Webinar Recap
Efflorescence or latex migration: how to tell the difference, repair, and prevent
The NTCA webinar titled "Efflorescence or Latex Migration: How to Tell the Difference, How to Repair, and How to Prevent" offers an in-depth look at two common issues in the construction and tile industries. Sponsored by MAPEI and led by Nick Valenti, a technical expert with over 35 years of experience in sealers and cleaners, the session was designed to help professionals understand, differentiate, and address these issues.
Valenti chose this topic due to s the persistent nature of efflorescence and latex migration, particularly with the increasing use of large-format tiles and highly-modified setting materials. These advancements have led to more latex involvement and less room for moisture to escape, making it crucial to identify and address these issues effectively.
Understanding efflorescence
Efflorescence is defined as the migration of soluble salts to the surface of porous materials like concrete, stone, and brick. The term, derived from the French word meaning "to flower out," often refers to the visible white deposits that form on surfaces, sometimes called an "efflorescence bloom." Portland cement-based setting materials and grouts, concrete sub-surfaces, many natural stones, and clay tiles contain free lime and/or soluble salts. These minerals are brought to the surface by capillary action and become visible after water has evaporated. Efflorescence is primarily considered a cosmetic issue rather than a structural or setting concern. However, understanding its causes is essential to effectively manage and prevent its occurrence.
The term “efflorescence” is derived from the French word meaning "to flower out." It often refers to the visible white deposits that form on surfaces, sometimes called an "efflorescence bloom."
Causes of efflorescence
According to the Portland Cement Association, three key factors contribute to efflorescence: soluble compounds, moisture, and evaporation or hydrostatic pressure. These elements work together to bring soluble salts to the surface:
• Soluble compounds: Minerals (free salts) in the masonry, stone, grout, setting material, or adjoining materials.
• Moisture: Water is necessary to dissolve and transport the soluble salts to the surface.
• Evaporation or hydrostatic pressure: This drives the moisture through the system, depositing the salts on the surface as a white residue.
Three key factors contribute to efflorescence: soluble compounds, moisture, and evaporation or hydrostatic pressure. These elements work together to bring soluble salts to the surface.
If any of these factors are removed from the equation, efflorescence cannot occur. Additionally, ConcreteConstruction.net identifies a fourth contributing factor: sustained cool temperatures, usually below 50 degrees Fahrenheit. During cooler months, slower evaporation can prolong the drying process, keeping materials moist for extended periods and increasing the likelihood of efflorescence formation.
There are two types of efflorescence, primary and secondary. In primary efflorescence, the salts are already present in the materials, and the water comes from sources such as moisture in the setting materials, pipe leaks, poor flashing installation, or external sources that bring salts to the surface. Primary efflorescence can also occur during the initial curing phase of cement-based materials, and brick or stone.
Secondary efflorescence is a reverse process where the salts originate from external sources and then are carried inside the system in solution. It results from invasive materials, such as chlorides. De-icing salts are an example.
Latex migration
Latex migration, while similar in appearance to efflorescence, involves the movement of latex from modified setting materials to the surface of tiles or grout. This occurs when moisture from the setting materials causes the latex to rise and deposit on the surface as a white or hazy film.
Repair and prevention
Repairing efflorescence typically involves cleaning the affected surface with appropriate cleaners, such as those from MAPEI's UltraCare line, which Valenti represents. In contrast, addressing latex migration often requires removing the haze with specific cleaning agents designed for latex residues.
Preventing both issues begins with proper material selection and installation practices. For efflorescence, using low-alkali cement, ensuring proper drainage, and controlling moisture exposure can significantly reduce the risk. For latex migration, careful attention to curing times, humidity levels, and the use of recommended setting materials can help prevent the problem.
Understanding the causes and solutions for efflorescence and latex migration is essential for construction and tile professionals. By recognizing the differences between these issues and implementing effective prevention and repair strategies, professionals can maintain the aesthetic and structural integrity of their projects.
Watch this webinar and other NTCA videos on the NTCA YouTube channel.
View the full webinar on NTCA's YouTube channel