You can usually spot a loose tile if it's cracked, has loose chipping grout around it or makes noise and wobbles when stepped on. Knock on it and compare to surrounding tiles for a dead give away.
Remove any grout you can around the tiles you plan to remove.
Pry the tiles up with a tool from different sides. Try not to crack the tiles if you're reusing them. Otherwise just smash them with a hammer. If they don't pry up easily, they aren't that loose.
Pry the loose tiles up. Unless you're replacing the old tiles with new ones, keep track of which one goes where.
Carefully chip off any of the loose old mastic from the bottom of the tiles if you're reusing them. Try not to crack the tiles even more in the process. You don't have to get it all off.
Check the edges of the tiles for old mastic as well and scrape it off with the edge of the putty knife, no hammer needed.
Once your old tiles are scraped as much as you can safely get them without cracking them, put them to the side.
Chip up as much of the old mastic as you can manage off the floor. Use the putty knife and hammer as needed.
Once the floor is as smooth as you can get it, clean up any loose debris. A shop vac will do a lot better job than just sweeping.
Once the floor is clean from debris, you're ready to mix the mastic. Lightly dampen the floor first to prepare the surface for the mastic.
Mix the mastic to about a pancake batter consistency. You won't need too much if you're just doing a tile or two. Let the mastic sit for no more than 1-2 minutes, then re-stir, adding water as needed.
While the mastic is setting up, dry fit the tiles in their place to make sure it all seats nicely.
Flip the tiles back from their respective positions so you're not scrambling to figure out where everything goes once the mastic is on the floor.
Spread to mastic on the floor conservatively over the raised spots and liberally over the deeper spots.
The mastic will dry faster spread out like this so work fast. If you put too much mastic, the tiles will seat too high. Not enough and the tiles will still teeter-toddler and crack when stepped on.
Spread some of the excess mastic on the back of the tiles one at a time. Meaning do one and flip it, then the other, etc. I didn't have a trowel so i used the putty knife to make perpendicular groves.
Clean up the excess with a wet sponge. You may have to wash the sponge a few times. If you use a sink, leave the water running for a minute afterwards so the mastic cant collect & harden in the pipes.
Once the tiles are in place, firmly press down on them to press them into the mastic below. You can even step on them and use your body weight if you'd like, just be gentle, don't jump or anything.
So I clearly put too much mastic and didn't leave myself enough drying time to remove the excess. These cracked halves of the tile didn't line up perfectly.
If that wasn't bad enough, the tiles seated a bit higher than the surrounding tiles due to the excess mastic under them. But hey, if the client wanted perfection, they should have bought new tiles.
Not sure if its necessary but I would recommend letting the mastic dry and cure before laying the grout... even though I didn't.
Before you go to the store, you should chip up a clean piece of grout to match up the color. Pinch the small chip of grout in a piece of painters tape or you're sure to lose it in you pocket.
Match up the chip of grout from the job site with the new bag of grout at the store.
Get a bucket. Put a little water in it and mix up some grout. You don't need much if its just a few tiles.
Again, mix to about a pancake batter consistency and if you use your hand and wash it in the sink like I do, leave the water running for a minute afterwards so it doesn't collect and set in the pipes.
Use a tool to spread the grout out into the spaces between the freshly laid tiles.
Put it on liberally and press it firmly down into the cracks... That's what she said.... Sorry.
Clean up the excess with a putty knife.
Now use a damp sponge to clean up the excess.
The grout in the cracks will sit level with the tops of the tile, not sunken in like the rest of the floor. Don't worry, leave it alone. When it dries it will shrink to where you want it on its own.
Again, you may need to wash the sponge a few times.
When you're done the grout will be noticeably darker than the old grout around it. Don't freak out. When it dries it will significantly lighten in color. Obviously don't walk on it until the next day.
See how much the color lightened by the next night?
Try to plan ahead so you don't waste the excess mastic/grout. I stuffed my hardening excess into this gaping hole at knife point... That's what she said... Wait... You know what I mean.
Again, notice how much the color lightened by the next night.
Congratulations you're done! Any questions, just ask! -Med School Mike www.MissionMedSchool.com