Pebble and Shell Mosaic

It’s late January 2021, and I am extremely grateful for my creativity during this pandemic. My illustration commissions, personal projects and creative contributions to our local community, have all together helped me to stay fairly cheerful much of the time and focused on ideas and pleasant practical issues. Most recently, to add interest and colour to our garden (another great source of comfort), I’ve made a small mosaic using stones and shells. Here’s a photo of the mosaic, which is in four recesses of a stone plinth we use for a bird bath. It’s a wet day so you can more easily see the variations in colour.

I’ve made mosaics before using my own hand-made tiles and found objects such as keys and buttons, but only for indoors. Our garden is a very different environment. The UK is by no means one of the wettest places on the planet but it certainly seems like it to me. For what feels like most of the year our garden is damp with rain and also, from spring to late autumn, heavily shaded by a mature oak tree. Algae and mosses flourish and only woodland flowers really thrive. Any mosaic made for out there needed to be very durable. Also, with the woodland environment in mind, I wanted it to have a natural look. I love vibrant mosaic work using glass and tiles, but I decided to make use of the more muted pebbles and shells that I already had stored in jars and pots around the house and garden. Here is a photo of some of the storage jars in my studio.

Pebbles

Pebbles are lovely things. Fragments of rock (between 4 – 64mm diameter, according to Wikipedia) that have been smoothed slowly over time by the action of water. Pebbles are found on beaches, in rivers, lakes, ponds, etc., but also inland where there was once sea. Pebbly rock has been found on Mars, providing evidence that there was once water there. Some of the pebbles I used for my mosaic came from beaches I’ve visited over the years, but it is better to get them from a garden centre or DIY store rather than from beaches, where collectively they form a natural sea defence by breaking the formation of big waves. I found most of my pebbles while digging in the garden over the last twenty-five years and I have used them for landscaping or stashed them in pots with creative projects in mind. I concentrated the beach pebbles and largest shells on the part of the plinth facing our house (shown above), as these were the most interesting and would be the most visible.

The earliest pebble mosaics date from the 9th and 8th centuries BC. Pebbles were the most popular material for mosaic decoration for thousands of years. Then, around the 3rd century BC, the use of pebbles evolved to cut stone cubes, or tesserae. Pebbles were increasingly added to with stone tesserae chosen for greater colour intensity. There are, however, many examples of ancient pebble mosaics still in existence because the materials are so durable. Pebble mosaics continue to be made, especially for flooring, and the techniques and materials have basically remained the same.

Pebbles range in colour from white to black and include grey, brown, green, yellow and red. They usually look darker when wet and darken to different degrees so I found it useful – especially as the pebbles are going to be out in the rain a lot – to wet them before use and sort them into colour groups, as well as groups of different sizes and shapes. The quality of pebbles would be an important consideration for a floor mosaic that is going to get a lot of wear but for this project I didn’t worry about about holes, cracks or veins in my pebbles.

Shells

My first encounter with shell craft was in the 1970s as a child when I broke a shell-covered lamp of my mums while messing about with my brother. I had not really noticed this lamp before I broke it but I certainly noticed it then! People have delighted in seashells and collected them for decoration since the Stone Age. They are seen in the oldest examples of jewellery, and they have also been used in mosaics. Seashells are a mixture of organic and inorganic material structured rather like a brick-and-mortar wall to protect marine animals from the rough action of waves as well as from predators. They are tough and therefore work well in mosaics. Even so I chose the hardest of my shells for my mosaic – limpets and large, thick cockles, in colours that suited my design, and went further, reinforcing my shells by filling them with exterior filler (layer upon layer) which I allowed to fully dry before adding the shells to my mosaic. Clearly I was traumatised by breaking that lamp…

I have a number of jars full of shells from UK beaches around the house but although shells are beautiful objects, as I get older I am less inclined to collect more. Empty shells on beaches are an important part of coastal ecosystems, used again by coastal wildlife for all sorts of reasons. They can provide nesting material for birds, and a home or anchor for various plants and organisms. Empty spiral shells especially are essential to hermit crabs looking for a bigger home as they grow. Anyway, shells are always at their most magical when found wet on a beach amid the sounds and smells of the seaside.

Design

I’d like to show you photographs of my mosaic in its various stages but I decided to start this blog a few days after making it. For future blogs I will aim to take pictures as I’m going along. Those would have shown you that for the design of my mosaic, I cut out four pieces of paper, each the size of the recess I’d be working in and tried out arrangements. I soon realised that I needed more pebbles and went off on a hunt around the garden. Sorting the pebbles by size and colour helped with the design, but I realised I was limited by a small design area and pebbles very similar in shape. There was an appealing range of colours though, so I decided to simply use colour order from cool greys at the bottom to warm ochres and reds at the top, suggestive of a rainbow or sunrise. Because the large pebbles were so rounded the gaps between them needed to be filled with smaller pebbles.

My husband (who lifts weights every morning while I lift coffee) brought the plinth into my studio for me. It was cold, like a giant ice-cube. As it slowly warmed I experimented with techniques for transferring the design onto the plinth. What worked best in the end involved placing the stones in the recess first and then gluing them in one by one, pressing each back into the arrangement already there, rather than trying to bring the design over from the paper which made me quickly lose track of it.

Glue/grout

So far in my limited mosaic adventures I have not yet used grout. Instead, I’ve packed the mosaic pieces together, attached them to a board using adhesive glue and pressed gritty sand into the surface of any excess glue bulging out from around the pieces. An example of this is my fish mosaic on the home page. I’m not sure what has held me back from using grout but I think I definitely need to jump in and do that with my next mosaic. 

There is plenty of advice about making outdoor mosaics if you search for it and it all seems to suggest that it is best to avoid adhesives altogether and use a concrete product. From what I have seen, these usually have to be mixed from powder. However, for this project I used a waterproof outdoor construction adhesive for both my glue and grout. I wanted to do this mosaic slowly indoors – adding a few stones here and there when I had the time – and I knew this would be very difficult to do with cement. I’ll be interested to see how the glue stands up to the test of time and weather. Having glued the stones, I also used the adhesive as a grout (I didn’t need much for this as the stones were quite tightly packed), squirting it gently into the cracks and gaps using a plastic syringe. Very satisfying!

Here is a photo of the other two sides of the plinth. These are mainly stones from the garden so there is less variety in colour but I did my best with what I had.

Sand

To disguise the stark whiteness of the glue for a more natural look I used gritty sand. The glue had a strong surface tension that enabled me to press the sand delicately with a brush into the very top surface of the glue/grout after all the stones had been glued in place. I let the glue dry thoroughly indoors for a few days before putting the plinth back in place in the garden. It looks just as good after a fortnight of rain and snow so that’s a good start.

Books I referred to when making the mosaic and writing this blog:

Brody, Mark, with Sheila Ashdown, Mosaic Garden Projects: 25 Colourful Step-by-Step Projects. Timber Press, 2015

Howarth, Maggy, The Art of Pebble Mosaic: Creative designs and techniques for paths and patios. Search Press, 1994

King, Sonia, Mosaic Techniques & Traditions: Projects & Designs from Around the World. Sterling Publishing, 2003

Maguire, Mary. New Crafts: Shells: 25 practical projects using shapes and textures of natural shells. Lorenz Books, 2013

Scales, Helen. Spirals in Time: The Secret Life and Curious Afterlife of Seashells. Bloomsbury Sigma, 2015

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