Proper way to use a grout saw?

[Ratdog]

Hi folks,

I'm a novice at re-grouting, and need to repair some cracks in my bathroom tile grout. I have purchased a grout saw, and upon first use it seems that I am also scuffing the tile itself in the corners where the wall meets the floor.

Basically, could you please inform me if a grout saw should be used flat against the tile or held into the grout at an angle, perhaps halfway between the wall and floor?

I just want to make sure I don't damage the tile surface by using a poor technique.

Thanks

[HayZee518]

grout saws are hand type or a blade that installs in a sawzall or in a zip tool. grout is portland cement and a very fine sand with a binder. regular steel blades will get dull very quick. grout saws use carbide which is very hard but brittle. use the saw lightly at first until a groove is formed then increase pressure. when you get near the bottom of the grout line go easy. it is very easy to puncture through the cement board or sheetrock. the edges of most glazed tile has a slight bevel to it, then it is raw ceramic. grout sticks to the rough edges.