Grout is a mixture of cement, colour and sand, and it is used to adhere tiles to a surface. Although traditional grout colours are common, designer colours are available, such as charcoal and black. Dirt and grime tend to collect in the pores of grout, especially unsealed grout. Although black grout does not show stains as much as lighter coloured grout, regular cleaning is still essential to black grout. Remove the dirt and gunk from black coloured grout with solutions that are effective at maintaining the colour of the grout.
Pour oxygen bleach into a spray bottle. Oxygen bleach is safe for all types of grout, and the free oxygen ions in the bleach dissolve the stain molecules in grout.
Spray the oxygen bleach directly onto the black grout. Allow the grout to absorb the oxygen bleach for an hour. If the grout becomes dry, spray more oxygen bleach onto the grout.
Scrub the grout lightly with a bristle brush. The bristle brush will remove the dirt and residue from the grout.
Fill a cleaning bucket with warm water. Dip a sponge mop into the warm water.
Mop the grout with the warm water. Allow the grout to air dry.
Clean black grout with heavy-duty cleaner, instead of oxygen bleach. Apply masonry sealer to black grout, to prevent future stains.
Do not use chlorine bleach on black grout, as the grout may become discoloured.