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What can't I use Universal Cleaner on?Updated a day ago

TL;DR: Universal Cleaner works on most household surfaces. The two to avoid are raw soft metals (aluminium, copper, brass, zinc) and aftermarket window tints or specialty glass coatings such as EnduroShield. These discolour, etch, peel or strip on contact with an alkaline cleaner. Everything else unfamiliar gets a spot test in a hidden area first.

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Why can't I use Universal Cleaner on soft metals?

Koh Universal Cleaner is a higher alkaline solution. The alkaline formulation is what cuts through cooking grease and organic matter, making it easier to clean, and it is also what makes it reactive with soft metals. Raw aluminium, copper, brass and zinc can discolour, tarnish, oxidise, etch or develop a cloudy film on contact. The reaction is chemistry, not a product fault, and any alkaline cleaner will do the same thing to those metals. Sealed, lacquered or coated versions of the same metals are usually fine to clean, but spot test a hidden area first to confirm the protective layer is still intact. For raw brass, copper or zinc, use a polish made for that metal instead.

⚠ 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 quirk. Sealed, lacquered or coated versions of those metals are usually fine, but spot test first to be sure the coating is intact.

Raw aluminium Copper Brass Zinc

Can I use Universal Cleaner on window tints and glass coatings?

No. Avoid Koh Universal Cleaner on aftermarket window tint films such as car window and privacy films, on protective window films, and on specialty glass coatings such as EnduroShield. These can peel, cloud, lift at the edges or strip when an alkaline cleaner sits on them. Factory-installed automotive tints are usually more robust than aftermarket films, but check with the manufacturer before using any alkaline cleaner on them. On coated or treated glass, the film or coating manufacturer's own cleaning guidance is the one to follow. Plain untreated glass and mirrors are fine and one of the surfaces Universal Cleaner is best on.

⚠ Avoid coated and tinted glass

Aftermarket window tints can peel or cloud. Protective window films can lift at the edges. Specialty coatings such as EnduroShield can strip. Factory-installed automotive tints are usually more robust but still worth checking with the manufacturer. Plain untreated glass and mirrors are fine.

Aftermarket tints Window films EnduroShield

What should I use instead on those surfaces?

For raw brass, copper, zinc or bare aluminium, use a polish or cleaner formulated for that specific metal rather than an alkaline all-purpose cleaner. For aftermarket window tints, protective films and specialty glass coatings such as EnduroShield, follow the film or coating manufacturer's own cleaning instructions, which usually call for plain water or a mild cleaner on a Koh glass cloth. Sealed, lacquered or powder-coated versions of those same metals are usually fine with Koh Universal Cleaner once you have spot tested a hidden area, and so is untreated glass.

✓ The straight swaps

Raw brass, copper, zinc or bare aluminium: reach for a polish made for that metal. Tinted or coated glass: follow the film or coating manufacturer's instructions, which usually means plain water or a mild cleaner on a Koh glass cloth. Sealed, lacquered or powder-coated metal and untreated glass are both fine with Universal Cleaner once spot tested.

Metal-specific polish Manufacturer guidance Plain water or a mild cleaner

What should I do if I'm not sure about a surface?

Spot test it. There are too many specialty finishes, factory coatings and vintage materials in modern homes to list every incompatible one. If a surface is unfamiliar, unusual or valuable, spray a small amount of Koh Universal Cleaner on a hidden area, wait a few minutes, wipe with a Koh cloth, and check for colour change, sheen change, etching or texture change before committing to the whole surface. Five minutes of testing beats a damaged benchtop. It is especially worth doing on natural stone, aged sealants, soft furnishings and anything the manufacturer labels a specialty finish.

✓ Spot test when you are unsure

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

Natural stone Sealed timber Specialty finishes Valuable materials
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Last reviewed: September 2026 · Koh Australia

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