Cow Muck
The addition of cow manure to lime plaster can help prevent soot staining due to a combination of factors:
Physical Barrier: The organic matter in the manure, including hair and fibers, can create a physical barrier that helps to prevent soot particles from penetrating the plaster.
Chemical Reaction: The alkaline nature of lime plaster can react with acidic components in soot, neutralizing them and reducing their staining potential.
Sealing Properties: The oils and fats in manure can help to seal the pores of the plaster, further reducing the penetration of soot particles.
It's important to note that fresh cow manure should be used, as it contains the most effective components. The manure should be well-mixed into the lime plaster to ensure even distribution.
Cow manure can prevent soot staining while allowing water vapor to pass through due to a few factors:
Physical Barrier: The organic matter in manure creates a fine mesh-like structure within the plaster. This structure is large enough to allow water vapor molecules to pass through but small enough to block larger soot particles.
Chemical Reactions: The alkaline nature of lime plaster reacts with acidic soot particles, neutralizing them and preventing them from staining the plaster. This reaction doesn't affect the passage of water vapor.
Hydrophobic Properties: Some components in manure, like oils and fats, have hydrophobic properties. These components repel water while allowing water vapor to pass through.
Overall, the combination of physical barriers, chemical reactions, and hydrophobic properties in cow manure-lime plaster allows it to effectively prevent soot staining while maintaining breathability.
The ammonia smell you're experiencing when applying lime plaster to soot is likely due to a chemical reaction between the alkaline lime and the acidic components in the soot. Soot often contains nitrogen-based compounds, which, when mixed with the alkaline lime, can release ammonia gas.
This reaction is more pronounced when the soot is wet, as the water helps to facilitate the chemical reaction. Additionally, the heat generated during the setting of the lime plaster can also accelerate the reaction, leading to a stronger ammonia smell.
To reduce the ammonia smell, you can try the following:
Ensure the soot is dry: Before applying the lime plaster, make sure the soot is completely dry. This will minimize the amount of water available for the chemical reaction.
Ventilate the area: Good ventilation can help to dissipate the ammonia gas.
Wear protective equipment: Ammonia gas can be irritating to the eyes, nose, and throat. It's important to wear protective equipment, such as a mask and gloves, when working with lime plaster and soot.