This is a new, 1,200 square foot residential basement concrete floor with radiant heating, integrally colored "charcoal".  The homeowner wanted the concrete sealed to a matte gray "warehouse look".  The problem was, the original contractor didn't clean the concrete before sealing.  See all the paint (above).
     We stripped that sealer, and removed all of that paint, including dirt, drywall mud, and oil stains.  The above two photos show the same two areas of concrete. after stripping and cleaning.
     The next four photos (above and below) show a similar sequence in another area of the basement.  Above left you can see the white paint that was sealed over.  Above right is the same concrete after stripping the sealer and paint, and thoroughly cleaning the concrete.
     We then re-sealed the newly clean concrete with a high quality epoxy sealer (above left), in place of the low quality acrylic used by the original contractor.  Next, to achieve a "matte" appearance, and dull the gloss of the sealer, we applied a matte floor finish (above right).
     Above are two more photos of the final appearance of the floor with matte floor finish.
     The last two photos (above) show the work in progress.  Above left, you can see the existing floor sealer being stripped, with a chemical remover and rotary floor machine.  Above right, you can see the new sealer being applied.  Water-based sealers typically go down white and clear as they dry.