Fill a bucket with 1 tablespoon of dish washing soap and add water. Dip a large sponge in the bucket and scrub the brick until clean. Use a toothbrush to gently scrub the mortar between the brick as well, being careful not to scrape the mortar and cause it to come loose. Rinse the brick with clean water and allow it to dry completely.
Apply a thick coat of paver stripper to the surface of the brick using a paint roller. You can purchase paver stripper from your local paving supplier. Allow the stripper to work for 10 to 20 minutes.
Wash the stripper off of the bricks with clean water. The paver stripper will have removed all shine from the bricks, as well as any yellowing caused by the sealant.
Allow the bricks to dry for one to two days to make sure that the brick is free of moisture. Wait two days after any rain storms as well.
Use a roller to apply a new, thin coat of sealant to the surface of the bricks. Allow it to dry, then apply a second coat.