I love flowers (who doesn’t?) and am always trying to find more ways to bring nature indoors. I’ve also long enjoyed small, precious things. The micro vase satisfies both desires. A very small vase can sit on your windowsill, hold a few flower stems, and add color and life to your home. I love bringing clippings from whatever is currently blooming in my garden inside to fill my windows. These wee vases are little lively gems that bring joy to life!

Creating the Model

I slip cast the micro vases because that allows me to make them at a faster rate. I then add handbuilt knob handles to give each vase a unique personality. I make my own molds using a rough-and-ready technique that doesn’t require a lot of equipment. In addition to regular clay tools, the only extra items you will need to make your own mold are a bag of #1 Pottery Plaster, mold elastics (wide elastic bands made to hold mold sections together, available online), and liquid slip-casting clay. Note: You will want to designate a set of tools to use only with plaster and make your mold in a separate area from where you work with clay. 

Begin by creating your model. Throw or handbuild a small vase between 4–6 inches in height. It should be either solid or fairly thick. There should be no undercuts (areas that would get stuck in the mold once it is poured and sets up). Add a ¾-inch-high sprue to the top. Let the model dry to firm leather-hard consistency, then use a highlighter to draw a line just to one side of the middle that defines where you will block off half of the model (1). The dividing line between each side of the mold needs to be exactly half of the form in order for it to release from the mold properly. 

1 Use a highlighter to draw a line where you will block off half of the model.2 Create a flat surface along the highlighted line using clay strips.

On a board (any type of sturdy, waterproof board will do), use clay to create a support under the model. Roll out a ½-inch-thick slab and cut it into 1–1½-inch-wide strips. Carefully, without marking the surface of the model, use the strips to create a flat surface along the highlighted line (2). Press them in firmly. Use ¾-inch-thick slabs to create a cottle around the outside edge of the strips that will contain the liquid plaster. The height of the walls should be 2½ inches higher than the top of the model. Use coils to fill in any seams (3). You’ll have a 1–1½-inch area around the whole model except for the top, which will have the cottle along it (4). Finally, reinforce along the bottom of the outside to the board for support using additional coils.

3 Fill in seams with coils to prevent any liquid plaster leaks.4 This is what the prepped mold should look like before casting the plaster.

Creating the Mold

When mixing plaster, the optimal ratio of water to plaster is 73 parts water to 100 parts plaster. This equates to 1 quart of water to 2 lbs. 14 oz. of plaster. I recommend using the instructions for amounts and proportions found on the Ceramic Arts Network website (ceramicartsnetwork.org/daily/article/Plaster-Mixing-101-How-to-Mix-Plaster-for-Ceramic-Molds). Pour the plaster in to fill the cottle up to the same height above the model as you have width on the sides. Immediately after pouring, gently shake or tap the table to coax any air bubbles in the liquid plaster to release. 

5 Create keys in the plaster of the first half of the mold using a trimming tool.6 Round out the exterior edges with a rasp, then wipe the surfaces clean.

Once the first half of the mold is set (about 40 minutes, after the plaster has heated up and cooled off), remove all the clay parts except for the model. Use a trimming tool to create half-circle keys in the plaster (5). Secure a clay-slab cottle around this part of the plaster mold. Make sure the surfaces are clean, and then apply a very fine layer of petroleum jelly or Murphy’s Oil Soap onto the visible plaster to keep the two parts separate. Pour the second half of the mold to an equal height as the first half, and when set, remove the cottles. Use a rasp to round off the exterior edges of the mold (6). Remove the model, gently wash the mold to remove any plaster debris and clay bits, then set it aside unassembled to fully dry.  

Slip Casting Your Mold

Once the mold has dried, it’s ready to slip cast. Use mold elastics to hold the two parts tightly together. Mix the slip well and pour into the plaster mold (7). Regularly top off with more slip as the level recedes due to absorption. Once the piece is thick enough (you can check by cutting a small section from the narrow part of the sprue), pour out the remaining liquid casting slip. Let the piece set, still in the mold, until it is strong enough to hold its shape when the mold is opened. 

7 Pour the well-mixed slip into the mold, then periodically top off as needed.8 Cut off the excess clay along the seams with an X-Acto knife.

Cleaning and Finishing

Cut off the excess clay along the seams with an X-Acto knife (8). Sponge the form clean. To form your knob handles, roll tiny, tapered coils from a clay body with the same recipe as your casting slip (use the clay cut from the seams and the sprue if it is plastic enough), and shape them into spirals. Add a dab of liquid slip to each of the sides of the form in turn. Press the spirals into the liquid casting slip to connect them (9). Once the connections have dried, sponge around the knobs to clean them up. Voilà! One micro vase is now yours to decorate as you like. 

9 Press spiral handles into dabs of slip to connect them to the form.

Shana Salaff is a ceramic artist, writer, and educator living in Fort Collins, Colorado. To learn more, visit www.shanasalaff.com or follow her on Instagram @shanasalaffartist.

Topics: Making Ceramic Molds, Handbuilding Techniques

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