Which material is known for being very elastic, especially when placed in water?

Nylon is recognized for its excellent elasticity, particularly when it comes into contact with water. As a synthetic polymer, nylon has a unique molecular structure that allows it to stretch and return to its original shape without losing its integrity. This characteristic makes it suitable for various applications, including textiles and optical frames.

When nylon is submerged in water, it can absorb moisture, which enhances its ability to stretch and compress while maintaining resilience and strength. This is particularly advantageous for opticians when selecting materials for eyewear, as the elasticity helps in fitting and comfort.

In contrast, other materials listed may not exhibit the same level of elasticity or response to moisture. For example, polyamide is a category that includes nylon but does not specifically address its water-related elasticity. Carbon filters are unrelated to the discussion of elastic materials, and cellulose acetate, while used in eyewear, does not share the same elasticity characteristics when exposed to water. Understanding the unique properties of nylon, especially its behavior in wet conditions, is crucial for making informed choices in opticianry.