A non breathing sealer was … When a stain isn't properly neutralized, the sealer will lose its chemical bond. In concrete containing calcium chloride, it is often necessary to wash the area several times. First, try to apply the oil based acrylic sealer after the concrete has warmed up and the sun is not shining too intensely on the surface. The spots you are seeing are due to the aggregate in the concrete. This makes the overall job look blotchy or possibly even devoid of a secondary color in those bare spots. The day they installed the concrete it was hot about 80 degrees and … To significantly reduce the risk of solvent pop and allow your concrete coating to penetrate and bond better, use the following strategies. Roller marks and their cousins, “lap lines,” are just two of those frustrating problems that can plague professional decorative installers. The overall color is just really light. When you really think about it, sealing concrete falls more into the coatings industry than the concrete industry. Would you say the dark spots are from moisture that is trapped in the concrete or the result of the sealer being applied too heavy in those spots, or should I just … Sealing concrete can be frustrating! Black stains on concrete consist of layers of dirt and oil, chemicals, ink or other substances. Problem: Concrete is dark and/or blotchy after sealer is applied Film-forming concrete sealers will darken concrete and leave a glossy shine to some extent, giving the concrete a “wet look." When clear sealer peels off an improperly cleaned stamped concrete slab, it takes the excess antiquing release with it leaving a brighter spot. The concrete stain was not neutralized in advance. Dark spots can be removed with a single washdown of water if concrete does not contain calcium chloride. And till date, there are still areas especially sidewalk and areas that are close to the wall of our house which doesn't get much of the sunlight even during the sunny days still look unevenly dark … The combination of substances become darker as layers of dirt accumulate on top of the stain. It looked like hardened cement that had dried on top and was darker in color than the rest of concrete. Either way, the aggregate dries at a slower rate than the cement it is mixed with. It’s supposed to be Two tone color (ginger and dark brown) and the contrast is hardly there at all. Depending on the concrete that was ordered you may have river gravel (smooth rocks) or crushed limestone (a rougher textured rock). It appears that best results are obtained when such discolored concrete is washed soon after the spots appear. We had a new concrete patio installed this week and after top cast was removed we noticed there was dark concrete streaks in some areas. 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