dh, I'm confused.

When you say you 'grout flush with tile', do you means that it is completely level with the tile surface? i.e not below the surface.
If so how do you acheive that?
I finish off with a wash boy, then 'tool' the grout line with a paint roller (without the handle) along the grout line, and it gives a 'U' shaped finish, and looks good.
I'd be intrested to know how you do it. Always willing to learn new techniques.
Cheers mate
