Re: help painting concrete
Sealing the paint????? would have the same result likely. Dark colors show dirt and dust. Instead of dirty paint, you will have dirty sealed paint. A non gloss finish will certainly curtail the appearance of the grime but it is still there. I suggest staining concrete with an acid stain or creating that same look with another type of stain like tru tint. The uneven, mottled look does well in hiding dirt and grime. That is why it is very common in many commercial locations like bars and restaurants. The floors look cool but hide alot of muck.
Though I digress, for your small project, you are probably changing to a lighter color and calling it a day.