I am tiling a hearth with 4X4 slate tiles. I installed the tiles over
a month ago and sealed them twice.

Today I grouted the hearth and it was a total mess. I used a float to
work the grout all over the hearth and this seemed fine. Then I got up
a reasonable amount of grout with the float. The grout directions said
to wait 45 minutes at that point so I waited... then I started
removing the grout on the tiles using spones and rags and it was a
complete mess. None of the grout was dry (maybe this is correct---this
is my first attempt at tiling) and I had to work like crazy to get the
grout off the tiles.

At this point all of the tiles are clean, which is nice, but there is
hardly any grout left in the tile joints. This is because of the
scrubbing and rubbing that I had to do to get the grout off off the
tile faces.

I am sure that I did something wrong because the grout lines are pretty
ugly, not smooth, etc.

I am suspicious that I removed the grout too early and that I should
have waited until the grout in the joints was hard. Is this right?
Any other ideas here? The sealer evidently worked because when I look
at the tiles now I see grout only in the joints.

Assumign that I can figure out what I did wrong, I want to re-grout the
entire hearth so that the grout lines look good. Can I just put
another layer of grout on top of the existing grout? THe hearth will
not be a heavy traffic area. I am going to place a woodstove on it
when I am done.

Thanks, mh