Danilo’s experience with MMA basecoat yellowing in acrylic bathtub repairs is not uncommon, and it highlights a critical aspect of the repair process that sometimes goes overlooked—the application of a protective clear topcoat. This issue underscores the necessity of adhering to the complete MMA system process to prevent discoloration and ensure the longevity of repairs.

Understanding the Yellowing Issue

The yellowing of the MMA basecoat, as reported by Danilo, primarily occurs when the protective clear topcoat is either not applied or is removed through excessive sanding and buffing. This protective layer is crucial for sealing the basecoat, shielding it from various factors that can lead to yellowing such as sunlight exposure, and contact with soaps, cleaners, and hard water.

The Role of Protective Clear Topcoat

The protective clear topcoat is designed to seal the basecoat, preserving its color and preventing the absorption of materials that could lead to discoloration. It’s an integral part of the MMA system, providing a barrier against environmental factors and ensuring that the repair remains durable and aesthetically pleasing over time.

Preventive Measures and Solutions

1. Use of Clear Topcoat: Ensure that every repair, without exception, includes the application of the clear topcoat specified for the MMA system. This step is vital for the repair’s durability and appearance.
2. Proper Application: Avoid excessive sanding and buffing that could potentially remove the clear topcoat. The objective is to maintain this protective layer intact to safeguard the basecoat underneath.
3. Storage and Exposure: If a bathtub or spa is stored outside or exposed to the elements, it’s more susceptible to yellowing. Protect these items from direct sunlight and harsh conditions by using appropriate covers or storing them indoors.
4. Quality Control: Rob Clos suggests that production and quality control departments incorporate the clear topcoat into their processes, emphasizing its importance for the longevity of repairs.
5. Avoiding Contamination: Ensure that the MMA and Quick Glaze components are used as intended without contamination from other products. Use only MTP brand components for consistency and compatibility.
6. Handling Moisture and Oil in Air Lines: Utilize desiccant filter towers or in-line desiccant air filters to remove moisture and oil from compressed air lines. This step prevents fisheyes and other imperfections during the spraying process.

Conclusion

The yellowing of the MMA basecoat can be effectively prevented by adhering to the prescribed repair process, which includes the crucial application of the clear topcoat. Multi-Tech’s advice sheds light on the importance of this step, as well as the need for proper handling of repair materials and equipment to maintain the quality and appearance of acrylic bathtub repairs. By following these guidelines, repair technicians can ensure their repairs remain pristine and durable, reflecting the high standards of quality expected in the industry.