I am attempting to replace or clean old, stained kitchen floor tile grout. How can I easily remove the old grout?

The pricy and easy way is the Fein Multimaster. Watch the video on this page: C. & E. FEIN GmbH - Der FEIN MULTIMASTER (http://www.fein.de/fein-multimaster/us/en/applications/replacing_tiles.html)

The rotozip is another popular way.

If the grout is in good shape, and only needs cleaning, a steam cleaner might work. It required a bit of muscle, but worked well for the bathroom that we used it in.

As for removing the grout, I have to second KISS's answer. The Fein Multimaster is absolutely the easiest and fastest way to go. And, it's also probably the least messy. It doesn't kick up the dust as much as a dremel tool or rotozip. Unfortunately, they're not cheap, but they'll save you a couple of hundred dollars of frustration, so you need to factor that into your costs. If your grout is exceptionally hard, you'll probably want to spring for the diamond blade.

There is stain that will change the color of your grout rather than removing and replacing it, just an option if you want to avoid some extra work. Here is a link for one of them:

Grout Stain (http://www.super-tek.com/groutstain.htm)

If the grout is in good shape, and only needs cleaning, a steam cleaner might work. It required a bit of muscle, but worked well for the bathroom that we used it in.

Isn't a steam cleaner an upright machine like a vacuum cleaner? So I assume you mean that the scrubbing is what used muscle. I'm in the same situation as Cheryel. I would like to try and clean the grout if possible.

Lol I did floor laying for a while and had the same problem actually on a new floor that we installed. Home owners had tracked mud on it before we had a chance to seal it. What we used was muratic acid. Now do not use too much of it just a couple of table spoons in a 3-5 gallon bucket. That and a little elbow grease you should be good to go

Stains should be removed as earliest as possible. Stains affected area should be rinsed thoroughly. Use the detergents that are specially made for the stain marks.

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tile and grout restoration (http://www.tile-grout-equipment.com)