ROKA

Why Our Concrete Changes Colour When We Hone It

By ROKA Studio

Seven ROKA concrete sample colours in pairs, salt and pepper finish on the top row and cream finish on the bottom row

We were casting sample tablets this week. Straight out of the mould, they looked like every other sample online. Full colour. Flat. Not a grain of sand in sight.

Then we honed one.

The colour moved. Lighter, softer, speckled. Same tablet, same mix, and it looked like a different material.

So which is the real finish? Both, as it turns out. Which is why we now offer two.

What's happening at the surface?

We cast face down, into a smooth mould. The finest part of the mix, the cement paste, settles against the mould face. It sets as a thin, dense skin, almost all paste and hardly any sand.

Pigment colours that paste. It doesn't colour the sand. So the skin carries the colour at full strength, and everything below it is paste and sand together.

Why do most samples online show no sand?

Because most of them are cream finish. Demould, seal, done. It's a proper finish, the colour is at its deepest, and it makes for a very good-looking sample.

It just isn't the only way to finish a worktop.

What does honing actually do?

We work over the surface with diamond pads, coarse to fine, up to 800 grit. The coarse pads take the skin off and open up the sand. The fine ones bring the surface back to smooth, with a soft sheen.

What's left is the mix as it really is, all the way through. A fine speckle of sand in coloured paste, which is why it gets called salt and pepper.

So which one is better?

Neither. They're good at different things.

Cream wins on colour and flatness. Salt and pepper wins on wear, because a scratch has no skin to cut through, so it blends in. We've set out the choice properly on our finishes page.

Why does this matter when you pick a sample?

A sample only tells the truth if it's made the way your worktop will be. Same mix, same finish, same seal. Choose from a cream sample and receive a honed worktop, and you'd be right to feel short-changed.

So every ROKA sample now goes out in both finishes, labelled. Straight out of the mould is a finish. It's just not the only one.

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