Existing concrete floor · colour and renovation
If you want to colour a concrete floor afterwards, it starts with the condition of the floor. Incorporating pigment into fresh concrete is different from treating a hardened floor. Another colour is sometimes possible, but the result and preparation differ depending on the method.
Why can’t you simply re-polish pigment?
With a new polished floor, colour can be incorporated during the plastic phase. In a broadcast top layer, pigment, cement and suitable aggregates are incorporated into the surface during finishing. The concrete is still workable at that stage.
An existing hardened floor no longer has that possibility. Distributing pigment over the floor afterwards and working again with a power trowel does not produce the same build-up. For a colour change, a treatment must therefore be chosen that is suitable for the already hardened substrate.
Colour throughout the entire concrete mass is something arranged during the composition of new concrete. You can read more about that at concrete coloured throughout.
First determine which colour result you are looking for.
Do you want to deepen the existing shade a little, reduce disturbing colour differences, or completely change the colour of the floor? These are different questions. A transparent treatment can reveal nuances, while an opaque layer largely covers the natural concrete appearance.
A test area prevents wrong expectations.
View a test treatment in daylight and the room’s lighting. Assess colour, gloss and pattern only after the prescribed drying. A wet surface can temporarily appear much darker than the final result.
What options are there for an existing floor?
| Treatment | What changes? |
|---|---|
| Cleaning and appropriate maintenance | Dirt or residues can distort the colour appearance. Good cleaning is sometimes the first step to see the actual condition. |
| Wax or colour-enhancing protection | Depending on the product, it can influence gloss and shade, but does not create an arbitrary new base colour. |
| Specialist colour treatment | Can give a different shade on a suitable substrate. Absorption, colour fastness and protection must be assessed product-specifically. |
| Opaque coating | Gives a different visible finishing layer. The natural concrete appearance changes and the substrate must be suitably prepared. |
What does wax do to the colour of concrete?
A suitable wax can influence the gloss and colour appearance. Some floors therefore appear deeper or darker in shade. That effect is not a substitute for pigment added during casting or finishing. A light floor will not automatically become an even anthracite floor through wax.
An existing protective layer is also important. Combining products without knowing what is already on the floor can produce an undesirable result. Read more about waxing and polishing a concrete floor.
The blue stone imitation in this childcare centre occurred during the execution of the new floor. That is a different approach than treating existing concrete afterwards.
When does a coating come into consideration?
If you are looking for a completely different, opaque colour, a suitable coating system can be an option. Consider, for example, an epoxy or other resin-bound system that suits the space and load. The concrete then becomes the substrate for a separate finish.
The substrate must be assessed for cohesion, contamination, moisture and existing layers, among other things. Cracks and joints require appropriate detailing. A layer of paint is not a general solution for moisture problems or movement in the floor.
A coating also has its own maintenance and repair method. Discuss beforehand whether the chosen appearance matches your expectations and how the space is used daily.
Eliminating colour differences or stains
Not every colour difference is contamination. Concrete can have natural nuances due to processing, drying and use. Also, a remaining concrete curing layer or previous treatment can influence the appearance. Therefore, it is useful to first assess the cause.
A dark stain sometimes remains visible through a transparent treatment. A new colour layer can actually accentuate differences if the surface absorbs unevenly. So do not immediately start recolouring before it is clear what result is achievable.
What information do we need?
Send overview photos and detail photos in normal daylight. Specify the age of the floor, previously used products, and exactly what you want to change. Also indicate whether the floor is indoors or outdoors and if there are problems with moisture, dusting, or delaminating layers.
With that information, we can discuss the next step: thorough cleaning, assess the existing protection or investigate a specialised colour finish. Not every desire requires the same intervention.
Frequently asked questions
Can a grey concrete floor be made black afterwards?
It is not a simple matter of re-polishing pigment in. Whether a suitable colour treatment or opaque layer is possible depends on the substrate and the desired result. First have a test area and system choice assessed.
Do stains become invisible through a new colour?
That is not guaranteed. Transparent treatments can make existing differences visible. The cause and depth of the stain must first be examined.
Should I first remove the old wax or concrete curing?
That depends on the existing layer and the new system. Some treatments require a clean, sufficiently open substrate. The product instructions determine the preparation.
Colouring a concrete floor afterwards: possibilities and limitations