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What are Diamond Sponges made of and can I recycle them?Updated 16 days ago

TL;DR: Diamond Sponges are made from high-density PU foam with a silica alumina abrasive coating. Not recyclable in most kerbside bins due to bonded mixed materials. Reuse for dirtier tasks when worn, then place in general waste.

Last reviewed: April 2026

Koh Diamond Sponge technical detail
Koh Diamond Sponge lifestyle

What are Diamond Sponges made of?

Diamond Sponge has two parts. The core is a high-density polyurethane (PU) foam block that gives it structure and springy feel. The outer coating is a silica alumina abrasive film bonded to the foam. That grit is the "diamond" that does the heavy lifting on hard water marks, soap scum, and baked-on build-up.

Core

High-density polyurethane (PU) foam block. Firm, springy, and holds its shape as you scrub. The foam carries the abrasive coating to the surface.

PU foam High density

Coating

Silica alumina abrasive film bonded onto the foam. This is the gritty surface that grinds through hard water stains, soap scum, and baked-on residue where softer sponges give up.

Silica alumina Abrasive film

Can I recycle Diamond Sponges?

No. The bonded abrasive film can't be separated from the PU foam at standard recycling facilities, and mixed-material items get rejected by kerbside streams. Diamond Sponges aren't suitable for compost, soft-plastic drop-off, or TerraCycle programs either. Best option is to reuse the sponge for dirtier jobs as it wears down, then place in general waste.

⚠ Not kerbside recyclable

The abrasive coating is bonded to the foam core and can't be separated at standard facilities. Mixed-material items contaminate kerbside recycling and get sent straight to landfill.

Mixed materials Not kerbside

⚠ Not compost or soft plastics

PU foam doesn't biodegrade, so compost and green waste are out. The silica alumina grit means soft-plastic drop-off and TerraCycle programs can't take them either.

Not compost Not soft plastics

What should I do with worn Diamond Sponges?

Downgrade worn Diamond Sponges to dirtier tasks first. Once it's too smooth for bathroom tile or kitchen surfaces, send it out to scrub BBQ grills, garden pots, tool handles, or boot soles. When the abrasive coating is gone or the foam starts breaking apart, wrap the remains and put it in household rubbish.

✓ Reuse for dirtier jobs

When the sponge is too smooth for bathroom tile or cooktops, move it outdoors. Scrubs BBQ grills, garden pots, muddy tool handles, outdoor furniture, and boot soles to stretch the lifespan.

BBQ grills Garden pots Tool handles

Final disposal

When the coating is fully worn smooth or the foam starts crumbling apart, wrap the remains in a scrap of paper or used packaging and place in household general waste.

Wrap + bin General waste
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Grab a 4-pack

Diamond Sponges handle the tough jobs regular cloths and sponges can't touch. High-density PU foam with a silica alumina coating.

Koh Universal Cleaner

Pair with Universal Cleaner

Pair Diamond Sponges with Universal Cleaner for lifting power on stubborn stains.

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