I have very little experience with this sort of thing, so after reading and watching you-tube videos I attempted a test patch - a 3 tile wide, 1.5 tile deep section (these are 12" floor tiles). And now, I have questions…
- Removing the old grout
I purchased a hand grout saw for the test patch. My grout lines are 1/4", so the saw is significantly narrower. I tried to cover all areas but kept finding myself with tiny parallel ruts. I finally resorted to running the saw at a slight angle. This helped, and did not seem to be damaging the tile, but I never saw any recommendations to do this so I'm wondering if it was a bad idea?
I also wasn't sure how much of the old grout to remove. I basically just got the dirty layer off.
For the whole big job I plan to use a Dremel; there are two different types of blades for this, one that's basically a powered version of the hand saw and another that uses a bit that can be set to a particular depth. Is one more appropriate than the other for this job? And can I expect to have less trouble taking the old grout off evenly?
- The grout
I have a feeling that my grout choice was too sophisticated for me. :) I used TEC Power Grout RTU, which is a premixed sanded grout that doesn't need sealing. It sounded perfect. However, in reality it was very thick, nothing like the wet mud texture I saw in all those videos. I got it spread but it required quite a bit of elbow grease and was very difficult to get smooth.
The original grout, at least according to the builder, was TEC sanded powder grout, which I would have to order from Lowes. I had thought that using the premixed stuff would protect me against having mixed it incorrectly, but now I'm not so sure.
EDIT - I returned the grout I had bought (I have to give Lowe's credit for allowing this, since I had used some) and ordered a bag of the same brand and color of powdered grout that the builder says they used. This should help with the amount of effort it took to get it spread.
- The application
As I said, the grout fought me every step of the way. It rolled up into balls, it stuck more firmly to the rubber float than to the floor, and was just generally aggravating. However, I did finally get it to go where it belonged. The exception was the edges, where the grout line met the wall or the cabinet. It was impossible to move diagonally over the line in those places, which is essential to working with this stuff. Is there a trick to getting the edges right?
- The cleanup
This was the smoothest part of the process, but I did notice that by the time I got the tiles clean there were obvious places in the grout lines where it was not applied thickly enough. I don't know if this was an application failure that I didn't notice because of the covering of grout everywhere (even after scraping with the float at 90 degrees) or if I was actually wiping away some of the product. Either way, I didn't know if it was ok to apply more with the surfaces wet, so I left it alone.
This was only a test, and I fully expected to have to remove this grout and replace it, so I have already succeeded no matter how it looks. But I think I am going to have to get a different grout - the color was much whiter on the floor than in the tub or brochure, even though it's supposed to dry the same color, so we'll see. Right now it is too white for the tiles.
EDIT - having changed the grout, I have one further question. The grout I will be using is TEC AccuColor Sanded Grout. Their website describes this as a "polymer-enhanced portland cement grout" but doesn't say anything one way or the other about whether it needs to be sealed as an additional step. I think that the polymer-enhancement means it does not, but can anyone confirm that?
So - there's my tale, I'm hoping those with more experience than I can make some suggestions on how to make it go better the next time!