Concrete Color: Using Black Pigments In Ready Mix
Black is widely used in the concrete industry. It can be mixed to darken other pigments, and it can be used alone to make light grays, dark grays or straight black.
by David Thompson
When using a black pigment to integrally color concrete, black is black and that's that.
: Absolutely false.
Black is widely used in the concrete industry. It can be mixed to darken other pigments, and it can be used alone to make light grays, dark grays or straight black.
It's commonly used in driveways — and especially in gas stations — because it hides oil stains and grime. It's sometimes used in highways and runways because black absorbs heat and discourages ice. In decorative concrete, integral black with a silver release is a popular combination.
"Black is easily one of our top five colors out of our 40 standard colors," says Nick Paris, vice president of marketing for Davis Colors, the Los Angeles-based color manufacturer.
Black pigment for integral coloring comes in two forms, one made from iron oxide and one made from carbon.
Iron-oxide black is the most commonly used in black concrete, Paris says. "Most people find it black enough," he says. "But occasionally someone wants a super-dark black, and then we recommend carbon black. With carbon black it's possible to get a jet-black, like a bowling-ball black. Iron oxide just won't get that black."
Carbon creates the blacker black. It's also more economical. But it can affect air entrainment, and it can weather out of concrete over time. So just any black won't necessarily do.
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