To preserve the look and longevity of concrete surfaces it is recommended to seal them after power washing. Otherwise, as water pools on the concrete it will seep in and cause cracks over time. Sealing the concrete turns it from a porous surface to a non-porous surface. Unsealed concrete will also collect dirt and grime faster than sealed concrete.
The sealer we use for the job depends on the type of concrete and the desired look so we always consult with the customer to determine what would work best for them.