How do you brighten dull and stained VCT tile?
Brightening stained tiles is usually accomplished through use of specific chemicals. For example, there are special spray buff products designed to be used with floor machines that can help bring back shine or remove stains from VCT tile. In addition to the chemical angle you can also use autoscrubbers that can remove embedded dirt and discoloration by removing the top layers of finish from your floor.
Typically the dullness and staining is embedded only in the top layers so by removing these dirty layers of finish you can apply a two to three new coats and return your floor to a much better appearance. In cases where the stain has penetrated deep in to the floor finish a chemical strip out may be required.