Alice Medley loves to create works of art from the pebbles she collects. And she was generous enough to invite us into her garage workshop to show us how to make these beautiful pebble mosaic stepping-stones. She uses a “dry-set” technique that makes it easy to change or adjust the pattern as you go without having to dig the stones out of wet mortar.
In addition to showing you how to make these stepping-stones, we’ve included plans for an ingenious reusable wooden mold that Alice purchased from a North Woods carpenter. The initial investment for this project—about $50—gets you the plywood, a bag of mortar, pigment and muriatic acid. It’s enough material to make about seven or eight stepping-stones. After that, each one will cost you less than a dollar.
Meet the Expert: Alice Medley
Alice started out using more traditional mosaic materials like tile and glass for her outdoor art projects. Then she discovered she could marry her love of stones with her love of mosaics. Alice learned this dry-mortar technique from Laura Stone, a stone mosaic artist from Minnesota. Alice has also created 4-ft.-diameter, built-in-place pad for her backyard fire kettle using the same technique and is waiting to see how it holds up through harsh Minnesota winters.
Alice collects her stones on the north shore of Lake Superior. You’ll find similar stones in most parts of the country. Look for them in river and creek beds or along lakeshores. Wherever you find them, make sure you have permission and that it’s legal to collect them. Another possible source is your local landscape supplier or wherever landscaping stone is sold.
Alice likes to sort them by color. She’s got buckets and cans full of red, gray, white, brown and speckled stones. Keeping them sorted makes it a lot easier for her to find the right one as she creates a pattern.
A small sheet of 3/4-in. plywood and some 1-1/4-in. screws are all you’ll need to build the mold. Cut out the pieces according to the Cutting List. Figure A shows how the parts go together. When you’re done, brush linseed or vegetable oil on the mold to protect it from moisture.
Photos 2 – 4 show the assembly steps. Alice likes to add a little brown pigment to the dry Type S mortar mix to give the stepping- stones a mellower look. You’ll find cement pigments and Type S mortar at home centers and masonry suppliers. Or you can cheat like Alice does and just mix in a little colored ceramic tile grout. Make sure to wear rubber gloves to protect your skin from the mortar, which can cause skin burns.
You don’t have to plan your pattern ahead of time. Alice says she has a design in mind and just starts arranging the stones. It’s easier to start along the edges or in a corner and work toward the center, though. You’ll have less fitting to do as you fill in the last few stones. Keep the stones close together and oriented with the long axis up and down. While it’s tempting, Alice cautions against laying a stone flat. She says it doesn’t look as good as you think it will and is more likely to pop out later. When you’re done tamping the stones into the dry mortar, inspect the space between the stones to see if there are spots that require more mortar. They should be buried at least halfway. Fill sparse areas with more mortar. Dust any dry mortar off the stones with a small brush.
The trickiest part of the process is wetting the mortar (photo 5). We can’t tell you exactly how much water to add, but it’s better to sprinkle on several small doses than to get impatient and risk adding too much. Alice says the key is to alternate between wetting the top and tapping on the mold with the rubber mallet until it seems like not all of the water is being absorbed and bubbles quit appearing (photo 6). Expect to spend about 45 minutes sprinkling and tapping. When the mortar is thoroughly dampened, set the completed stepping-stone in a shady spot and cover it with a damp cloth and plastic. Wait at least 48 hours before removing the mold.
After you remove the mold from the stepping-stone (photo 7), brush the stone off to remove any loose mortar and rinse it with clear water. If, after drying, the embedded stones have a film of mortar on them, clean it off with muriatic acid diluted according to the instructions on the container. Remember, always add acid to water, not the other way around, and wear rubber gloves and safety glasses.
To enhance the color of the stones, coat them with stone sealer. Alice recommends Sparks Stone Glamor sealer. You can find it online at sparkssw.com for $18 per quart. Other brands will also work. You’ll find stone sealers at home centers; masonry, landscape and tile suppliers; and online.