Removing old, hardened grout from tile joints can be a major pain. There are a lot of ways to go about it, but almost all of them involve either damaging the tile, generating tons of grout dust, or both. (We can tell you first hand that grout dust is not good for your health.)
We’re not saying that this is an inexpensive solution by any means, but if you’re re-grouting some priceless tile or are removing grout on a daily basis — we’ve been there and feel your pain — Fein has a tool that does the job without making a mess of the tile or your lungs.
Their FSN 400E dustless grout remover works by vibrating a sandpaper-like “blade” (using fine diamonds for grit) at up to 22,000 times per minute to pulverize the grout into pieces small enough to wipe away but not so small that they’ll fill the air. It features variable speed settings, and you can attach the blade in 12 different configurations to optimize its shape for your particular task.
The FSN 400E retails around — get ready for this — $675 in various kits. It’s easier to find in Europe than here in the states, but if you look around a bit you can indeed find it.