I would like to share with you how I go about creating my ceramic murals. Though the photos in this post are of my Trumpetor Swans mural which is 28″ x 89″ x 1″, the principles used in making this piece apply to a mural of almost any size.
Any mural project starts with an idea. In this case, I was drawn to the magnificent Trumpeter Swans that can be found in Oregon where I live. I started plowing through photographs on the web of these birds, and decided on depicting five swans in flight with a silhouette of the Central Oregon Cascade mountains at the bottom edge of the piece. This view is from the east, which is what we see here in Bend. I pasted together the different chosen photos of swans and made a Photoshop composite with a rough outline of the mountains and the sun.
The next task was to decide on a finished size for the piece, and then build the clay slab for the mural, taking into account the fact that wet clay shrinks during drying and firing. I use a sturdy, highly grogged clay body called “Timberline Sculptural” from Georgies in Portland. The listed shrinkage rate for this clay is 11% but I have found from experimentation in my kiln that it is more like 8-9% when fired at Cone 6. If you know what the shrinkage rate is and the size of the finished piece, you can calculate the dimensions of the wet clay slab you need using this formula:
Wet size = Finished size divided by (1 – shrinkage percentage)
In this case, my wet length = 89″/(1-.08) = 89/.92 = 96.7″ and my wet height = 28″/(1-.08) = 28″/.92 = 30.4″. If you have a specific dimension the mural has to fit in, it is always better to make the mural slightly too small that too big. You can easily make the grout lines wider but it is horrible if you have to cut your beautiful handmade art work to get it to fit if your fired piece is too large. I rounded the wet dimensions to 30″ x 96″. Remember to calculate your wet thickness too.
Making the slab
Now that I had my dimensions, it was time to use the slab roller and roll out the clay. I use Shimpo’s heavy duty slab roller and it works really well. It is super beefy and you can get precise thicknesses for your slab ranging from about 1/4″ to 2″. Plus it is cheaper than the competitors’ models. I clamped two work tables together and taped a sheet of plastic down so the clay would not dry out from below.
Stitch it together
I had a friend who took Peter King’s architectural ceramics workshop many years ago and she showed me how to stitch slabs together. His book on the subject is Architectural Ceramics for the Studio Potter but it seems to be out of print. Basically the edges of the two slab pieces are cut at 45 degrees and scored well. Then you slather on lots of slip on both edges and press them together. Then you deeply score the joint with a needle tool, cover with lots of slip, and press a roll of clay into the joint. Finally you smooth the top surface with a strong metal or wooden flat rib tool.
Keep it covered
It can take quite a few hours to create the mural slab. I cover the finished area with plastic and towels to keep the plastic held close to the surface. You don’t want the clay drying until you are ready to cut the mural into smaller pieces for firing.
At last the slab is done and ready for relief work and surface texture!
Add the relief carvings
I had created pencil drawings at scale of the five swan shapes. I transferred the designs to a rolled out slab by laying the paper on top and traced the design by lightly pressing with a ball stylus tool. Then I cut out each shape with a needle tool, gently laid it on the main slab, and found its proper position. I lightly traced its outline, and scored the main slab inside the traced line and also the underside of the swan piece. I added slip to both scored areas and pressed the piece firmly onto the slab. You have to be very careful not to get any air bubbles under the piece so using a rib tool I pressed from the center of the piece out to the edges. Air bubbles will expand during firing and blow the piece into a thousand bits.
All the pieces have been attached. Whatever carving and textures I wanted to add are complete. The plastic has been removed to let the piece begin drying.
Cut it up
Once the piece has firmed up a little, I use a needle tool to cut the slab into pieces suitable for firing and glazing. I will often cut away a little extra clay to leave some room for grout in the finished piece. I always try to make cuts that follow the curves of the design rather than simply create a rigid grid of rectangles or squares. Here you can see squares in the areas where there is no design but the rest of the carving follows the shapes of the birds, sun, and mountains.
In this photo the clay has already dried quite a bit. Nowadays, I put the individual pieces on wire shelves as soon as I cut them. You have to careful when handling the wet pieces but I find I get less warping if they can dry evenly from above and below. Don’t forget to number each piece on the back and create a map so you can put everything back together again later.
Bisque, glaze and fire!
After the pieces have dried to leather hard, I will clean up all the edges. When everything is completely dried, it is bisque fired to cone 04. Then glaze is applied and the piece is fired to cone 6. Once out of the kiln I reassemble the mural and enjoy the finished project. Woo hoo! When a final home is found all the pieces will be mortared in place and then grouted with a dark grout. The grout really ties everything together and gives a beautiful finished look to the mural. This piece is available in the shop here if you are interested. I am also available for custom commissions if you have an idea you want manifested in clay.
Thanks for reading!