Maintained or Weathered
Exposure to sunlight, changing temperatures and accumulation of vegetation changes the appearance of pavers. Some people prefer the weathered look, and some paver designs are enhanced by moss, algae and lichen. Other people prefer the new, washed look. Many people resent digging out pavers to extract weeds from the seams, but may not like the idea of spraying herbicides to get rid of the vegetation. For the clean look, and no herbicides, seal.
Pavers can be pressure washed to achieve a clean, new look. Pressure washing is part of standard maintenance for unsealed pavers. Before pressure-washing, pavers can be removed one at a time to remove opportunistic vegetation, then the pavers can be put back. If you want to avoid this periodic maintenance, you can use a sealant. Sealant retards weathering and prevents opportunistic vegetation. It also gives the pavers a shiny, wet-looking surface.
Before sealing, pressure wash. Whatever grit falls into the cracks firms up the pavers, but the rest of the dust and grit will mix with your sealant, dulling it. Let the pavers dry, sweep up and apply. Most sealants can be applied using either a paint spray gun or a paint roller. Some people brush on the sealant, but this is not recommended because brushes pick up debris from the seams between the pavers.
Paver sealants come in two categories: coatings and impregnators. Coating sealants sit on the surface of the pavers, and can be removed in the future, leaving the pavers much as they began. Impregnators, on the other hand, percolate into and bond with the microsurfaces of the pavers, changing the surface characteristics. Sealants also come with color enhancers to brighten the natural surfaces of the pavers. Sealants are available with flat or shiny finishes.