Moisture Absorption and Water Absorption-Key Factors of Mgo Boards Quality

The Secret of Moisture absorption and Water absorption -Key Factors of Mgo Boards Quality

When you evaluate the sulfate mgo boards, these two conceptions are very important, namely moisture absorption and water absorption. Usually the superior quality sulfate mgo boards can meet the requirements. Like MGOTECH sulfate MgO boards moisture aborption <0.5% and water absorption <26% according to America building codes.

Moisture aborption and Water absorption

Moisture absorption and water absorption are two different conceptions. And they all can tested according to ASTMC1185 sections.

Moisture Content Definition:

Moisture content is the percentage of water naturally contained in the board under ambient temperature and humidity, compared to its dry weight. It indicates the equilibrium moisture level in normal use conditions.

If Moisture Absorption: <0.5% is excellent and considered a high-quality standard. For high-grade MgO boards (especially flooring and interior applications), ASTM C1185 / EN 12467 often require Moisture Absorption ≤0.5–1.0%.

<0.5% shows the board barely takes up moisture from the air → very good dimensional stability.

Water Absorption Definition:

Water absorption is the percentage of water absorbed by the board after being immersed in water for a specified time, compared to its dry weight. It reflects the board pore structure and sensitivity to moisture. Common test methods: ASTM C1185, EN 12467. In the market, typical MgO boards have water absorption levels of 20–35%.

 <26% means: The product is in the qualified to good range, better than common boards (>30%). Indicates a relatively dense structure and lower risk of swelling after water exposure. Suitable for applications requiring better water resistance (e.g., flooring substrate, wall panels).

Summary

Water Absorption → measures water resistance and density, lower is better.

Moisture Content → measures natural stability in storage/installation, lower is better (but not too low to avoid brittleness).