Cleaning grout often proves the foremost challenge in maintaining tile surfaces since dirty water gets pushed into the grout lines with each mopping.

There are basically two types of grouts: Cementious and epoxy.

Cementious grout is cement-like, while epoxy grout is plastic-like.

You will rarely encounter epoxy grout, also called stainless, due to its high price tag.

It's most commonly found in commercial buildings and used instead of unsanded grout when the joint between tiles are very small, such as between marble tiles.

Epoxy grout cleans well, but can't be sealed.

Most chemicals fail to work in cleaning the cementious grout because the stains are absorbed by the grout.

Chemicals with oxygen bleach work well, since they give it some bleaching action, so long as adequate dwell time is allowed.

Also remember to use proper tools and water pressure: 800-1200 PSI.

To treat extremely "blotchy" grout that doesn't respond to repeated cleaning, apply a solution of 10 parts water and one part muriatic acid, rinse within two minutes, and increase strength as necessary.

Finally, resolve permanent discoloration of cementious grout, such as found in front of urinals, by coloring.

Taf Baig is founder of the Reno, NV-based Magic Wand Company, a manufacturer and distributor of carpet cleaning tools, equipment, and supplies.