Intro: Leaf Castings
Leaf castings are a wonderful way to add a natural and organic element to your yard or gardens. I will provide basic instructions here, but more detailed instructions can be found on my website. http://www.gardensandcrafts.com/leafcastings.html (Update: 11/21/17: I have closed down the gardens and crafts website. Visit our new website www.VintageLiaison.com).
Step 1: Basic Materials Needed
Basic Materials Needed:
- Flat work surface
- Concrete Mix
- Sand or Fine Gravel
- Plastic Drop Cloth or Trash Bags
- Rubber Gloves
- Stiff Bristled Brush
- Concrete Sealer
- Disposable Foam Brush
- Dust Mask
- Shallow container for mixing concrete
- Shallow Box to contain sand (Optional)
- Concrete Dye (Optional)
- Acrylic Paint (Optional)
Alternate mix: 3 Parts Sand, 1 Part Portland Cement, and an equal mixture of water and fortifier (bonding agent).
Add water until the mixture feels like thick brownie batter. Mix well. Let mixture stand 5-10 minutes before applying to the leaf.
Choose a work area where the casting can sit and cure undisturbed for a week. Garages or covered patio areas work well. This can be a messy job, so wear old clothes or an apron to protect your clothing and always were rubber gloves when working with concrete because the Portland cement in the concrete is caustic and can burn your skin. If you plan on doing this project outside, choose a shady location and a time when it won't rain for at least two days. If the outside location is covered and partially protected from the elements, that is good too and rain is not much of a factor.
Step 2: Choose Your Leaf
Choose your leaf. Look for nice veining with no rips or insect marks. Cut the stem off completely so it does not get stuck in your concrete. Using fresh leaves is preferable, but some leaves can be kept hydrated for a few hours when their stems are kept in a glass of water.
Good candidates for leaf castings are Elephant Ear, Hosta, Rhubarb, Castor Bean, Gunnera, Caladium, Colocasia, Fig, Squash, Gourd, Cucumber, Pumpkin, Coleus, and Perilla, to name a few. There is no right or wrong leaf to use, that I am aware of. The only advice I can offer is to look around in your yard for a large leaf that resembles a round, oval or triangular shape that has a lot of veining on the underside and some substance too it. You don't want a flimsy delicate leaf that won't hold up to the concrete mixture. These make good birdbaths because of their larger shape, but don't discount
smaller leaves with good veining. They can be taped together to form a larger leaf or used as decorations for other projects.
Step 3: Prepare Work Surface
Prepare your work surface by laying a piece of plastic on the table and pile up some sand to make a nice mound. You can also do this inside a box if it will be easier for you to contain the sand. Wet the mound slightly with water from a spray bottle or a fine mist from the hose. You only want the sand damp enough to stick together, kind of like when you were making sand castles as a kid. You can pre-moisten the sand if that will be easier for you. The shape of the mound will determine the inside slope of your bird bath, so keep that in mind when forming its shape. The size of the mound should be slightly larger than the leaf you are using. Lay a piece of plastic on top of the mound to keep the sand from mixing with your concrete mixture.
Step 4: Mixture
Mix the concrete and water a little at a time until you get a brownie batter-like consistency. You do not want the mixture to be too soupy as the slurry can get under the leaf and make for an unattractive leaf casting. If the mixture is too dry,you won't see the vein details of the leaf. You want the mixture to sit on the mound of sand and not slide off.
Step 5: Putting Concrete on the Leaf
Place your leaf on top of the plastic sheeting that is covering the mound of sand. Make sure the veiny side is turned up and that it is centered on the mound of sand. Again, make sure that you cut the stem off the leaf. Start pressing concrete to the center of the leaf making it about 1"-1.5" thick, tapering to about 1/2"-3/4" thick at the edges. Keep adding concrete to the leaf until you just reach the edge.
Step 6: Pack Concrete
Now that the leaf is completely covered you want to gently pat the concrete to pack it down and to make it smooth so that there are no air bubbles on the veiny side. Be careful that the concrete doesn't slide down your leaf. If it's not too wet, this shouldn't be a problem. You can always hold your hand against the edge to help keep it from sliding, if this is a problem.
Step 7: Optional Pedestal for a Birdbath
At this point, you can build up the middle even further to create a pedestal so that the birdbath will sit up off the ground a bit. It is not necessary, just depends on where and how you want to place it in your garden. The pedestal should be at least half the size of the leaf width and it can be any height. Mine are only about 2"-3" tall. Once you have the desired size, take a board and flatten the top. You can use a level or just eye ball it to see if it appears level. Where you place it in the garden may not be level, so don't go crazy trying to get this level unless you plan on putting it someplace where this will be important.
Step 8: Optional Hanger
If you don't want a pedestal on the bottom, you can add a hanger at this point in case you'd rather hang your leaf casting on a fence or garden shed. To do that, take a piece of heavy wire, form into a loop and bury the ends slightly in the mixture, leaving the loop exposed. Wire coat hangers work well for this also. You may also not want to have the leaf cupped quite as much as when you would be using it as a birdbath, so modify the mound of sand before beginning your casting.
Step 9: Curing
Place a plastic bag loosely on top of the leaf casting and do not move it for at least 48 hours. This is very important to avoid breakage. The air temperature should be on the cool side, but not below 40 degrees. If you are experiencing hot temperatures, make sure you prepared it in the shade and it can be misted a few times a day if you think its curing too fast, but the bag alone should keep it from curing too fast.
Once the casting has cured for 48 hours, you can remove the plastic sheeting and work your fingers under the leaf so that you can flip the birdbath over to its rightful position. Peal the leaf off the concrete. It should come off pretty easily, but if it doesn't let it sit a day or two longer. If it still won't come off, you can use a wire brush to get it off after it has sat for 7 days, just be careful you don't rub off the pattern you have made on your concrete or chip the edges. The edges can be smoothed out by using a metal file or rock. Once it has sat for more than 72 hours, sanding the edges will become more difficult, so I like to perfect the shape before it has completely cured.
Step 10: Optional Stains and Paints
After 72 hours you can apply paints or stains to your project, as is the example on the right.
Check the label instructions of your paint or stain to see if it requires the concrete to cure longer. I use
Patio Paints for most of my castings and usually wait a week to make sure it is fully hardened to help avoid breakage.
Step 11: Sealing
After 72 hours the birdbath can be sealed with a concrete sealer. These sealers are clear and shouldn't change the color of your birdbath. Two coats should do it, but follow the directions on the sealer that you are using. Let dry for at least 24 hours. If you are using an outdoor paint, sealing may not be necessary. Check the label on your paints for further instructions.
Step 12: Additional Tips
If your birdbath won't hold water, check to see if it cracked during the curing process. Cracks can occur if the concrete cures too fast on a hot sunny day or it was moved too soon. If there are no visible cracks, the concrete is probably still absorbing too much water because there are too many air pockets. There are several ways this can be fixed.
Option 1 - Fixing a leaky birdbath
Mix a little Portland cement and water to create a slurry and coat the back of the birdbath. You may need to do two coats.
Option 2 - Fixing a leaky birdbath
Mix a little Portland cement and a white PVA glue (such as Weldbond or Elmer's) and coat the back of the birdbath. Make sure
the glue dries clear.
Option 3 - Fixing a leaky birdbath
Use a concrete sealer designed for leaky basements on the back of your birdbath.
Option 4 - Fixing a leaky birdbath
If you plan on painting your birdbath, this will usually eliminate the problem as well. You'll want to protect your paint job with an outdoor sealer or use Patio Paints instead of regular acrylics or latex paints.
Your concrete birdbath will be able to remain outside all year round, however, if you have heavy snow falls or below freezing temperatures, you may want to turn your birdbath on it's side or upside down so it doesn't hold water.
I prefer to let my leaf castings sit for 30 days before use. This ensures that all the paints, sealers, and the Portland Cement have fully cured. Curing is essential for a long lasting project.
A PDF of this project is available on my website. http://www.gardensandcrafts.com/leafcastings.html