Cast Concrete Versus Concrete-Look

Concrete became a look before most people had touched the material, so a large amount of furniture sold as concrete is a printed or coated panel. There is nothing wrong with that, but they behave completely differently and the difference is easy to detect.

What each one is

Cast concrete is cement, aggregate and water poured into a mould and cured. The colour and texture go all the way through. A 60 mm slab is 60 mm of concrete.

Concrete-look is a photograph or a textured coating on a different substrate, usually board, fibreboard or a lightweight composite. The appearance is on the surface, a fraction of a millimetre thick.

There is also a middle category, a thin concrete or mineral skim over a lightweight core, which is genuinely concrete on the outside and something else underneath.

The four tests, in order of usefulness

Weight. This is conclusive and takes one second. Concrete is dense. The Concrete Bench is a 1600 by 400 mm slab at 60 mm thick on two folded steel plates, and it weighs 84 kg. The Drum Table is 400 mm across and hollow-cast, and still weighs 22 kg. Anything of that size that one person lifts easily is not solid concrete.

The edge. On a cast piece the edge is the same material as the face, with the same aggregate visible, because it is one object. On a clad or printed panel, the edge is where the illusion is maintained by a separate operation, and it almost always shows: a mitre line, a banding, a slightly different texture, or a pattern that does not continue.

Sound. Knock it. Cast concrete gives a dull, dead thud with no resonance. A panel over a void rings or sounds hollow. On a hollow-cast piece you get something in between, which is still obviously mineral rather than board.

Temperature. Concrete has high thermal mass, so it feels cold to the hand and stays cold. A board panel comes to hand temperature quickly.

How each one fails

Cast concrete develops fine surface crazing, which is normal and cosmetic, and takes chips at corners if hit hard. Unsealed, it absorbs wine, oil and water as a stain that is genuinely difficult to remove. Sealed, it resists all three. Sealing cast concrete furniture and hairline cracks in concrete cover both.

Concrete-look fails at edges and at water. A chipped edge exposes the board core and cannot be blended, because the surface is an image. Water reaching an unsealed board edge swells it irreversibly. Neither failure is repairable.

What you give up either way

Cast concrete costs you mobility. An 84 kg bench needs two people, floor protection and a plan. It cannot be dragged, it concentrates load on small areas, and once placed it tends to stay. Moving concrete furniture and protecting floors are both relevant before delivery rather than after.

Concrete-look costs you permanence and repairability. It is lighter, cheaper, easier to move and easier to live with in an upstairs flat. It will also look obviously damaged the first time an edge takes a knock.

When each one is right

• Cast concrete when the piece is staying, when the floor can take the load, when it has to survive wine, oil and weather, and when the mass is part of the point.
• Concrete-look in a rented flat, upstairs, where the piece will move, or where the budget is the deciding constraint.

The mistake is not choosing the lighter one. It is paying cast-concrete money for a printed panel because the photographs looked the same, which is exactly what the four tests prevent.

One honest note about mass

People treat weight as proof of quality. It is proof of density, which is a different thing. A well-made lightweight piece is better engineering than a badly made heavy one. Weight only tells you which material you are holding, and that is all it is being used for here.

Reality check

• Weight is the conclusive test. Solid concrete at furniture scale is very heavy.
• The edge gives it away: same material throughout, or a seam and a banding.
• Cast concrete thuds. A panel over a void rings.
• Concrete needs sealing. A chipped look-alike edge cannot be repaired.
• Choose for the building and the use, not for which one sounds more authentic.