The best general rule when you are unsure whether a tool is safe to use on a client is to:

When unsure whether a tool is safe to use, the cosmetologist should err on the side of caution: clean and properly disinfect any nonporous, reusable tool before use, or use a new single-use item. Never use a tool that has not been disinfected since its last use on someone else. This 'when in doubt, disinfect (or replace)' habit prevents cross-contamination and protects clients. Defaulting to safe, disinfected, or fresh tools reflects the infection-control mindset that the exam consistently rewards.