Which of the following is not a focus of SSPC TU 11?

SSPC TU 11 is focused on various aspects of surface preparation and application of coatings, particularly for steel structures in the marine environment. It addresses several key areas relevant to ensuring high-quality paint application.

The guidance for using optically active pigments is part of the document as it helps inspectors understand how these pigments affect the performance and visibility of coatings. The applicable environmental conditions are also covered in SSPC TU 11, as proper environmental considerations are vital to achieving optimal coating performance.

Oil contamination testing is another important aspect that SSPC TU 11 addresses, as surface cleanliness is crucial for good coating adhesion and performance. This includes procedures to identify and evaluate contamination that could compromise the integrity of the coating system.

In contrast, while methods for assessing spray application quality are crucial in general paint application practices, they are not specifically a focus of SSPC TU 11. The emphasis of the document leans more towards the overall principles and practices of surface preparation rather than detailed methodologies to evaluate the quality of spray applications. Thus, identifying that this particular aspect of spray application quality is not directly covered in SSPC TU 11 clarifies why it is the correct answer.