What Is The Best Clay For Outdoor Sculpture?

Outdoor sculpture refers to any three-dimensional artwork designed to withstand the elements when placed outside. Unlike indoor sculpture, outdoor works must stand up to varying weather conditions like sun, rain, snow, and wind. The popularity of outdoor sculpture has grown over the last few decades as more cities, parks, universities, and other public spaces look to install large-scale works to enrich the community.

When creating sculpture for outdoor display, the type of clay used is crucial. Clays can vary greatly in their chemical composition, affecting factors like durability, plasticity, firing temperature, shrinkage, and more. Sculptors must consider weather resistance, structural integrity, and aesthetic qualities when selecting the best clay for an outdoor piece.

The three main types of sculpting clay are earthenware, stoneware, and porcelain. Earthenware contains lower levels of fluxes resulting in more porous works that require protective sealants for outdoor use. Stoneware has higher flux content, creating less porous, denser pieces that withstand weather better. Porcelain is highly refined and fired at the highest temperatures, producing very dense non-porous sculptures suitable for outdoor settings.

Weather Durability

Outdoor sculptures are exposed to the elements year-round. Understanding the local climate and weather patterns is crucial when selecting the right clay. Temperature extremes, moisture levels, and sunlight exposure can all impact how well a sculpture holds up over time.

Areas with cold winters and hot summers require clays that can withstand freezing temperatures as well as high heat. Repeated cycles of expansion and contraction from temperature changes can lead to cracking or crumbling if the clay body lacks elasticity. Likewise, regions with high humidity or frequent rain events need clays with low permeability to prevent water from seeping in and eroding delicate details.

The intensity of sunlight is another key factor. UV rays can fade colors over time, especially darker pigments. Prolonged sun exposure may also cause some clays to dry out too quickly before curing is complete. Choosing a clay with good stabilization and low shrinkage will help outdoor sculptures maintain their shape and structural integrity through seasons of sun, rain, and fluctuating temperatures.

Common Clays for Sculpture

There are several types of clay that are commonly used for sculpting, each with their own advantages and disadvantages.

Polymer Clay

Polymer clay is an extremely versatile sculpting medium made from PVC resin and plasticizers. It comes in a wide range of colors and can be blended and mixed to create custom hues. Polymer clay is lightweight, making large sculptures easier to work on. It can be sculpted with excellent detail and does not dry out while working. Finished pieces do not need firing in a kiln. The clay cures and hardens when baked at relatively low temperatures. While very workable, polymer clay is not as strong as ceramic clays when cured. Pieces are susceptible to damage if dropped or hit with force. Extended outdoor use can also cause discoloration and degradation over time.

Oil-Based Clay

Clays like plasticine and Roma plastilina are made from fatty oils mixed with fillers and waxes. This makes the clay quite soft and easy to manipulate into detailed sculpts. The clay remains workable indefinitely if kept wrapped. However, pieces made from oil-based clays cannot be hardened and will slowly deform over time. Finished sculptures must be constantly supported or encased in an armature. Oil-based clays are best for temporary works, animated films, and maquettes. They are not suitable for permanent outdoor display.

Water-Based Clay

Clays that use water as a plasticizer include pottery clay, ceramic clay, and self-hardening clays. These clays can be sculpted when soft, then left to air dry or fired in a kiln. The firing process permanently hardens the clay by bonding the particles. Water-based clays can be very strong and durable when properly fired. Pieces can withstand outdoor display for many years. However, these clays require more specialized tools and equipment. Shaping the clay is more difficult when wet and drying can cause cracking. Overall, water-based clays produce the most permanent and weather-resistant sculptures.

Factors When Choosing Clay

When selecting the right clay for an outdoor sculpture project, there are several key factors to consider:

Durability – For a sculpture that will live outside, durability is perhaps the most important factor. The clay needs to be able to withstand all weather conditions – rain, snow, wind, freezing temperatures, and intense sun – without cracking, crumbling, or deteriorating. Choose a clay rated for exterior use.

Cost – Clays formulated for outdoor use tend to be more expensive than standard clays. Consider your budget constraints when selecting materials. It may be worth investing more upfront for a higher quality clay that will last longer term.

Moldability – The clay should be malleable enough to sculpt intricate details and hold shapes without slumping or sagging as you work. Assess the plasticity and workability of the clay.

Firing Requirements – Make sure you have the proper kiln for firing the type of clay you choose. Some outdoor clays require higher firing temperatures than regular clays. Under-fired pieces will not reach full strength and durability.

By evaluating durability, cost, moldability, and firing requirements, you can zero in on the best clay option for your specific outdoor sculpture.

Best Clays for Outdoor Use

When it comes to selecting the ideal clay for outdoor sculpture, there are a few types that stand out above the rest. Two of the best clays for withstanding the elements are stoneware and terra cotta.

Stoneware clays are extremely durable and resistant to weathering and moisture. They can withstand multiple freeze-thaw cycles, as well as rain, snow, and temperature fluctuations. High-fire stoneware clays are often used for large outdoor installations. The dense clay body and sturdy physical structure prevents cracking, crazing, and deterioration.

Terra cotta is another premium choice due to its longevity and resilience. Natural terra cotta clay contains silica and alumina that provides strength and minimizes warping. It can survive years outdoors through sun, rain, and seasonal shifts. The clay’s natural earthy tones also develop a beautiful patina over time.

Both stoneware and terra cotta are excellent clays for crafting sculptures, planters, fountains and other pieces destined for the outdoors. Their superior durability comes from the high firing temperatures that vitrify and strengthen the clay. When properly sealed and cared for, these clays will uphold their integrity and maintain their aesthetic appeal.

Working with Chosen Clays

When sculpting with top clays for outdoor use, there are some techniques and requirements to keep in mind for best results:

Chosen kaolin clays are very plastic but can be prone to cracking and shrinking during the drying and firing process. Work carefully to avoid tearing the clay and introduce air bubbles. Let pieces dry slowly and fire using a low temperature kiln technique to minimize shrinkage.

Some stoneware clays can be quite heavy and dense. Sculptures may require an internal armature or support structure. Plan the sculpture design and weight distribution carefully. Remove excess clay from areas that don’t require structural strength.

Use sturdy sculpting tools and avoid delicate edges that may chip. Wear a particle mask when sanding rough surfaces. Smooth any cracks or imperfections before the final firing.

Check manufacturer specifications for proper firing temperatures and soak times. Use a kiln sitter for consistent results. Allow sculptures to cool completely before exposing them to outdoor elements.

Seal finishes thoroughly with an outdoor-rated sealer glaze. Multiple coats will provide better protection. Reapply sealer every few years as needed.

Consider weather-resistant mounting options. Use reinforced concrete bases for freestanding sculptures. Attach wall pieces with stainless steel hardware.

Inspect frequently for signs of damage or wear. Make repairs promptly to avoid larger issues. Handle with care when transporting finished sculptures.

Sculpture Maintenance

Once your outdoor sculpture is complete, maintenance is crucial for preserving it against the elements. Here are some tips for protecting your finished clay sculpture outside:

Apply a sealant or protective coating. Products like varnish, lacquer, wax, or polyurethane are designed to waterproof and protect surfaces. Choose a coating suitable for outdoor use and reapply as needed. This will guard against moisture damage.

Check for cracks or damage after storms. Temperature changes, rain, snow and wind can cause clay to expand and contract, resulting in cracks or chipping. Routinely inspect your sculpture and make repairs as soon as possible.

Consider a covered location or shelter. Placing your sculpture under an overhang or canopy provides some protection from direct sun, rain and snow. This can prolong its life outdoors.

Bring sculptures indoors for winter or move to a protected area. If possible, storing your clay artwork inside a garage or shed during cold weather is ideal to prevent freezing and thawing damage.

Repair any broken pieces using clay slip. Simply moisten the broken edges and press them back together firmly. Fill any gaps with more slip or clay. Allow repairs to dry completely before sealing.

Clean gently. Use a soft cloth dampened with water to remove dirt and debris. Avoid harsh cleaning products or scrubbing that could erode the clay surface.

With proper sealing and routine care, your clay sculpture can last for many years outside. But be prepared to touch up any damage right away to maintain its integrity.

Examples of Famous Works

Some of the most iconic and beloved outdoor sculptures were crafted from durable clays that withstand the elements. Here are a few famous examples:

The Thinker – This iconic bronze sculpture was created by Auguste Rodin in 1880 using clay for the original model. The Thinker has been cast outdoors in multiple locations around the world, with the original on display outside the Musée Rodin in Paris.

The reflective pose and fluid modeling of the clay captures the essence of human contemplation. The scaled up bronze versions hold up well to outdoor environments due to clay’s stability through the casting process.

Mount Rushmore – The colossal presidential busts of Mount Rushmore were sculpted into the rockface of Mount Rushmore National Memorial in South Dakota. Sculptor Gutzon Borglum started with a clay model at 1/12 scale and then hand-carved the 18 meter granite portraits.

The grand scale and intricate detail of the clay design was essential for Borglum to transfer the vision to stone. The granite mountainside protects the sculptures from weathering.

Angel of the North – This iconic 20 meter tall sculpture stands proudly over England’s North East countryside. Sir Antony Gormley crafted the design in clay before casting it in steel.

The clay allowed Gormley to play with forms and involve his team. The steel casting offers durability, while the scale makes a bold statement visible from afar. The Angel has become a symbol of regional pride.

DIY Outdoor Sculpture

Creating your own outdoor sculpture can be a fun and rewarding hobby. Here are some beginner tips to get started:

Choose a Simple Design

Opt for a basic shape like a sphere, cube, cylinder, or abstract form. Complex shapes with thin protrusions are prone to breaking.

Use Air-Dry Clay

Air-dry clays like Crayola Model Magic are inexpensive, easy to work with, and don’t require kiln firing. Make sure to use an outdoor variety.

Create an Armature

Build a simple metal wire, wood, or plastic mesh frame to support the clay. This adds stability to your sculpture.

Work in Sections

Sculpt different clay pieces separately, allowing them to dry fully before assembly. This prevents cracking or collapse.

Smooth and Detail

Use plastic sculpting tools to refine the surface. Add textures, patterns, or designs before allowing to dry fully.

Seal and Protect

Apply an outdoor varnish or sealant like polyurethane to protect from weathering. Reapply yearly.

Display in a Sheltered Spot

Position your sculpture in a covered patio or under an eave. Avoid direct sun and precipitation.

With simple materials and techniques, you can create your own unique outdoor sculpture art for the garden!

Conclusion

When choosing the best clay for outdoor sculpture, durability is key. Clays like stoneware and porcelain that can withstand freezing temperatures, rain, and sun exposure will result in long-lasting outdoor sculptures. Testing different clay bodies by making small test tiles and placing them outdoors for a season is recommended.

Stoneware clays have excellent workability for sculpting and hold fine detail well while being durable outdoors. Porcelain clays are also extremely durable for outdoor use, but can be more challenging to work with and are prone to chipping if very thin. Terra cotta clay is an affordable option but requires a sealer for outdoor use.

Polymer clays make wonderful outdoor sculptures as well when properly prepared and sealed. The future of outdoor sculpting offers even more options, with advances in specialized outdoor clays, sealants, and 3D printing. With the right choice of materials, creative sculptors will continue making museum-quality art for the world to enjoy outdoors.