The Stain Library

Material

Composite sink

Stone particles in acrylic resin: harder than acrylic, softer than ceramic, and prone to a dull residue film rather than to staining.

  • SurfaceNon porous
  • WashingSpot only
  • Colour run riskLow
  • Reviewed7 September 2026

What composite sink can and cannot take

  • Heat Use with care
  • Water and soaking Tolerates it
  • Acids, including vinegar Use with care
  • Strong alkalis Use with care
  • Solvents Use with care
  • Chlorine bleach Use with care
  • Abrasives Use with care

General rules for composite sink

Warm soapy water and a soft cloth deals with a fresh milk mark, because the resin surface is effectively non porous.

The distinctive problem with composite sinks is film rather than stains. Detergent, hard water and food residue build a dull haze, particularly on black and dark grey sinks, and that is what people mistake for staining.

Rinse and dry the sink after cleaning it. That single habit does more for a composite sink than any product.

Check the label

A composite sink is stone particles bound in acrylic resin, so it is harder than acrylic and softer than ceramic. It is stain resistant rather than stain proof, and the matt surface holds a residue film that shows on dark sinks as a dull haze rather than as a mark.

Stains on composite sink

A composite sink is crushed granite or quartz bound in an acrylic resin and moulded.

It is stain resistant, not stain proof

The resin binder is non porous but the surface is matt and textured, so residue clings to it. Left to dry, milk leaves a film rather than a stain.

The film is the real complaint

On black and dark sinks, a build up of detergent, limescale and food residue reads as a chalky haze. That is why so much composite sink advice is about rinsing and drying rather than about cleaning.

It is harder than acrylic

So a soft nylon brush is acceptable where it would not be on an acrylic bath. Metal scourers still scratch it.

Very hot pans mark it

The resin binder is thermoplastic and a pan straight off the hob can leave a permanent dull patch.

Sources

What we checked and when. Where a manufacturer instruction disagrees with anything here, follow the manufacturer.

  1. Melamine dinnerware and staining, G.E.T. manufacturer

    Melamine manufacturer guidance that staining is caused by food left to dry on the surface and by protein and hard water minerals building up, that an oxygen releasing soak or an overnight soak in warm water with dishwashing granules removes the stains, that a non abrasive pad is used afterwards, and that bleach, green scouring pads, steel wool and metal scourers must not be used because they dull and scratch the surface.

    Checked 7 September 2026

  2. Bathroom care guide, Carryduff Designs manufacturer

    UK bathroom supplier guidance that acrylic is softer than china and scratches, that scouring products are not recommended, that chemicals including nail varnish remover, household bleach, perfume and strong disinfectant must never be used on acrylic, that warm soapy water or a mild cream cleaner is the correct clean, that mild limescale removers are acceptable occasionally, that bleach must not go in a cistern, and that cleaners must never be mixed because they give off poisonous gas.

    Checked 7 September 2026

  3. Norovirus: what to do and how to stop the spread, UK Health Security Agency authority

    UK public health guidance establishing that illness related vomit can carry norovirus, that contaminated laundry should be washed with normal powder at 60 C where the care label permits, and that compatible hard surfaces should be disinfected with a bleach based product.

    Checked 7 September 2026