The following pictures are of a decorative concrete patio that had been neglected for a couple of years. The owner wanted to know what the options were to refresh the look. After a good thorough scrubbing with a citrus based concrete cleaner the patio was still a little milky in spots. This is called "blushing" and is a result of moisture being trapped between the sealer and the concrete substrate. This can happen in many ways: sprinklers watering the patio, poor drainage, gutters and down spouts releasing on the patio are just a few examples. If this was new construction the most common culprit is a sealer being applied to a patio that was recently washed and did not dry out before a sealer was applied. After washing a concrete slab the surface will appear dry quickly, however there is still moisture trapped in the concrete that will make its way to the surface. Sun and heat will draw this moisture up and if a sealer is applied too soon it can cause the milky appearance common with blushing. One way to correct this issue is to do a solvent wipe. A solvent such as xylene can be spread on the surface and light scrubbed with a stiff brush; this will re-emulsify the resins and let the trapped moisture leave the surface. This is sometimes enough to bring a sealer back to life, sometimes after doing this another application of sealer will be needed to even out the surface and provide a more uniform appearance. These steps are for solvent based sealers only.
Picture 1 - Patio before any steps were taken
Picture 2 - Patio in the process of a solvent wipe
Picture 3 - Final product after a very light additional coat of BRS-25 was applied