This is an original technique I use for making portrait busts out of grout. Grout is like cement, except it is stickier and doesn't shrink. When cement dries it shrinks and tends to crack, which the grout does not do.
To make the finished bust lighter I use a mold to make crumpled aluminum foil cores. The cores can be bent some to give position variations.
The grout I use, "Keraset", comes in a light gray color. The grout can be given a variety of colors, depending on the addition of powdered pigments. The pigments are available in hardware stores for coloring cement. Right now, I am mostly making clay-colored grout using a combination of red and yellow pigments.
Step 1: The Mold
The 2-piece mold was made out of cement many years ago, and I don't have photos of its construction.
The core shape was originally sculpted in clay. Using mold-making techniques, I made a 2-piece mold of the shape.
The left and right halves of the core are molded out of crumpled aluminum foil. The halves are then taped together. The neck can be bent to provide position variations.
Step 2: Packing the Mold Halves With Aluminum Foil
I like to line the mold with one or two layers of aluminum foil, like a skin, before packing it with more randomly crumpled aluminum foil. That gives a fairly smooth surface for the first layer of grout to stick to, and gives the core more structural integrity than it would have without the skin.
Since aluminum foil doesn't stretch, it will tear if you force it into the recesses of the mold. Tearing of the skin layer is avoided by first crumpling the aluminum foil to create a quilted pattern of wrinkles. That shrinks the area covered by the foil, but allows the foil to stretch out again without tearing as it is pushed into the mold.
I use a ball on a stick as a tool to help push the foil into the mold. Leave some excess skin hanging over the edge of the mold. It will be folded back over the crumpled foil in the middle to help hold it in place.
I usually fold up a pleated strip of foil and put it through the neck area to give the neck more strength when it is bent later.
Fill the skin with crumpled foil, fold over the skirt around the edge onto it and remove the core half from the mold.
Step 3: Join the Halves
The left and right aluminum halves of the core are taped together. Three bands of tape around the eyes, neck, and chest do the job.
Step 4: Coloring the Grout
I mix the grout and pigment powders in a 5-gallon plastic bucket with a lid. I shake it about 50 times in a circular motion. Let it sit for a while so any cloud of dust inside the bucket has a chance to settle. Try not to breathe any grout dust.
Step 5: Mixing the Grout
I made a boat-shaped mixing bowl out of silicone rubber. It can be flexed and scraped to remove even hardened grout since nothing much sticks well to silicone rubber. The boat shape is for ease in pouring when it is used with plaster of Paris to make molds.
I usually add the water first and then the dried powder. Stir with an old spoon, or other tool, or by hand, but you have to wear plastic or rubber gloves. I use "disposable" gloves, reusing them until they tear. The thin material almost lets you feel like you are working bare handed.
The grout can be mixed with varying amounts of water to give it thicker or thinner consistency. It all has its uses.
Step 6: The First Layer of Grout
Wet grout is fairly heavy and sags, so you can't do too much at first without a rigid core. These prepared cores let me sit down with the model and start in on the facial features right away, saving the model's time in the initial stages. Since the core is already hard, it supports the weight of any added grout during the sculpting process.
Rub the first layer on with your gloved hand, or mini-trowel, such as a palette knife. It's quick and easy. I do a layer on the bottom of the core first and then set it down on a flat, non-stick plastic sheet to finish coating it. That way the bottom is plastered and out of the way. It has a flat and smooth surface when hard.
The plastic I work on is moisture barrier material used underneath cement slab floors in house construction.
Step 7: Sculpt the Bust
Using hands, or sculpture tools, sculpt the material as you would clay. These busts take me about 7 or 8 hours to make, which includes about 4 hours of the model's time.
Unlike clay, which can be kept moist and pliable by preventing evaporation, the grout is in a continual process of hardening up once it receives water. It's always easier to add more fresh grout to the bust later than it is to carve away hardened grout, so try not to over-shoot your mark if you can avoid it.
Please excuse the unnatural colors of some of the photos. I don't know what causes my camera to go wacky on the colors at times. It's time for a new camera, I guess.
Step 8: Other Busts I Have Made
These are some other busts I have made over the years.