Changing the color of grout
Over the years this ceramic mosaic floor with sanded white grout darkened considerably. After many frustrating attempts to clean it, the homeowner called me and we agreed to apply epoxy-based grout colorant to the joints. The grout colorant we use is dual purpose: it not only changes the appearance of grout to a consistent color but also forms a stronger barrier to staining than regular solvent or water-based grout sealers.
Here you can see the perimeter of the floor is in progress.
After tediously painting the dark joints the homeowner was pleased with the bright white appearance of the grout.