Not all formaldehyde ratings mean the same thing. In some countries, plywood is tested in a sealed glass jar with water (the desiccator method), while in others it’s tested in a large climate-controlled room (chamber method). Both produce very different numbers, which is why labels like E0, E1, or F★★★★ can be confusing. Understanding the difference of Formaldehyde Emission Tests is key to knowing whether your plywood truly meets the standards.
What “Desiccator Test” Means
The desiccator test is a method widely used in Japan and Australia/New Zealand to measure formaldehyde emissions from plywood.
- A board sample is placed inside a sealed glass container (desiccator) with a measured amount of water at the bottom.
- Formaldehyde released from the board dissolves into the water.
- After a fixed period (typically 24 hours), the concentration of formaldehyde in the water is measured.
- Results are expressed in mg/L (milligrams per litre of water).
This is why standards in these markets are written as:
- E0 = ≤ 0.5 mg/L (Australia/New Zealand)
- F★★★★ = ≤ 0.3 mg/L (Japan)
How It Differs from “Chamber Tests”
In contrast, most European, US, and Chinese standards use chamber formaldehyde emission tests such as EN 717-1, ASTM E1333, or ISO 12460.
- A plywood sample is placed in a large, climate-controlled chamber.
- Air flows through the chamber, carrying formaldehyde emissions.
- The air is then analysed, with results expressed in mg/m³ (milligrams per cubic metre) or ppm (parts per million in the air).
This is why standards in these markets are written as:
- E1 = ≤ 0.124 mg/m³ (Europe/China)
- REACH 2026 = ≤ 0.062 mg/m³ (Europe)
This test is designed to simulate real-world room conditions, while the desiccator method acts as a more artificial extraction test.
Why It Matters
- Desiccator results are usually higher than chamber results, since the water captures nearly all the formaldehyde in a small space.
- They cannot be directly converted. An E0 rating in Australia (0.25 ppm equivalent) does not guarantee compliance with Europe’s E1 chamber test.
- Some suppliers claim “E0 = CARB P2 equivalent”. This is misleading - the two use different methods, different units, and different standards.
When comparing international plywood standards:
- Always check which formaldehyde emission tests were used (desiccator vs. chamber).
- Do not assume results are interchangeable.
- For global trade, chamber-based results are generally the benchmark, while desiccator values remain valid only locally (Japan, Australia, NZ).
