How to Lay Out a Mosaic Design

Print the design you want to work to, then lay a sheet of clear contact paper over it sticky side up and tape all four corners down.

Everything gets built on top of this. The sticky surface holds each piece exactly where you put it, which means a knocked table no longer destroys an afternoon of careful placing.

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Set each cut piece of glass down onto the contact paper, following the printed design showing through underneath.

This is the part that usually has to be done in one nervous sitting. Here it does not: the adhesive stays tacky for days, so you can stop halfway through, walk away, and come back to a layout that has not moved a millimetre.

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Work in the fine details now rather than after grouting. Ball chain makes flower centres and stems, and micro beads fill the awkward slivers between petals that no cut piece of glass will fit.

These details are most of what separates a mosaic that looks finished from one that looks like coloured shapes on a board.

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Score the surface all over in a crisscross pattern with a utility knife so the adhesive has something mechanical to grip, sand it back to remove rough spots and any factory coating, wipe the dust off, then paint the whole area white.

White matters if you are using transparent or translucent glass. A dark base underneath drains the colour straight out of it, which undoes all the work you did choosing shades.

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Cut a second piece of contact paper, this time trimmed closer to the size of the substrate so it will not stick to the taped-down bottom sheet.

Lay it sticky side down onto your finished layout and press firmly over every piece, including the tiniest ones. Anything you miss will stay behind in the next step.

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Turn the whole sandwich over, then slowly peel away the original bottom sheet.

Go gently and watch for pieces wanting to lift with it - if one does, press it back onto the top sheet and carry on. What you are left with is the entire layout locked to a single sheet, upside down and ready to move in one go.

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Dry-fit the sheet on the substrate first to confirm it sits where you want it. If it does, spread adhesive evenly across the whole surface and lower the mosaic on.

Miss a patch of adhesive and you will not find out today - you will find out in a month, when a tile lifts.

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Press gently over every piece so each one makes full contact, then stack something heavy on top and leave it overnight.

The weight is not only about adhesion. A wooden base will warp as the moisture in the glue moves through it, and weight is what stops that. Once it is dry, peel the top contact paper off slowly.

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Mask the edges, put on gloves and a mask, and mix grout with water to a peanut butter consistency. Let it slake for 5 to 10 minutes, then press it into every gap and scrape the excess back.

Buff the haze off after about 30 minutes and again the next day. Then seal the grout - it protects against moisture and stains and keeps a dark grout from fading.

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