Allocate Enough Time! Make sure to allow enough time to complete the grouting process. How it looks when you go to bed that night is how it will look forever without a considerable amount of extra work. Try not to grout more than you can comfortably complete in 2 hrs.
Protect areas of your art you don't want to be damaged by grouting. Such as mirrors, frames etc. Simply mask these areas with low tack painter's tape. After grouting pull back the tape and smooth out any rough edges.
Once you have all of your tools assembled it's time to mix your grout. You want a consistency similar to cookie dough. There is no exact proportion, it depends on the manufacturer and the humidity. Thicker is better and easier to clean up and is less likely to crack or have air bubbles.
WEAR A MASK and safety glasses. Until the grout is mixed the power is dangerous to your lungs…and think about it, your eyes too!
How much grout? Estimate 1.5 - 2 cups of dry grout per sq. foot but it really depends on how far apart and how deep your grout joints are. It is better to have leftovers than to have to stop in the middle of a project to mix more grout. This is an area where it a matter of experience. The more you do it, the better you will get at judging how much to mix. You can also check the packaging for a bit of a guide. Most all grout manufacturers include a table to give you a good idea of coverage.
For large projects, like walls, where you may use more than 1 bag of grout, dry mix 2 bags together as color and dye lots may differ between bags.
If you are custom coloring be sure to reserve some dry mix if possible and to mix enough to finish. You don't want to run out, it is always difficult to color match later. For tips on exactly what to do watch this YouTube video:
Coloring Thinset mortar and Grout Video
For small projects mix your grout in some type of small plastic disposable container. Empty sour cream, dip, cottage cheese and ice cream buckets work well. When you are finished you can simply toss it in the garbage.
When mixing it is easy to get the grout too wet at the last minute of adding liquid. When you feel like you're getting close add water in small increments. A good trick is to use a spray bottle, less likely you will over-water. If it gets too wet add a little more powder.
Once mixed allow the grout to slake (rest) for 10 minutes before using this allows the chemical reaction to begin. Then stir again and begin the application. Slaking is a necessary process and makes the grout stronger. Do not add more water or grout once the grout has slaked as this will weaken the grout.
Your goal in applying the grout is to solidly fill all of the spaces between your tesserae. Force the grout into these spaces by applying pressure with the float, the side of your hand, a mud tool, or as seen in some of our videos a small, dry Cello sponge. Pull diagonally across the mosaic until all of the joints are filled. Removing most of the excess off as you go.
Here's the hard part. Once you have most of the excess grout removed. Wait! Allow the grout has set up, usually 20-30 minutes. How long this process will take depends on the humidity, temperature, etc. Then gently wipe with a very dry damp sponge, or if a small art piece just paper towel or newsprint. The less water you use in the clean up the better. With glass products, especially stained glass, often the damp sponge is hardly needed. Next polish clean with paper towels or a soft rag. I like old sweatshirts and t-shirts. Rougher fabrics like towels do not work well and tend to pull too much grout from the joints.
When selecting sponges ordinary kitchen sponges with large holes are not a good choice for cleaning grout off your project. The larger holes will produce a rougher surface and pull too much grout out of the joints. Always choose a sponge with small cells or one specifically intended for grouting. These are readily available at home improvement stores and tile shops. If you need something smaller than the large grout sponges sold in stores simply cut your sponge into quarters. It will be much more manageable.
Sometimes you will get a "grout haze". This is common. If you can't buff it off with a dry cloth wait a day and mix 50/50 white vinegar and water and with a soft rag rub on tiles, then immediately follow up with a buff using a dry rag (T-shirt). This is very effective. If this does not remove haze you can try commercial “grout haze remover” or use Sulfamic Acid. This is a mild acid and will usually take care of any haze. Wear rubber gloves and have a clean bowl of water nearby. Rinse thoroughly with clean water when finished to stop the chemical process.
