[Evans, Marv]

I also have colored, stamped concrete and need to reseal. The color in the stamping on the garage apron has pretty much disappeared due to weathering & not being resealed for a long time. So I'm looking for a quality sealer and will be checking this thread. The stamping under the patio & portico covers are OK.
"rnln", the white stuff you describe may be efflorescence. It's a white residue that probably needs to be treated with something like vinegar, scrubbed and finished up with a (neutralizing) solution of baking soda in water. After rinsing & drying, it can be resealed.