You can color concrete with acrylic paint by mixing it into the wet mix. Acrylic paint can be a cheap way to color concrete crafts. The same goes for using latex paint for coloring concrete. I made these DIY Concrete Pillar Candleholders using white cement mix and the green was acrylic paint.
Cleansing — For mild discoloration, repeatedly flushing the hardened concrete surface with hot water, then scrubbing with a stiff brush, can reduce or remove discolored blotches. Acid treatment — If the discoloration is more severe, a mild acid solution of 1-3% muriatic acid to water can help remove the discoloration.
Over time, even the most beautiful and best done stamped concrete can lose its color and begin to look faded and unattractive. Recoloring it with concrete colors can quickly revive the look of stamped concrete. There are few ways to approach recoloring concrete based on your final outcome desired.
Discoloration Caused by Efflorescence
Efflorescence is water soluble so it often disappears when rinsed away with water. The efflorescence however really isn't gone and will re-form again quickly after. The best way to remove efflorescence is with an efflorescence cleaner, such as the Foundation Armor ER100.
A small amount of acid added to the water will pull the stain out of the concrete without etching the concrete surface. In essence, the acidic solution reverses the reaction, allowing you to pull the color back out of the concrete.
Why is my concrete turning white? Efflorescence is a white salty residue caused when too much moisture is moving through the concrete. As the concrete dries and its moisture rises upwards through the slab, it brings salts within the concrete to the surface as well.
Fresh concrete is always much darker than when it is fully cured and dry. Even uncolored concrete. Wait at least 7 to 10 days until the new concrete has hardened and dried. If the concrete is on a wet subgrade or there's underground water, it may stay dark for as long as it's wet.
Sealers, particularly solvent-based sealers, will darken concrete. If unevenly applied, it will create light areas where there is less sealer, and darker areas where there's more. If applied by sprayer, it may appear like “stripes”. Uneven roller application may leave darkened roller marks.
Vinegar and Baking Soda
Simply fill a spray bottle with equal parts water and vinegar (or water and baking soda), and add a little bit of liquid dish detergent. Spray the mixture on your concrete surface and let it sit for about 30 minutes. Then scrub and rinse your concrete.
White vinegar and a little scrubbing with a brush is a very effective, eco-friendly way to remove rust stains from concrete—even those that are decades old. Pour the white vinegar directly onto the stain, allow the liquid to penetrate the area for 20 minutes, and scrub with a stiff-bristled brush.
Use full-strength vinegar if you need to remove heavily soiled concrete and let it sit for 30 minutes before rinsing it off with water. You can even mix baking soda with vinegar to remove grease and deep stains.
The small dye particles fill the pores of the concrete and are very hard to remove, making dyes nearly as permanent as stains.
Pressure washing is one of the fastest, most effective ways to get your concrete white again. Concrete can change color over time due to pollen, algae, or dirt buildup, but a good pressure wash can easily remove dirt and stains and make your concrete look new again.
To lighten stamped concrete after using a color release powder or liquid, you must first strip the sealant with a chemical stripper designed for this purpose. Scrub the stripped concrete with a stiff-bristled brush to remove as much of the color as you can.
Concrete discoloration is not a rare event
The use of too much or not enough water. The use of calcium chloride. Improper concrete laying techniques. Outside temperatures.
How to Colour Concrete. There are two main ways to colour concrete. The first uses a dry pigment that is brushed across concrete once it has been laid. The second uses liquid or dry pigment that is mixed into the concrete before it is poured.
Although the bulk of the hydration process takes place in the hours and days immediately after the pour, concrete needs 28 days to fully dry. While the slab will harden and lighten in color before 28 days, don't be fooled into thinking it's done hydrating.
Heavy coats of sealer, or a buildup of sealer applied numerous times over the years, will cause moisture to become entrapped under the sealer and, in time, the sealer loses adhesion from the concrete.
Solution: To fix you will need to remove the sealer with a concrete or paver sealer stripper. Trapped moisture under the sealer is the most common reason that the sealer has turned white. This happens to sealers that are not breathable or over-applied.
Etching – Vinegar's ability to dissolve CaCO3 will dull your marble, travertine, concrete and terrazzo surfaces. It may “clean” the surface but it is also dissolving pits into the finish and effectively dulling it.
Concrete stains can be a great option for changing the color of your concrete without having to completely resurface it. EasyTint solvent-based tinted sealer is a semi-transparent stain that can add a new color to your already stained concrete.
There are two ways you can take a dark stain and make the final shade lighter. First option would be to dilute the acid stain itself. Second option would be to wash the stain off earlier in the process. In addition a second test patch should be done before completing the project.