Big Leaves Make the Best Patterns
I made a rustic leaf-embossed sand cast concrete bird bath for my garden last summer. It only took me about an hour to mix and colorize the concrete, mold it onto the leaf pattern, shape the edges, and cover the concrete so it could cure slowly.
It was a hot day when I started my concrete project, so I made sure I worked out of the sun to prevent the heat from curing/drying the concrete too quickly. Slow drying results in the strongest concrete. Fast drying may give you a crumbled mess.
The leaf shape concrete castis I made blends into my garden decor beautifully. The birds and butterflies love the shallow water depth and the broad edges of the leaf shape.
It's light enough so I can lift and dump out water and debris when it needs refilling or cleaning even though it's made from a thin concrete slab.
By the way, if you'd rather use this sand cast concrete leaf as a bird feeder, or a splash block for your downspout or garden hose, it works nicely for those purposes as well.
Sand Casting Materials and Tools
- Small pile of sand, or a bag of play sand
- Bucket of clean water
- Measuring cup
- Plastic dish pan or wheel barrow to mix up concrete
- Garden trowel to mix and blend concrete with water
- 3 large plastic trash bags, or 3 pieces of thin plastic sheeting (painter's drop cloths will work fine)
each one about 3 feet square
- Vinyl concrete patch mix
- 1 large plant leaf with prominent ribs and veins (Sunflower, Elephant Ear, Caladium, etc)
- Concrete colorant, if desired (I used a bit of terra cotta colorant for my bird bath concrete mixture)
- Protective Gear: Dust mask, rubber gloves, safety glasses
- Duct tape or waterproof masking tape
Concrete mix, dry or wet, is caustic and can irritate skin, eyes and mucous membranes.
Before opening your dry container of concrete mix, read instructions and safety information.
Always wear eye protection, a dust mask, and rubber gloves when working with concrete powder or mixtures.
Commercial grade vinyl concrete patch mix is the main ingredient used for this project.
Be Safe: Wear gloves, safety goggles, and a dust mask before starting to work with concrete mix.
Select and Prepare the Pattern Leaf
You'll be using a living leaf to create a "stamper" or as the texturizing mold for the embossed design on the surface of your bird bath.
Select a broad leaf with strong vein patterns and few or no defects or holes. For my first casting, I used sturdy leaves from a giant sunflower growing in my garden. Another time I used leaves from elephant ear plants we had growing in our summer garden.
Best results come from a large, freshly cut leaf with defined stem and ribs. Any large leaf will do, or if you want to make a smaller concrete casting, you can try nasturtium or squash leaves, or the big, textured leaves of the rhubarb plant. I've used those to make cast dishes and seed feeders for the birds.
Trim the stem end away from the leaf and patch any holes with small bits of waterproof masking tape or duct tape.
Prepare The Sand Cast Mold
Pour a mound of play sand onto a plastic sheet, or dump it into a child's small plastic pool or large waterproof tub. I spread a sheet of drop cloth plastic in the back yard, right on the lawn. You'll need just enough sand so that the mound will be slightly larger than the leaf you will use for the stamp pattern template. The pile should be about 4 inches deep at the top/center.
Mound the sand slightly (about 3 inches high) in the center, slightly larger all around than the size of the leaf shape. Smooth out and curve the mound down so that the edges are about at ground level with a bit of sand around the outside of where the leaf will rest.
Cover the smooth sand with a plastic bag or sheet of thin plastic drop cloth. Place the leaf on top of the plastic, face down, centered on the sand mound.
Now that you have your pattern leaf selected and your casting sand prepped, you can mix your mud aka concrete.
Casting set up, ready to mix and lay on the concrete.
Mix the Concrete
Following directions on the package, add water to the concrete powder mix starting with the minimum amount. If you want to add colorant to the concrete mix, add a small amount and mix in thoroughly with the water.
Use a small trowel or planting shovel to blend the mix, water and colorant together.
Stir well until the concrete mixture is the consistency of stiff cookie dough. The mixture should not be watery; it should be workable like play clay or craft modeling dough.
I like to add my own colorant to get a terra cotta look, but you could leave your concrete natural and paint it or stain it at a later time.
Molding the Pattern on the Leaf
To form the birdbath shape, place handsful of prepared concrete mix on top of the leaf, beginning in the center. Gently pat down to about 1" thickness as if you were making mud pies or rolled cookies.
Continue to add more concrete mix, patting and smoothing and working toward the outer edges.
When you have completely covered the leaf, gently press and shape the concrete with your fingers along the outside perimeter of the leaft to create a smooth rolled edge.
Take care not to add any sand to the mix or the casting; keep the leaf snuggly against the concrete and plastic.
Mud play time! Applying the concrete to the back of the leaf.
Curing Sand Cast Concrete
After all the concrete is smoothed out, cover the top and sides with plastic to let it cure for at least 24 hours.
After you've finished molding and shaping the concrete on top of leaf, carefully drape with another plastic bag or sheet of thin plastic to seal out rain or dust while the concrete dries and sets.
Weight down the sides of the plastic sheet or bag to prevent wind from blowing the plastic cover off and to keep most of the moisture inside.
Your project must dry slowly to properly cure and not crack, so keeping it covered lets the moisture evaporate gradually and cure the concrete to a strong, rock hard state.
Curing can take up to 2 days; don't rush it.
Finish the outside edge of your cast leaf by molding a smooth, rolled concrete edge along the entire perimeter of the shape.
Cleaning Cast Concrete
Your sand cast concrete project must dry completely before you remove the plastic cover. Drying/curing can take up to two days; I start checking after 24 hours.
When the piece feels dry to touch, remove the plastic, turn it over and carefully peel off the remaining bits of leaf matter from your molded concrete using your fingers or a soft manicure stick.
You many need to use a sharp tool to scrape off the really tiny bits, or wait a day or two and scrub the casting with a wire brush to remove stubborn bits.
If your casting is a bit rough, smooth out the spots after it's completely dry using a coarse sandpaper or dremel tool.
After initial drying and curing time is finished, turn over your casting, support it on the sand pile, and carefully peel and scrape off the leaf bits.
Durability of Small Cast Concrete Projects
Cast concrete garden crafts are generally weather proof after they dry and cure completely. You can decorate cured concrete with acrylic paints or concrete stains to add more color interest, or simply coat the finished project with a concrete sealer to make it easier to clean and add a glossy finish.
I cured my leaf pattern bird bath for a few months outdoors in the sun and rain, then I painted on a clear acrylic sealer. The sealer gave my leaf a wet look, and added more depth to the color, which made the vein pattern stand out nicely.
After sealing, the bird bath was stain resistant and easier to keep clean, plus water could not be absorbed into the concrete.
The coating only lasted a single season.I scrub my cast leaf at the end of the summer, then after it's dry I apply a new coat or two of acrylic sealer and put it away out of the weather for the winter.
More Uses for Your Cast Leaf Project
My sister uses her molded leaf as a serving platter for summer barbeques (she lines it with a napkin) ... and my mother uses her smaller molded leaf as a mail basket, in the house.
A friend uses his as a rain-diverting splash block under his downspout. I have several in my garden placed as art objects; one is supported by a piece of old clay tile pipe, and another is resting on the mulch below a shrub.
©2008 - -Lee Hansen (editor of this site)
My finished cast concrete leaf, all cleaned off and left to dry completely.
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