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Do I need to spot test Universal Cleaner first?Updated a day ago

TL;DR: Spot test Universal Cleaner in an inconspicuous area before using it on any new or unfamiliar surface. It matters most on natural stone, sealed timber and soft furnishings like carpet, upholstery and leather. Three steps, about five minutes.

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Why do I need to spot test Universal Cleaner?

Koh Universal Cleaner is a higher alkaline solution. Most hard surfaces handle it without issue, but porous and reactive materials can respond differently to an alkaline cleaner than they do to a neutral or acidic one. Natural stone such as marble, granite, travertine and limestone, sealed timber, soft furnishings such as carpet, upholstery and leather, and any vintage, hand-finished or unusual surface should be spot tested first. Raw soft metals such as zinc, copper and brass, raw aluminium, aftermarket window tints and specialty glass coatings react with alkaline cleaners and should be avoided outright rather than tested. A five-minute test catches any issue before you apply Universal Cleaner to a full surface.

✓ Spot test these first

Universal Cleaner is a higher alkaline solution. Most hard surfaces handle it without a problem, but natural stone (marble, granite, travertine, limestone), sealed timber, soft furnishings (carpet, upholstery, leather) and any vintage or hand-finished surface can react. Five minutes of testing catches it before you commit to the whole surface.

Natural stone Sealed timber Upholstery Leather Vintage finishes

⚠ Known incompatible, skip the test

Raw soft metals (zinc, copper, brass) discolour. Raw aluminium oxidises. Aftermarket window tints can peel. Specialty glass coatings such as EnduroShield can break down. These react with any alkaline cleaner, so avoid them outright rather than testing them. As a general rule, keep it off surfaces susceptible to higher alkaline solutions.

No raw soft metals No raw aluminium No aftermarket tints No EnduroShield

How do I spot test Universal Cleaner?

Spot testing Koh Universal Cleaner takes three steps and about five minutes. First, pick a hidden spot such as the back of a cabinet, the underside of a chair, the hem of upholstery, the closet floor, or any corner that will not show if something goes wrong. Second, spray a small amount of Universal Cleaner onto the hidden spot, wait a few minutes so the alkali has full contact time, then wipe clean with a Koh cloth. Third, check for colour loss, discolouration, sheen change such as matte patches on a glossy surface, etching, softening or texture change. If the area looks unchanged, you are clear to clean the full surface. If anything looks off, stop and use a cleaner made for that surface.

✓ Three-step spot test

1

Pick a hidden spot. Back of a cabinet, underside of a chair, hem of upholstery, closet floor, or any corner that will not show if something goes wrong.

2

Spray a small amount of Universal Cleaner onto the hidden spot, wait a few minutes so the alkali has full contact time, then wipe clean with a Universal Cloth.

3

Check for changes. Colour loss, discolouration, sheen change, etching, softening or texture change. If it looks unchanged, go ahead on the full surface.

What should I look for during a spot test?

During a spot test on a hidden area, watch for subtle changes that signal the surface is reacting to the alkaline formula. Colour loss or darkening is the most common sign. Sheen change shows up as matte patches on a glossy surface or shiny patches on a matte one. Etching or pitting is more common on stone. Softening, stickiness or tackiness suggests the sealant or finish is breaking down. Fabric texture change points to damage to the fibres or backing. Any discolouration on metal hardware near the test patch is a warning too. If any of these appear, stop and reach for a cleaner formulated for that surface type. If the area looks unchanged after a few minutes, go ahead and clean the full surface.

⚠ Warning signs to watch for

Changes can be subtle. Colour loss or darkening. Sheen change, so matte patches on gloss or shiny patches on matte. Etching or pitting on stone. Softening, stickiness or tackiness on a sealed surface. Fabric texture change. Any discolouration on metal hardware near the patch. If any of these show up, stop and reach for a cleaner made for that surface.

Colour change Sheen change Etching Softening Texture change
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Last reviewed: September 2026 · Koh Australia

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