Some Fundamentals to Remember
- A gap of 3mm is generally used to allow the grout to flow completely into the space between the tesserae
- Aesthetically, bigger tesserae can support wider lines and smaller tesserae thinner lines
- You should be aiming to have consistent grout spacing over the whole mosaic (i.e. consistently thin or consistently thick grout lines). This can be virtually impossible to achieve when using irregularly shaped tesserae (e.g. broken crockery), but try to achieve consistency when possible.
- There may be instances where you intentionally vary the thickness of the grout lines, for instance wider grout lines may be used to emphasis a shape.
- Using thick grout lines over the entire mosaic can cause the mosaic to appear fractured and disjointed.
- Thin grout lines are usually better than think grout lines.
Colouring Your Grout
The colour of your grout is very important - it can make or break your piece. Grouting unites the mosaic and highlights the layout of the tiles.
What coloured grout should I use on my mosaic?
The colour of your grout should contrast the colours of the tiles so that the design is highlighted. If the colour of your grout blends in with your tiles the individual tiles will be lost and the mosaic will look more like a picture than a mosaic.
As a general rule:
- White grout can appear very harsh, as it will draw the eye to the gaps rather than the coloured tiles. In saying that it compliments lighter tones so it is very good for showing off pale mosaics, but when used with strong bright colours it will produce a Mediterranean feel.
- Dark grout unifies darker coloured tesserae and segregates lighter ones.
- Grey grout enhances most coloured tesserae and has the most unifying effect of all the coloured grouts.
How can I get coloured grout?
You can buy coloured grout or use cement oxides and acrylic paints to colour it yourself.
Opinion varying on the use of acrylic paint as a colourant. Many books suggest using it as a colourant but others point out the following negatives: it requires lots of paint, can produce a pale coloured grout and may affect the integrity of the grout itself.
How do I use different coloured grouts in the same project?
Using different coloured grouts in the same project is fiddly and tricky. Start with the lighter coloured grout first and clean up any edges prior to applying the darker grout. I use a cleaning tool that I picked up when doing ceramics, it has a sharp pointed blade at one end and a curved blade at the other. Once you've applied the lighter grout carefully cover it with masking tape and apply the darker grout. Be careful that the darker grout doesn't seep through to the lighter grout. If the darker grout does seep through you should be able to remove it with a sharp instrument or file. Warning - Patience is required to achieve a good result.
Be aware that the colour of the grout changes as it dries. So, if your uncertain of how it will look when it is dried I'd recommend mixing up a test batch.
A Simple Process for Choosing Your Grout colour
Make up a number of test panels with the tile colours you've used in your project. This can just be as simple as gluing the tiles onto a spare piece of board.
Mix up different grout colours
Grout the pieces and allow them to dry completely before making a decision
Don't rush this process, make as many test panels as you need to find the right grout colour.