An Introduction to Grouting Mosaics

By Claudia Wiegand

1. WHICH GROUT?

The main criteria for choosing the right grout are:

Is your project for indoors or outdoor use?
If your mosaic is for indoor use, will it be in contact with water?
Which type of colours have you used to make your mosaic?

INDOOR vs. OUTDOOR

If your mosaic is designed to stay outside (house number plate, garden table, garden mural, planter etc), it needs to resist any weather condition, including frost. You will need to use a waterproof grout suitable for outdoor applications. This is available from specialist tile suppliers and usually comes in natural colors such as off- white, sand, various shades of grey and sometimes terracotta.

If your mosaic is a decorative project for inside the house, you can either use a standard grout (usually available in a number of colors such as white, cream, sandstone, grey and charcoal) or use a ready-mixed grout you can find at your local DIY store. Ready-mixed means a little more expensive than the grout you mix yourself, but if you only do small or occasional projects, it’s very handy.

CONTACT WITH WATER

If you mosaic a splashback or mural in a bathroom for example, choose a waterproof grout.

For areas subject to larger amounts of water (shower areas, swimming pools), you will need to use resin epoxy grout, which is very resistant even if you have a power shower.

THE IMPACT OF GROUT COLOR

The grout color can enhance or ruin your mosaic! It can draw you design together or break it.

Generally, if your design is abstract, it won’t be much of a problem, but if it is figurative, you need to make sure you use the right colored grout.

Light grout will generally make your design look paler and very dark grout will make it somber, even if you use the exact same tiles. It’s worth making a couple, or even three similar samples using the same mix of colored tiles and grout the 3 pieces with white, medium grey and charcoal grout to actually see how different they look.

Generally, if the majority of your tiles have a light color, use a light grout. If the tiles are mainly vibrant hues (strong reds, blues and greens for example) or dark, go for a dark grout. Using medium grey grout is quite safe and will accommodate most of the tile colors. Use pure white grout if you want to achieve a clean, crisp look for a bathroom piece for example.

Grout can also be colorized using artist’s acrylic paints, liquid colorizers or pigments and this can further bring the design together. For example, if your mosaic is mainly blue, colorize grey or white grout with blue paint or pigment. Make sure you mix the grout thoroughly and prepare enough to cover your entire piece. Achieving the same shade of blue twice would be practically impossible.

2. HOW TO PREPARE GROUT

If you decide to mix your grout yourself, make sure you wear goggles and dust mask so you don’t inhale any powder. Grout, like cement based adhesive, is very abrasive, so do wear latex gloves too.

It is difficult to estimate the amount of grout you’ll need to cover your whole mosaic, so try and test. Prepare a small amount first to see how far it goes. Using a large spoon, transfer powder into an old bowl and add water, a little at a time. Mix with a stick or another spoon. You’ll see how quickly the powder absorbs water. The grout should have the consistency of a thick paste, not liquid. If it is too liquid, add more powder. If it gets too hard, add just a little water (sometimes a few drops are enough).

If you add powder pigment to the grout, mix the pigment with the grout powder before adding water. If you add acrylic artist’s paint from a tube, mix the color after you’ve mixed grout powder and water. Give it a good mix to make sure the color is uniform.

3. HOW TO SPREAD THE GROUT

Use a squeegee and apply the grout in different directions to ensure the grout fills all the gaps. Try and scrape off as much excess grout as possible and wait for 5 minutes before wiping the mosaic with a dry cloth. If the grout has dried to much, use a wet tiler’s sponge, making sure you have squeezed as much water out as you can. The sponge should be nearly dry, otherwise it will remove grout from the gaps between the tiles. Leave to dry overnight, then wipe off the thin dust film with a dry cloth to make your mosaic shine.

If you use ready-mixed grout, you will probably need to re- grout a second time as the grout tends to sink more than the one you mix yourself.

For larger areas like walls and floors, use a grout float, it will make your task quicker and easier.

Don’t hesitate to use your fingers for intricate areas, but remember to wear latex gloves.

Always scoop and scrape off unused grout from your bowl and put it in a plastic bag or newspaper before you dispose of it. Wipe your bowl clean as much as you can with an old rag or newspaper, then rinse it. Never dispose of grout in the sink! It will block your pipes.

4. A FEW WORDS ABOUT CRACKED GROUT

Grout can sometimes crack if the base hasn't been primed - wood will absorb too much of the grout moist and the grout will dry too quickly.

If grout dries too fast, it will tend to crack. It's a good idea to cover the grouted and cleaned mosaic with a plastic sheet or a damp cloth to slow down the drying process. Don’t leave your mosaic to dry near heat.

You can always add some flexible additive to the grout (from tilers' shop), which is especially used when mosaicing over wooden floors. It makes the grout a little more elastic and less susceptible to crack.

If some areas of the grout do crack, simply re-grout.

Where Do You Go From Here?

You could try out Claudia's mosaic course. She explains a simple mosaic project step by step and and gives you loads of useful info on mosaic techniques. For more details head over to http://www.mosaicsforfunandprofit.com

Please remember to consider and take appropriate safety precautions before and during any art or craft project.

Some craft projects on this site may be unsuitable for children. In any case, adult-supervision is required all children's craft activities and projects.

This article is reprinted here with the author's express permission.

All views, opinions and ideas expressed in this article are those of the article's author and not necessarily those of Answers 2000 Limited.

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