What is the minimum number of strands recommended for a metallic test?

The correct answer is based on industry standards and safety protocols for conducting metallic tests on hair. A recommended minimum of 20 strands ensures a more accurate assessment of the hair's condition and potential reactions to chemical processes, particularly when determining the presence of metallic salts.

Using at least this number of strands allows for a reliable sample size that can help identify metal buildup which could lead to adverse reactions during subsequent chemical treatments, like coloring or perming. A larger sample also aids in achieving a consistent and representative result, which is crucial for making informed decisions about hair treatment.

Opting for fewer strands may not provide a comprehensive understanding of the hair's overall condition, potentially leading to erroneous conclusions and unsafe practices. Therefore, adhering to the recommendation of 20 strands is both a precautionary and professional practice in the hairstyling industry.