may quite well to dry the wood for construction that works well at about 20% m.c. level. But the woods for woodworking, furniture or architectural product always need the lower moisture content (m.c. level at 8%-10%).
The building and the equipment for the kiln dry is calculated based to the capacity of the kiln. The room, the heater and the type of kiln dry has to follow the calculation result from the capacity of the kiln dry.

  • The species of the wood.
Wood is a life material that has unique properties. Each type of wood has different properties and may require different drying process. Generally, wood can be divided into two types: the hard wood and soft wood. The hard wood usually has higher risk to get cracked, swelling, splitting, honeycombing or other defect caused by too fast drying. The carefully drying schedule for the hard wood is needed.  Especially when we are going to use the wood for the visible part which need the best performance dry wood.
The softwood usually can be dried in quicker schedule. It less risk to get defect and naturally  can be dried faster. The softwood is also most used for the interior part at which some small defect is not a problem.
The data of wood moisture content versus the volume of the wood is very important. The wood with big shrinkage is more risk to get damaged by the too fast drying. The wood hardness is also important; the harder wood usually is more risk to be cracked or splitting.

  • Environmental conditions.
Wood is a hygroscopic material. The naked wood will always absorb or release its water to make balance with its environmental humidity. Then we need to find the data about the environment condition especially the air humidity. Wood will release his moisture if it is placed in the open air until its moisture content is in balance with the air humidity. The moisture content of the naked wood will fluctuate according to its environment air humidity changing.
The data of the air humidity can help us to find the final m.c. needed. If the wood is going to be used in the same area, then we can dry the wood until it reach the moisture content in balance with the average of air humidity in the area.  But if the wood is going to send to another place then we may need to make some treatment for the dry wood. The dehumidifier room may be needed keep the wood m.c.
  • The types of kiln dry.
There are several types of kiln dry can be selected to get the most suitable facility according to our need. For the areas that are quite hot with lot of sunshine, the solar kiln dry could be considered as good choice. It uses the solar energy to reduce the energy consumption.
For the small volume, the dehumidifier kiln dry is good option. It less use energy and can give the low wood m.c. If the rapid drying is needed, then the high temperature or vacuum kiln dry kiln is the choice. The Vacuum kiln dry can dry quickly, but requires relatively expensive operating costs with small capacity.
To drying the wood with large volume, then conventional kiln dry is still the best choice. It is quite simple, can be set to arrange the drying schedule. It can be combined with the pre drier or naturally drier. To save the energy consumption we can use the wood wastes from the woodworking process as the fuel.  

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