The "weeping" or "sweating" issue is a significant problem primarily associated with older-style Magnesium Chloride boards, a type of Magnesium Oxide board.
It is a process where the board draws moisture from the air, causing salty, corrosive liquid droplets to form and leak from its surface.
What Is Weeping or Sweating?
The question has already been answered with sufficient detail in the previous turn. I will provide the consolidated answer.The "weeping" or "sweating" issue is a significant problem primarily associated with older-style Magnesium Chloride boards, a type of Magnesium Oxide board.
It is a process where the board draws moisture from the air, causing salty, corrosive liquid droplets to form and leak from its surface.
What Is Weeping or Sweating?
The phenomenon is also referred to as "crying boards" and is a form of deliquescence. It occurs through the following mechanism:
- Hygroscopic Binder: MgCl2 is a highly hygroscopic salt, meaning it has a strong chemical affinity for water vapor in the air.
- Moisture Absorption: When the board is exposed to high humidity (typically above 80% RH), the residual or unreacted MgCl2 salt within the board matrix actively absorbs excessive amounts of moisture from the surrounding atmosphere.
- Leaching Corrosive Fluid: The absorbed water dissolves the magnesium salts, creating a concentrated salty, corrosive water solution (leachate) that migrates to the board's surface and drips off.
Consequences of Weeping
The leaked, chloride-rich solution is highly destructive, leading to:
- Corrosion: Severe and rapid corrosion of metal fasteners, screws, and steel framing.
- Degradation: Moisture uptake and eventual degradation of adjacent materials, particularly wooden structural members.
- Staining & Mold: Visible surface staining and promotion of mold growth.
How Mgo Sulfate Board Prevents It
MgO Sulfate Board (or MgSO4 board) is an improved, chloride-free formulation that completely resolves the weeping problem by replacing the hygroscopic binder with a chemically stable one.
| MgCl2 (Chloride) Boards | MgSO4 (Sulfate) Boards |
| Uses Magnesium Chloride MgCl2 as the binder (Sorel cement). | Uses Magnesium Sulfate MgSO4 as the binder. |
| Highly Hygroscopic → Weeping | Significantly Less Hygroscopic →No Weeping |
| Chloride ions are present → High Corrosion Risk | Chloride ions are absent → Zero Corrosion Risk |
By using Magnesium Sulfate instead of Magnesium Chloride, the board eliminates the primary agent (MgCl2) responsible for attracting and dissolving atmospheric moisture, thus ensuring superior dimensional stability and moisture resistance in high-humidity environments
More information, please visit at www.hocre-board.com or send message by whatsapp +86 15001321220
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