7.2. Types of Seasoning

A. Natural Seasoning (Air Seasoning)

• Timber is stacked in well-ventilated, shaded areas with adequate spacing.
• End coatings (tar/paint) may be applied to prevent end cracking.
• Duration: 6–12 months or more depending on species and size.
• Advantages:
  • Economical
  • Environment-friendly
• Disadvantages:
  • Slow
  • Weather dependent
  • Susceptible to insect/fungal attacks during process

Natural seasoning, also known as air seasoning, involves drying timber by stacking it in shaded and well-ventilated areas. The spacing between timber pieces is important for airflow which helps in moisture evaporation. To prevent end cracking—a common issue due to uneven drying—coatings like tar or paint may be applied to the ends of the timber. Natural seasoning can take a significant amount of time, typically ranging from 6 to 12 months, and this duration greatly varies depending on the type of wood and its size. While it's an economical and eco-friendly method, it has drawbacks. The process is slow and can be influenced by weather conditions, making it less reliable in certain climates. Additionally, the timber can be vulnerable to insect attacks and fungal infections during the long drying period.

Imagine drying clothes on a clothesline versus using a dryer. Air drying clothes can take a longer time and is dependent on the weather; if it's rainy or humid, they take even longer to dry. However, it is more environmentally friendly and doesn’t consume energy. Similarly, natural seasoning is like air drying timber: it takes time but is cost-effective and eco-friendly.

B. Artificial Seasoning

• Accelerated drying using controlled heat, humidity, and air flow.

1. Kiln Seasoning:

   • Timber is placed in a kiln with regulated temperature/humidity.
   • Most effective and controlled method.
   • Types: Compartmental kiln, Progressive kiln
   • Advantages:
     • Quick and uniform
     • Can treat large quantities
     • Reduces defects like cracking
   • Disadvantages:
     • Expensive
     • Requires skilled supervision

2. Boiling:

   • Timber is boiled in water or steam-chambered for hours.
   • Opens up wood cells and allows rapid moisture loss.
   • Effective but may degrade strength slightly.

3. Chemical Seasoning:

   • Uses salt solution or urea compounds to draw moisture.
   • Good for dense woods.

4. Electrical Seasoning:

   • High-frequency electric currents evaporate water inside the timber.
   • Fast but suitable only for small sections.

Artificial seasoning refers to methods that speed up the drying of timber using controlled environments. This includes techniques like kiln seasoning, boiling, chemical seasoning, and electrical seasoning. In kiln seasoning, timber is placed in a kiln where both temperature and humidity can be carefully adjusted. This method is efficient and can be applied to large batches of wood while minimizing defects such as cracking. However, it can be costly and requires knowledgeable supervision to operate effectively. Boiling involves immersing timber in water or steam for hours, which helps swiftly release moisture but can weaken the wood's structural integrity somewhat. Chemical seasoning uses substances like salt to draw out moisture, especially beneficial for denser types of wood. Finally, electrical seasoning uses electric currents to accelerate moisture evaporation, but it is primarily limited to smaller pieces of timber.

Think of how you would quickly cook vegetables using a pressure cooker compared to boiling them on a stove. The pressure cooker cooks them faster, achieving the same result but in a fraction of the time. Artificial seasoning is like using a pressure cooker for timber—it accelerates the drying process, allowing for quicker preparation for construction, but it requires the right tools and know-how.

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