I recently laid a brick step as a transition from one part of an old patio, to a new, lower level patio. Both the old and new patios were stained and sealed with a xylene base sealer about 3 months before I built the step. Now certain areas of the lower concrete surface have developed white stains up against the brick step. I do not think the clouding is coming from moisture seeping in from below, as we did put a vapor barrier under the new slab. I am assuming that it is efflourescence from the brick, because it started immediately after we laid the step.
It looks as though I will have to strip the sealer from the effected patio surface and re-seal it. How can I tell when the brick step has stopped the staining? I would hate to go through the effort of re-sealing the patio, just to have it cloud up again. Is there any way to salvage the existing sealer instead of stripping it and starting from scratch?
TIA for help.