What can't I use Universal Cleaner on?Updated 9 hours ago

Universal Cleaner is alkaline (pH 12.5), which is strong enough to cut through grease but reactive with soft metals. Raw aluminium, copper, brass, and zinc can discolour, tarnish, oxidise, or etch on contact. The reaction is chemical, not a cleaning product defect. Any alkaline cleaner will do the same thing.

⚠ Avoid raw soft metals

Raw aluminium oxidises or pits. Copper and brass tarnish or discolour. Zinc can develop a cloudy film. These are chemical reactions with any alkaline cleaner, not a Koh-specific issue. Sealed or coated versions of these metals are usually fine but spot test to be sure.

No. Avoid Universal Cleaner on aftermarket window tint films (car windows, privacy films), protective window films, and specialty glass coatings like EnduroShield. These coatings can peel, cloud, or strip when exposed to alkaline cleaners. Always follow the manufacturer's cleaning guidelines for coated glass.

⚠ Avoid on coated glass

Aftermarket window tints can peel or cloud. Protective window films can lift at the edges. Specialty coatings like EnduroShield can strip. Factory-installed automotive tints are usually more robust but still worth checking with the manufacturer before use.

Spot test. There are too many specialty finishes, manufacturing coatings, and vintage materials in modern homes to list every incompatible surface. If a surface is unfamiliar, unusual, or valuable, spray a small amount of Universal Cleaner on a hidden area, wait a few minutes, wipe, and check for colour, sheen, or texture change before committing to the full surface.

✓ Spot test when unsure

Pick a hidden corner, spray a small amount, wait a few minutes, wipe clean, and check for any change. Five minutes of testing beats a damaged surface. Especially worth doing on natural stone, aged sealants, soft furnishings, and anything marked "specialty finish" by the manufacturer.