1. Logging & Sawing
Logging: Rubber trees are felled after ceasing latex production. Processing must occur promptly, as fresh rubberwood is highly susceptible to blue stain and decay.
Sawing: Logs are sawn into rough boards (square timber) of desired thickness. Radial or tangential cutting is typically employed to minimize warping.
Key Point: The time from felling to factory processing should be minimized. Ideally, sawing and tank treatment should be completed within 24-48 hours.
2. Preservative Treatment - The Most Critical Step
This is the most important process distinguishing rubberwood from other woods. Rich in sugars and starches, rubberwood is a breeding ground for fungi and pests.
Method: Typically employs pressure impregnation or vacuum pressure treatment.
Chemicals: Uses specialized preservatives (e.g., boric acid/borax solutions, or eco-friendly ACQ/CCA compounds). Furniture-grade applications predominantly utilize boron-based compounds due to their low toxicity and effective insect/fungus resistance.
Process:
Place rough boards into treatment tanks.
Evacuate air from wood cells via vacuum extraction.
Inject preservative solution under pressure to force penetration deep into the wood.
Maintain pressure for a specified duration to ensure adequate chemical loading.
Purpose: Eliminate existing insect eggs and fungi while imparting long-term resistance to insect infestation and mold growth, and enhancing dimensional stability.
3. Drying Process
Treated wood contains extremely high moisture content and requires drying.
Preheating: Sometimes performed first to soften the wood.
Kiln Drying: Wood is placed in a drying kiln where temperature, humidity, and airflow are controlled to reduce moisture content to the target level (typically 8%-12%, depending on the climate of the destination market).
Stress Relief: Humidification treatment is applied during the later stages of drying to relieve internal stresses in the wood, preventing cracking and warping.
Note: Rubberwood should not be dried too rapidly, as this can cause surface cracking.
4. Grading & Sorting
Dried boards undergo manual or machine screening.
Rejection: Remove dead knots, severe cracks, decay, and areas with incomplete blue stain removal.
Grading: Classify boards into grades (e.g., Premium, Grade 1, Grade 2) based on grain, color, and defect levels for use in different product tiers.