How Do You Join Clay Without A Slip?

Clay slip is a liquid mixture of clay and water used to join pieces of clay together. It acts as an adhesive to bond the clay surfaces. However, there are a number of techniques to join clay without using a traditional clay slip. These “no-slip” methods provide their own advantages. Joining clay without slip often results in a tighter bond and removes the risk of the slip drying out and becoming a weak point. It also gives the artist greater control and precision when assembling complex forms. Overall, knowing how to join clay without slip increases flexibility and options for ceramic artists.

This article will overview the main techniques to securely join clay pieces without using ceramic slip. We’ll cover methods like rubbing, burnishing, scoring, adding water or oil, and more. With some practice, ceramic artists can achieve strong bonds between clay bodies without the need for messy and unpredictable slip.

Table of Contents

Prepare the Clay Surfaces

Properly preparing the clay surfaces is crucial for a strong clay joint. Start by wedging or kneading the clay thoroughly to remove any air bubbles and evenly distribute moisture. Wedging involves cutting the clay in half, slamming it back together, and repeating. Kneading is pressing, folding, and squeezing the clay. Both techniques help improve the clay’s plasticity.

Next, use a rib or surform tool to smooth out the clay surfaces that will be joined. Remove any dust, debris, or loose particles that could weaken the joint. The smoother the surfaces, the tighter the clay connection will be. You can also use a moist sponge to gently wipe the clay surfaces clean.

Work on a clean surface and avoid touching the join areas with your fingers, which can leave oils that inhibit adhesion. The clay is now ready to be joined.

Moistening the Clay

Moistening the clay is essential when joining clay with the techniques that use pressure, like pressing, rubbing, or burnishing. Without enough moisture, the clay will crack and crumble instead of melding together.

Pressing

Pressing is one of the simplest ways to join clay without a slip. With dry hands, line up the edges of the pieces you want to join, making sure there is contact between the surfaces you want to connect. Apply even pressure to the clay, either by pushing the pieces together with your hands or resting a flat board or other object, such as a tile, on the top piece of clay to press it down evenly.

You will only need to press the clay for 10-30 seconds to make a solid bond. Avoid pressing too much or holding for too long, or you may deform the shape of your pieces. Just enough time for the clay particles to come together is all that is needed.

With evenly applied pressure and a moderate hold time, you can successfully join clay pieces without the use of slip or glue.

Rubbing

One of the easiest ways to join moist clay pieces is simply to rub them together. This generates friction heat, which softens the clay surfaces and effectively welds them as the clay particles become integrated across the joint. Rub the clay surfaces together in a back-and-forth motion, applying pressure against each other as you go. the longer you can continue the rubbing motion, the stronger the weld will be.

Be sure not to twist the pieces as you rub. This can cause the clay to tear rather than properly bonding together. You may need to periodically moisten the area as the friction dries out the clay.

Burnishing

Once the clay pieces have been pressed or rubbed together, use a smooth, rounded burnishing tool to further strengthen the bond. Hard tools made of bone, stone, or metal work best. Gently rub the tool along the seam in a circular motion, applying moderate pressure. The friction and heat created by burnishing helps meld the clay pieces together into one cohesive whole. As you burnish, run your fingers over the clay to check for gaps or uneven areas along the seam. Continue burnishing until the seam feels smooth and is barely detectable visually or by touch.

Burnishing not only fuses the clay; it also compresses, smooths, and strengthens the seam, creating a joint nearly as strong as the clay itself. Over time and exposure, unburnished joints may show cracks or start to separate. Burnishing provides important reinforcement and waterproofing against these issues.

Scoring and Slip Trailing

This method combines two popular techniques to strengthen joins between pieces of clay or clay parts without needing to use extra clay paste or liquid clay slips. Scoring means deliberately creating long grooves in one or both clay surfaces that are to be joined together. Shallow bubbling grooves work best, about 1/8 to 1/4 inch deep.

You can score clay with a knife, fork, or other handy tool with narrow tines. Be careful not to cut too deeply into the clay body which may compromise its strength. Scoring the clay surfaces adds extra texture that slip can adhere to.

The slip is made from the same clay as the project, preferably moistened into a thin liquid state. Use a small spoon, brush, or eyedropper to carefully trail small amounts of the slippery clay liquid into the scored grooves and channels. Capillary action helps draw the clay into the crevices.

Press the scored clay pieces together and hold for a few seconds to enable to two surfaces to fuse tightly thanks to the added slip and interlocking scores. The scored lines filled with more clay act as reinforcing ridges for a super strong join.

Additives

Adding materials such as grog, sand, brick, or coal to clay before joining is another technique that helps in fusing without using a slip. These materials create texture, allowing for better adhesion between the clay surfaces to be joined. During firing, the additives will evaporate, leaving tiny holes within the clay body that the clay will flow into.

Common additives for joining clay without using slip include:

Grog – Pre-fired and ground-up clay that helps prevent cracking and control shrinkage.
Sand – Natural texture to help with adhesion. Different sand types will influence color and texture.
Crushed brick or tiles – Adds earthy red colors while aiding joining.
Coal – Burns away during firing, leaving interesting dark speckles and pockets.

The texture from these additives gives the clay surfaces more grip and allows joining without using slip. The additives burn away during firing, leaving the clay to fuse together firmly.

Clay Type Considerations

When joining clay pieces without slip, the type of clay is an important consideration. Here are some recommendations for the most common clay types:

Earthenware

Earthenware clay is typically soft with an earthy color. It tends to have a porous structure and lower firing temperature. Moistening the clay surfaces before joining should give enough moisture for the pieces to stick. Burnishing is recommended to meld the clay surfaces together.

Stoneware

Stoneware clay is denser and less porous than earthenware. It needs more moisture and force to successfully join pieces without using slip. Scoring the surfaces and rubbing them together can help to meld the clay.

Porcelain

Porcelain clay is very fine-grained and non-porous. Its hard surface requires roughing up with strong scoring and cross-hatching before attempting to join. Generous moistening, pressure, and rubbing should help surfaces meld together. Burnishing will further smooth and join the clay surfaces.

Conclusion

There are several effective techniques for joining clay without relying on ceramic slips, ranging from simply moistening and pressing the clay together to more advanced methods like burnishing, slip trailing, and additives. Each approach has its own advantages – choosing the right one depends on the clay type, the desired strength of the joint, and any decorative concerns.

In general, joining clay without slips requires patience and practice as it may not achieve the same strong bonds initially. However, avoiding slips opens up creative possibilities and more expressive surface results. Slipless joins may also better survive any clay expansion or shrinkage during drying and firing. The simple act of rubbing clay surfaces together creates wonderful fissures and textures that can enhance organic or hand-built look.

Learning to successfully combine clay with or without slips is a valuable skill for any ceramic artist. As with most techniques, experimenting with the different joining methods on test pieces is key before incorporating into finished artworks. Mastering these basics empowers more artistic freedom in the studio.