What is a common characteristic of two-component putty?

A common characteristic of two-component putty is that it requires a hardener. This type of putty typically consists of two components: the base material and a hardener or curing agent. When mixed together, these components initiate a chemical reaction that causes the putty to cure and harden over time, creating a strong and durable bond. This characteristic is vital in applications where strength and durability are required, such as in automotive repairs and refinishing.

In contrast, the other options do not accurately describe two-component putty. For instance, it is not water-soluble; rather, it is designed to resist moisture once cured. Additionally, it cannot be effectively used without mixing since the hardening process depends on the correct ratio and combination of both components. Lastly, while putties can be used in various applications, they are not limited to wet applications only, as they are often used in dry environments where their strength is needed.