Quick answer
How is concrete coloured?
Five methods, used alone or together. Integral pigment is batched through the whole mix. Colour hardener is a dry pigment floated into the fresh surface. Acid stain reacts chemically with the cured concrete to form a permanent mineral colour. Water-based stains and dyes deposit pigment into the surface pores. Tinted sealers add colour in the coating itself. Only integral pigment and acid stain are genuinely permanent.
- Most permanent
- Integral + acid stain
- Most colour range
- Water-based stain & dye
- Works on old slabs
- Stains, dyes, tinted sealer
- Most natural variation
- Acid stain
"Stained concrete" gets used as a catch-all for half a dozen genuinely different processes with different chemistry, different permanence, and different results. Knowing which one is being proposed matters, because a quote for "staining" could mean a permanent chemical reaction with the slab or a coloured sealer that wears off in five years.
The most useful distinction is where the colour lives: through the concrete, chemically bonded into the surface, sitting in the surface pores, or in a film on top. That ordering also happens to be the durability ordering.
The five colouring methods
In order from deepest to shallowest — which is also roughly most to least permanent.
- Integral pigment
- Colour added to the whole batch at the ready-mix plant, so the concrete is coloured all the way through. Won't wear off or fade meaningfully, and a chip reveals a similar tone rather than grey. Limited to earthy, muted tones, and the colour is set before the truck leaves the plant.
- Colour hardener
- A dry pigmented powder broadcast onto fresh concrete and floated into the surface. Produces richer, more saturated colour than integral pigment and simultaneously densifies the top layer. Sits in the top few millimetres, so deep abrasion can eventually reach through it. The standard for stamped work, usually over an integral base.
- Acid stain
- A solution of metallic salts in a mild acid that reacts chemically with the free lime in cured concrete, forming a new mineral compound in the surface. Genuinely permanent — it cannot peel or wash out. Produces mottled, translucent, unpredictable colour. Limited to earth tones: browns, tans, terracottas, blue-greens, and near-blacks.
- Water-based stain and dye
- Fine pigment or dye carried into the surface pores. No chemical reaction, so results are more uniform and predictable, and the colour range is enormous — including blues, reds, and greens that acid stain can't produce. Dyes in particular are vivid but generally less UV-stable, which is why they're mostly used indoors.
- Tinted sealer
- Pigment carried in the sealer itself, forming a coloured film on the surface. The cheapest and least permanent method — it wears where traffic is heaviest and has to be reapplied to maintain appearance. Useful for refreshing tired decorative work, and a poor choice as a primary colour method.
Why acid stain looks the way it does
Acid stain is worth understanding on its own because it behaves unlike any other colouring product, and that behaviour is either exactly what you want or exactly what you don't.
It doesn't apply colour — it causes a chemical reaction. Metallic salts in a mildly acidic carrier react with calcium hydroxide in the cured concrete to form insoluble coloured compounds within the surface. The colour is literally part of the concrete afterwards, which is why it can't peel, flake, or wash away.
Because it's a reaction with the concrete, the result depends on the concrete: how it was finished, how it cured, where the paste is richer or leaner, where a trowel passed twice. Two slabs from the same truck stained with the same product on the same day will come out differently. Within a single slab, the colour varies continuously.
That's the whole appeal. Acid-stained concrete has a depth and organic variation that looks like weathered stone or aged leather, and it cannot be replicated by a uniform coating. It's also why anyone who wants a single consistent colour across a large floor should be steered toward a water-based product instead.
How a staining job actually runs
The process for acid staining an existing slab. Water-based staining follows a similar sequence without the neutralising step.
Assess and test
Check the slab for coatings, sealers, curing compounds, and contamination. Any of these block the reaction. A test patch in an inconspicuous area confirms both that the concrete will take stain and what colour it will actually produce.
Prepare the surface
Strip existing sealer or coatings, degrease, and clean thoroughly. On dense or previously sealed slabs this often means mechanical grinding to open the surface. Preparation is most of the job.
Mask and protect
Acid stain will react with anything containing lime and will damage metal, plants, and finishes. Adjacent surfaces get masked properly.
Apply the stain
Sprayed on with an acid-resistant sprayer, often worked with brushes or sponges to control mottling. Multiple colours are commonly layered for depth.
Let it react
Several hours, sometimes overnight. The colour develops progressively and looks nothing like the final result while wet.
Neutralise and rinse
The residual acid must be neutralised — usually with a baking soda or ammonia solution — and all residue removed. Sealing over unneutralised residue causes adhesion failure, and this step is the one most often rushed.
Dry, then seal
The slab must be fully dry before sealing. Then two thin coats of sealer, with a grit additive outdoors or wherever slip matters.
Choosing a method
| If you want… | Use | Why |
|---|---|---|
| Colour on an existing slab, organic and variegated | Acid stain | Permanent, translucent, and the most natural-looking result available. |
| Colour on an existing slab, uniform and specific | Water-based stain | Predictable, huge colour range, no acid handling or neutralising. |
| Bright or unusual colours indoors | Dye | Vivid and saturated. Limited UV stability makes it an interior product. |
| Colour that survives chips and deep wear | Integral pigment | Goes all the way through. Must be decided before the pour. |
| Rich colour on new decorative work | Colour hardener over integral | Depth and surface durability together. The standard on stamped work. |
| A refresh of faded decorative concrete | Accent stain plus new sealer | Restores depth for a fraction of resurfacing cost. |
Indoor and outdoor differences
Interior floors are the ideal application. No UV, no freeze-thaw, no rain, and the sealer lasts far longer — often eight to ten years rather than two or three. Dyes and vivid colours are viable indoors precisely because there's no sunlight to fade them. Polished and stained concrete floors are among the most durable and lowest-maintenance floors available.
Outdoors, three things change. UV exposure limits which products make sense — acid stain and integral colour hold up, dyes generally don't. Sealers wear far faster and need renewing every two to three years. And slip resistance becomes a live safety question, which means a matte sealer with a grit additive rather than the gloss finish that looks so good on an interior floor.
Concrete colouring questions
Related reading
Key takeaways
- Five methods: integral pigment, colour hardener, acid stain, water-based stain or dye, and tinted sealer.
- Acid stain is a permanent chemical reaction with the concrete — it can't peel or wash out.
- Because it reacts with the slab, acid stain reveals every patch, repair, and curing variation. Test first.
- Water-based stains give predictable, uniform colour and a far wider palette.
- Neutralising after acid staining is non-negotiable. Sealing over residue guarantees failure.
- Interior stained floors need resealing every 8–10 years; exterior every 2–3.
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