I have tried various attachments on a Dremel-type device, without much success. The litttle discs disappear in double quick time - but make little impression on the grouting. However, one slight slip, and they mark the surface of the tiles. A little conical metal thing with bits of diamond on was slightly better - but most of the diamond bits had gone after going round one tile.
So what *does* one use to chop out the old grouting?
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