It is somewhat painstaking.
There is a grout removal tool available at most big box hardware stores. It is basically a handsaw that uses hardened aggregate applied to the blade instead of teeth.
You have to shave each joint down to a level below the surface that a new grout can be applied to and adhere (about 1/8" for non-sanded grout and 1/4" for sanded grout).
If you are changing grout colors, you will want to use an acid (muriatic acid) to wash down the joint edges to remove any small amounts of the old grout at the surface edge that remain, prior to new grout installation.
Because you are not installing the new grout to the full tile depth, it is advisable to use a latex additive to prevent cracking.
If you have never installed tile and grout before, it is pretty easy to learn how to do grout. The first thing you need to do is to look at the width of your grout lines. If it is going to be less than 1/8 of an inch, you want to use non-sanded grout. If the width is more than 1/8 of an inch then you want to use sanded grout. Make sure that you put all of your grout tiles in place first.
Use spacers to make sure that there's an equal distance between all of the tiles. Then, you want to mix your grout paste and use a float to make sure you fill in all of the grout lines. the grout mixture should look like wet sand if you're using sanded grout, or it should look like thick cake batter if you are using non-sanded grout. Grout tends to hold better if it has just the right amount of water. It has too much water or too little it doesn't bond properly. After you are done filling in the grout lines, take a large damp sponge and wiped the tiles clean. That is it, you are done!
Its one of those things that is easier to show than to describe. Tip: If your gap is 1/8" or larger, do yourself a favor and use the stronger sanded grout. And use thin set instead of mastik. If you're going to do the work and it is a LOT of work, you want it to last.
remove the offending grout with a tungsten grout remover and regrout
If the tile is ceramic or porcelain you can use vinegar and water and a good scrub brush. It isn't an easy process and takes some work.
You have to rake out at least the top 3mm of the existing grout first.
Then you can re-grout with an appropriate grout as normal.
Since glazing is done through a firing process, you cannot practically re glaze floor tile.
Grout.
I have a lot of mould around my bathroom tiles and don't seem to be able to get it out from the grout in between. What grout cleaner will work best for this?
Grout should usually be white or contrast with the tiles, but it truly depends on your preferences.
if your grout line is less than 1/4" you use smooth grout, above that you use sanded grout.
First you lay out all the tiles with spacers adhering them to the floor, then you grout between by scraping across surface of tiles. Then just wipe clean. The grout is like a concrete mix & will harden.
No it shouldn't, but you should still grout your tile.
Ceramic tiles have a grout "gap" but vinyl tiles shouldn't have a gap.
One of the most important components of any tiling project is grout, a soft adhesive material that is used to fill in the seal joint spaces in tiles. When applying grout in between the tiles, the right type of trowel is needed to create the patterns that will match the back and side surfaces of the tiles. After the grout dries up, it is important to immediately sand the tiles and apply sealants. The sanding process can be done with standard sanding paper. Additionally, a soft moist sponge should be used to wash any excess grout from the top surface of the tiles. The sealant will help prevent dirt from accumulating in between the tiles.
there is a special cleaner at lowes in the cleaner isle.
To re-grout you mosaic tables, simply use tile grout. Be sure to remove the excess grout from the mosaic tiles to preserve the tables beautiful look.
"Grout is the stuff you apply between tiles to seal them in place. Grout tiles once the adhesive has dried fully (24 to 36 hours later). The best grout is waterproof and mould-resistant; some come ready-mixed. Use a grout float - a rubber-faced tool with foam backing - for large areas. Spread the grout across the tiles at right angles to the joins. Use a damp sponge to remove excess. Once the grout is dry, polish the surface with a dry cotton rag." I was taught by a contractor to apply and clean the grout diagonally.
Not JUST a grout no. You can get a cement that will also work as a grout but a pure grout would not have the adhesion required to stick the tiles to the wall properly, you should not use it as a cement.