Colour variation in polished concrete is normal in the material and unacceptable in the delivery. The job is to know which variation comes from the mix, which from the finish, and which was created on site.

Sources

Source	Look	Fixable?
Different pours	Panel-to-panel tone shift	Only by blending or accepting
Aggregate exposure	Speckled patches, lighter zones	Yes, by evening the cut depth
Densifier uneven	Dark rings, streaks	Yes, by re-wetting and repolishing
Moisture	Broad dark areas	Only after moisture is resolved
Cure compound residue	Blotchy haze	Yes, strip and re-hone

Where variation is created on site

• Inconsistent cut depth between operators or machines.
• Densifier applied in sun, or in patches, or at different rates.
• Stopping the machine in one spot and burning a ring.
• Polishing a floor at different moisture states across a day.

Blending techniques

For panel shifts, feather the boundary over 1-2 m with a slightly coarser pass, then re-polish. This softens the line without changing the tone. For aggregate patches, a light extra cut on the lighter zone evens exposure; check every 200 mm because over-cutting creates the opposite problem.

What to promise

Polished concrete is a variegated material. Show the client a sample panel made from their actual mix, in their actual light, before work starts. A signed sample prevents the conversation where the client expects uniform colour and the floor delivers geology.

Document the sequence and the densifier rate per 100 m2. When variation appears, that record tells you whether it was the material or the crew, and it decides who pays.