Efflorescence and other types of stains rarely threaten the integrity of masonry wall systems, but they are unsightly and can be costly and burdensome to remove. Taking steps to prevent efflorescence will help ensure high-quality appearance in the finished structure and save money in the long run. Using the right cleaning method will avert further damage to the masonry. Test your knowledge of stain prevention and removal by answering the following 15 questions. The correct answers begin on page 410.