To remove faucet scale, soften the deposit before scrubbing and protect the finish. Mild acid works on many mineral deposits, but it should not sit for hours on delicate surfaces.
Start with warm water and a cloth
Remove surface grime first and dry the fixture so you can see what is actual scale. Avoid steel wool and abrasive powders on chrome or decorative finishes.
Use vinegar only if the finish allows it
Dampen a cloth with white vinegar, wrap the area for a few minutes, and check it frequently. On natural stone, specialty finishes, or fixtures with restrictive care instructions, use the manufacturer-recommended product instead.
Clean the aerator separately
If flow has dropped, remove the aerator only if it comes off without force. Keep its parts in order, remove scale, and reassemble without damaging seals.
Rinse and dry when finished
Rinse away all acid or cleaner and dry the faucet. If scale comes back within days, wiping off water after use usually helps more than using a stronger cleaner.