Hardening and Non-Hardening are two types of what?

• A. Seals
• B. Gaskets
• C. Sealers
• D. Lubricants

Answer: (C)

Hardening and non-hardening describe how sealing compounds behave after they’re applied. Sealing compounds, or sealers, are used to close gaps and prevent leaks between mating surfaces. Some sealers cure and become a hard solid, forming a permanent, rigid seal that resists movement and stress. Others don’t cure into a hard substance; they stay flexible or tacky, which allows for movement, thermal expansion, and easier disassembly when maintenance is needed. This distinction is exactly what the terms hardening and non-hardening are capturing, which is why sealers is the best fit.

Seals are mechanical devices that press against surfaces to block leaks, gaskets are pre-formed shapes used in joints, and lubricants reduce friction and wear—none of these describe the curing behavior of sealing compounds.