On Thu, 13 Sep 2012 07:12:12 -0400, Norminn wrote:

clipped

http://www.prosourcecenter.com/catalog/10090GroutSaw.jpg


Are you sure about this .... "add clean grout on top of the old" ? It
just doesn't sound right to me. And I would think it would just be
easier to remove all the old grout but this isn't a fun job either.

I don't know of an easy option. Removing some of the old grout....I
think removing 1/8" depth is minimum to give new grout a secure bed...is
the only way to renew it. Unless you try sandpaper and then resealing.
I removed and replaced grout in a tile shower stall that had 1x4 tiles
and fine grout lines. Hard work with a Dremel grout tool, but doable
(and I'm an old lady). Most difficult were getting down to do the
lowest portions and then putting in new grout; it takes some muscle to
mush in the new grout.

I also replaced the grout in a shower surround using a Dremel tool to cut the
old tile out. I found a source on the Internet for the bits; would have gone
broke with Dremel bits, at $10 each. I think I went through 20 bits. If I
had to do it again, I'd use the grout saw for a multi-tool. The rotary motion
of the Dremel tended to pull the bit into the tile.