Name one contraindication for using hot tools on hair.

The use of hot tools, such as flat irons or curling wands, can pose significant risks to hair health, especially when applied to damaged or chemically treated hair. Hair that has already been compromised due to previous chemical treatments (like coloring, perming, or relaxing) is more susceptible to heat damage. The cuticles, which are the outer protective layer of the hair, can become weakened and more porous from chemical treatments. Applying heat to such hair can lead to further damage, such as split ends, breakage, or a complete loss of hair integrity.

In contrast, while dry hair might be concerning, it doesn't automatically indicate that hot tools cannot be used; appropriate precautions may be taken. Low humidity environments do not directly impact the safety of hot tools. Thick hair types generally can withstand heat better compared to damaged hair, as they are less likely to have been previously compromised. Thus, damaged or chemically treated hair stands out as a significant contraindication for the use of hot tools.