Consultants and Expert Witnesses

Understanding White Substances in Pool and Spa Finishes: Beyond the Usual Suspects

The pool industry has long been plagued with a persistent issue: white substances leaching out of tiles, stones, and concrete in and around pool and spa finishes. This phenomenon, often appearing after the pool is filled with water and put into service, has sparked endless debates regarding its root causes. Common culprits cited include calcium, efflorescence, lime, and minerals. However, another significant but less recognized cause is polymer re-emulsification, a process that many industry professionals overlook. This article explores the complexities of polymer re-emulsification and its impact on pool and spa finishes.

Common Theories on White Substance Leaching

The leaching of white substances from pool finishes is often attributed to several common causes:

1. Calcium: High calcium levels in the water can precipitate and form deposits on pool surfaces.
2. Efflorescence: This is the migration of salts to the surface of porous materials, where they form a white, powdery deposit.
3. Lime: Similar to efflorescence, lime can also migrate to the surface, particularly in cementitious materials.
4. Minerals: Various other minerals present in the water or construction materials can also contribute to the white deposits.

While these causes are valid, they do not encompass the entirety of the issue.

The Role of Polymer Re-Emulsification

A more modern and less commonly recognized cause of white substance leaching is polymer re-emulsification. Most modern cements, thinsets, and grouts contain polymers such as superplasticizers, latexes, and redispersible powders. These additives enhance the performance of tile and stone installation products by improving strength, bonding, and shrinkage control. However, they require adequate time to cure before being exposed to water. If these materials are subjected to water prematurely, especially in total submersion scenarios, the polymers can re-emulsify and migrate to the surface as a white substance.

Key Factors and Implications

Understanding polymer re-emulsification requires consideration of several critical factors:

1. Submersion vs. Wet/Dry Cycles: Fully submerged tiles will leach uncured polymers, but not as quickly as tiles subjected to wet/dry cycles. The alternating exposure to water and air in wet/dry cycles accelerates the leaching process due to capillary action.
2. Curing Time for Large Tiles and Stones: Large tiles and stones pose a unique challenge because the thinset used to adhere them requires more time to cure fully. The perimeter of the tile, which has access to air, may harden relatively quickly, but the thinset behind the stone or large tile remains trapped and cures much more slowly. This slow curing process increases the likelihood of polymer re-emulsification.
3. Indefinite Leaching: Re-emulsified polymers can leach indefinitely unless they are allowed to fully cure. This continuous leaching can ruin the surface of the tile, leading to long-term aesthetic and structural issues.
4. Impact of Homeowner Patience: Homeowners often play a significant role in the leaching of substances due to impatience. The desire to get pools up and running prematurely can lead to exposure of uncured materials to water, exacerbating the problem.

Addressing the Issue

To mitigate the issue of white substance leaching, it is crucial to adopt a comprehensive approach that considers both traditional and modern causes. Here are some strategies:

1. Proper Curing Time: Ensure that all cementitious materials are given adequate time to cure before being exposed to water. This may involve educating homeowners and pool installers about the importance of patience and proper curing procedures.
2. Material Selection: Use high-quality materials with known performance characteristics. Choose products that are specifically designed for submerged conditions and have a proven track record of minimal leaching.
3. Environmental Control: Manage environmental conditions during the installation and curing process to minimize exposure to water before the materials are fully cured.
4. Regular Maintenance: Implement regular maintenance schedules to monitor and address any signs of leaching early on, before they become significant issues.
5. Holistic Diagnosis: When diagnosing the cause of white substance leaching, take a holistic approach that considers all potential factors, including polymer re-emulsification, rather than defaulting to traditional explanations.

Conclusion

The issue of white substances leaching from pool and spa finishes is a multifaceted problem that extends beyond traditional causes like calcium and efflorescence. Polymer re-emulsification, driven by the use of modern additives in cements and grouts, plays a significant role and requires proper understanding and management. By acknowledging and addressing this phenomenon, the pool industry can move towards more durable and aesthetically pleasing finishes, ensuring long-term satisfaction for homeowners and professionals alike.