What surfaces should I avoid using Universal Cleaner on?Updated 5 hours ago
TL;DR: Universal Cleaner is safe for most household surfaces, but avoid raw soft metals (aluminium, copper, brass, zinc) and aftermarket window tints or specialty glass coatings (factory-applied or aftermarket easy-clean coatings such as ShowerGuard, Diamon-Fusion, ClearShield, EnduroShield, or similar hydrophobic glass treatments). These can discolour, etch, or peel when exposed to alkaline cleaners. When in doubt, spot test a hidden area first.
Why can't I use Universal Cleaner on soft metals?
⚠ 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.
Can I use Universal Cleaner on window tints and glass coatings?
⚠ Avoid on coated glass
Aftermarket window tints can peel or cloud. Protective window films can lift at the edges. Easy-clean glass coatings (ShowerGuard, Diamon-Fusion, ClearShield, EnduroShield, or similar hydrophobic glass treatments) can strip. Factory-installed automotive tints are usually more robust but still worth checking with the manufacturer before use.
What should I do if I'm not sure about a 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 as a specialty finish by the manufacturer.

Pairs a box of Universal Cleaner with Atomiser Spray Bottle and Universal Cloths. Everything you need to start.
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Last reviewed: May 2026 · Koh UK


