Grouting fills the gaps between tiles, creating a white or white light-gray grid. The thick mortar can become stained over time, especially if it is not sealed. Food and grease are likely offenders for darkening kitchen grout, while soap scum can filthy toilet grout. If your grout has turned dark, then a thorough brushing with the ideal cleanser and applying a bleaching agent can lighten it again, leaving it good as new.
Sweep and mop if cleaning floor grout. Wipe down wall grout with soapy water and a sponge. Wash well.
Mix degreasing cleanser with water in a bucket according to package instructions and sponge it on the grout. If the degreaser comes in a spray bottle, then spray it straight onto the grout. Leave on for 15 minutes or as recommended on the bottle.
Dip a scrub brush with nylon bristles into the bucket or spray on the seams with a different coat of spray degreaser.
Scrub the grout vigorously to remove as much dirt and grease as possible. Wash the degreaser away as you work.
Treat resistant dark spots with a homemade foaming cleanser. Combine 1/4 cup white vinegar, 1/2 cup baking soda and 7 cups water in a large spray bottle. Shake to mix. Soak the grout with the mixture and allow it to set for 15 minutes. Scrub it with the bristle brush or wipe it away.
Employ a professional to steam clean your grout in case none of the aforementioned steps lighten it into your satisfaction. Steam goes deep into the grout to get rid of stubborn discoloration. Ask the professional to seal your grout or teach you how you can seal it after cleaning to avoid future darkening.