To make mosaic coasters: choose a design, prepare a sealed base, cut and test-fit the tiles, glue them down, let the adhesive dry completely, grout, and seal. A set of four takes an afternoon plus drying time. Work within a 4″×4″ square and leave room for grout between the pieces.

Coasters are the project most people should start with. They are small enough to finish in one sitting, flat enough to forgive uneven cutting, and useful at the end. Mosaic tile and glass mosaic tile are also genuinely suited to the job — they are tough, they resist water, and they look good doing it, which is more than can be said for a plain slab of cork.

What you need

Choosing a base

Blank coaster bases are easy to find online in both round and square shapes. Wood and cork-backed MDF are the two easiest to work with.

Seal the wood first, and make sure it is dry. This is the step people skip and regret. Mosaic tile copes with water spills and condensation perfectly well; bare wood does not, and a cold glass will put condensation on a coaster every single time it is used. Sealing it is the difference between a set that lasts years and one that warps in a month.

Painting the base in a complementary colour is a good alternative finish, and it also solves the problem of what shows through the grout lines at the edges.

How to make mosaic coasters, step by step

1. Choose the design. Sketch it at full size — the same 4″×4″ square as the finished coaster — so you can see how many pieces you need, what size they should be, and where the grout lines fall.
2. Outline it on the base. Simple designs do not need this. For anything more elaborate, trace the pattern out on paper first and transfer it onto the base before any tile goes down.
3. Cut the tiles. Nip the pieces into the shapes the design needs.
4. Do a dry run. Lay the whole coaster out without adhesive. This is the cheapest moment to discover that a piece does not fit.
5. Glue the pieces down with a water-resistant adhesive, working from the centre outward or along the main line of the design.
6. Let the glue dry completely. Grouting over adhesive that has not set will lift pieces.
7. Grout — optional, but it is what makes the surface smooth, stable and usable. Work it into every gap in one session, let it set about 20 minutes, then wipe the tiles clean with a damp sponge.
8. Seal with a marble sealer. Grout is porous, and a coaster exists to catch red wine and coffee.

Design ideas

Three approaches, in rough order of difficulty.

Relaxed designs

Large tile pieces, generous grout lines, no stress about precision. Black grout with big pieces gives a bright, graphic result — a heart in a field of blue, for instance — and the large tiles are easy for small hands to pick up and place, which makes this the best style to do with children.

This is also the style that suits leftovers. Roughly rectangular offcuts from a previous project, set in horizontal lines, make a perfectly good set of coasters with no cutting at all.

Geometry

Adding structure takes the result somewhere closer to modern art: repeating shapes, a tight palette, something between a quilting block and a Frank Lloyd Wright window. A Mid-Century Modern palette works particularly well on coasters, and gold glass mosaic tile in an organised pattern gives a set a noticeably more formal air.

These demand even spacing more than precise cutting. Leaving a little more room between pieces makes the pattern easier to execute, not harder.

Designs that need a little planning

Still achievable without much trimming, but worth roughing out on paper first. Radiating bands of colour with a small budding branch across them. Round, celestial-inspired designs using a mix of glass and standard tile scraps. Or a set of four coasters that stand alone individually but join into one larger image when pushed together — a good trick, and a natural way to use up an assortment of offcuts.

Glass tile deserves particular consideration for coasters. On a table in sunlight or lit by candles it behaves quite differently from stone, and a coaster is one of the few mosaic pieces that sits out on display during exactly those moments.

Beyond tile: coasters from unusual materials

Mosaic does not have to mean tile. These four work on coasters, trivets, box lids and small panels, they cost almost nothing, and they are good projects to do with children.

Dried beans and lentils

You need: assorted dried beans and lentils (the more varied in size and colour the better), a surface such as canvas, tile, plywood or an old patio table, thin paper, a pencil, glue and varnish.

1. Sort the beans and lentils into piles by type, so you can pick from each without hunting.
2. Choose a design — a flower, something abstract, a portrait, a landscape.
3. Draw it roughly on thin paper first, to see how it will look.
4. Transfer the drawing onto the surface. Either copy it freehand with the paper beside you, or slip carbonless copy paper between the drawing and the surface and retrace the edges.
5. Glue a small area at a time and lay the lentils onto it. Wait about 15 seconds, then press down gently so they bed in.
6. Repeat section by section until the design is covered.
7. Spray the whole surface with varnish for a glossy finish.

Seashells

You need: seashell pieces, a surface, a sponge brush, paint, mosaic adhesive, grout and a spatula.

Keep the broken shells next time you are on a beach — broken pieces are better for this than whole ones.

1. Choose the surface: a nightstand, a jewellery box, a papier-mâché box, a coaster.
2. Paint it first with a sponge brush. Not mandatory, but a colour matching the hue of the shells makes a better finish. If the piece is going outdoors, use a paint rated for it.
3. Decide the pattern — sketch and transfer as with the lentils, or scatter the shells at random.
4. Apply mosaic adhesive to a small area and set the shells into it. Press with a small flat piece of cardboard rather than your fingers — whole shells crack easily, and broken ones are sharp.
5. Mix grout in a disposable container, something you will not use for food again.
6. Spread the grout over the whole surface with a spatula rather than your fingers — it gives a more even layer and keeps you cleaner. Work it into every crevice.
7. Once the grout has dried, wipe the excess away with a damp sponge, rinsing and repeating until the shells reappear. Go carefully, or you will pull grout back out of the gaps.
8. Clean up the edges and leave it to dry overnight.

Beads

You need: beads, bead glue, carbon paper, paper, a pencil, colouring materials, painter's tape and tweezers.

Beads are small and slippery, so sort them by colour before you start — small containers work, and a cupcake tray is ideal, one colour per slot. It saves far more time than it costs.

Sketch the design, transfer it with carbon paper, then place the beads with tweezers. This is the most detailed of the four and the one that rewards patience.

Dyed pasta

Colour dried pasta with liquid watercolours in a sealed bag, shake it until evenly coated, and let it dry. Arrange the pieces on plywood, a box lid or similar — abstractly or in a pattern — glue, and finish with varnish for shine.

With children: supervise throughout. The hazard with these materials is swallowing glue or small pieces rather than sharp edges.

Mosaic art kits · Mosaic designs · How to start mosaic art · Natural stone tiles

Frequently asked questions

How do you make mosaic coasters?

Choose a design and sketch it at full size, prepare a sealed base, cut and test-fit the tiles, glue them down, let the adhesive dry completely, grout in one session, wipe clean after about 20 minutes, and finish with a marble sealer.

What size should a mosaic coaster be?

4″×4″ is the standard. Sketch the design at that size and leave room for the grout lines between the pieces.

What base should I use for mosaic coasters?

Blank wood or cork-backed MDF, round or square. Seal the wood first and make sure it is dry — a cold glass leaves condensation on the coaster every time it is used. Painting the base in a complementary colour is a good alternative.

Do mosaic coasters need to be grouted?

Strictly it is optional, but grout is what makes the surface smooth and stable, and it holds the pieces against knocks. Coloured grout also changes the look of the design considerably.

Do mosaic coasters need to be sealed?

Yes. Grout is porous, so a marble sealer after grouting keeps coffee and red wine out of the grout lines.

What tiles work best for coasters?

Mosaic tile and glass mosaic tile. Both are tough and water-resistant. Glass is more striking in direct light or candlelight; stone reads warmer. Offcuts from a previous project work perfectly.

Can you make mosaics without tiles?

Yes — dried beans and lentils, seashells, beads and dyed pasta all work on coasters and small panels, finished with varnish, or with grout in the case of seashells.

Are mosaic coasters a good beginner project?

They are the best one. Small, flat, quick, useful, and forgiving of uneven cutting — and a set of four gives you the repetition that actually builds the skill.

Image credits

• Lentil mosaic reference: Make a Mosaic with Lentils
• Seashell mosaic reference: Shell Grotto, Margate
• Bead mosaic reference via Flickr
• Additional coaster design photography sourced via Pinterest