Why Kiln Dried Logs?

By Author: Paul Hayward
Total Articles: 2
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Before we understand why we need kiln dried logs, we need to know the definition of green wood. Green wood is a type of wood that is cut recently. The lumber used for constructional purposes need to be air dried appropriately before putting them to use. Since this is a time consuming process, kiln-drying is used to speed up the drying of wood.

A brief description of the kiln drying process

Sawn lumber is placed into kilns where hot air is circulated. Temperatures in the kiln range from 120 degrees Fahrenheit to 190 degrees Fahrenheit based on the stage of drying. The temperature and relative humidity is controlled to reach the wood’s equilibrium moisture content (EMC). Based on this process, we can conclude that kilns play a very key role in the wood’s moisture content measurement and management process. A professional wood worker has to select the right type of kiln based on the application of the end product.

Kiln dried lumber offers several advantages
• Kiln drying is probably the most efficient method used to prevent stains occurring on lumber.
• Wood with moisture removed weighs ...
... less compared to green wood. Hence, this lowers the overall transportation cost.
• Lumber kilns helps in minimizing waste and increasing profitability.
• Lumber kilns help lumber manufactures in controlling the quality of the drying processes and the wood that passes through these kilns.
• The kiln drying process enables wood to withstand the impact of glues, bonding agents, and fasteners.
• Wood that has gone through kiln drying is stronger and stiffer than green wood. Because of this, kiln dried lumber is recommended for woodworking tasks.
• Kiln dried logs produce more heat than the standard logs.
• These logs burn more efficiently.
• Kiln dried logs burn longer, which in turn provides more warmth to the end users during the winters.
• Kiln dried logs burn more cleanly i.e. it leaves very little contamination.
• The price of kiln dried lumber remains the same throughout the year; it does not change from season to season.
• Kiln drying helps woodworkers in avoiding defects like cupping, bowing, twisting, crooking, spring, diamonding, and collapse (a defect that is a result of the physical flattening of fibers).

Different types of kiln drying
• Dehumidification kiln – It is a closed-loop chamber that uses a heat pump to remove moisture from the air using the cooler side of the evaporator. The temperatures in these kilns range from 100 degrees Fahrenheit to 160 degrees Fahrenheit.
• Vacuum kiln – These kilns can be the fastest kilns to dry the wood. In a vacuum, water boils at a low temperature.
• Solar kiln – This is a combination of the dehumidification kiln and the vacuum kiln. They usually contain a high-temperature fan that is used for drying. They are cheaper but are slower due to the weather.
• Conventional wood dry kilns – There are two types of conventional kilns in the market: the sideloader or the tram construction type. Sideloader is usually used to dry hardwood lumber and the tram construction type is used to dry softwood lumber. Modern conventional kilns can dry 1-inch-thick (25 mm) green lumber in 10 hours and bring down its moisture content to 18%.
• Radiowave kilns – They use microwaves to dry lumber. Because these kilns use electricity to provide the heat for vaporization, their operation costs are higher compared to the other kilns.

Meters to measure the moisture in wood

A wood moisture meter plays a very important role in measuring the moisture content in any type of wood. Kiln operators use these meters to conduct spot checks on kiln-dried lumber in order to ensure that there is a balance between the moisture content and the relative humidity (based on the products application specification). Any kind of imbalance between the two might jeopardize the strength of the wood.

The perception of kiln-dried lumber is divided. However, this type of lumber offers a list of unique benefits (as mentioned above). We strongly suggest that a professional woodworker or a hobbyist conduct enough research before selecting the wood for the task in hand. Also, we strongly recommend that wood workers purchase moisture meters to test the wood they intend to purchase. There are two kinds of meters, pin meters and pinless meters. The advantage of pinless meters is that they don't damage the wood that has to be tested.