Slip casting is one of the most effective methods for reproducing ceramic objects. Once a master model and plaster mould have been created, the same basic form can be cast repeatedly with consistent proportions.

However, casting does not mean that every finished piece must be identical.

At KUST, we use the mould as a foundation for further handwork. After casting, the ceramic form can be reshaped, carved, pierced, combined with other elements, decorated, and glazed in different ways. This allows us to reproduce a successful structure while continuing to develop the design of every object.

Our Eagle Ray ceramic wall lamp is an example of this process. Its creation begins with research and drawing, continues through a plasticine master model and plaster mould, and ends with casting, hand refinement, glazing, firing, and installation of the lighting system.

The mould reproduces the base form. The artist creates its character.

Creating a complex ceramic sculpture entirely by hand may take many hours. Repeating the same structure for every new piece can make the process slow and leave less time for artistic experimentation.

Slip casting solves this problem.

The artist first creates one carefully developed original. A plaster mould is then taken from it and used to reproduce the main volume.

This provides several advantages:

• consistent proportions;
• more predictable wall thickness;
• faster reproduction of complex shapes;
• less time spent rebuilding the same form;
• more opportunities to experiment with decoration and glazing;
• the possibility of producing small collections.

Slip casting is especially useful for smooth sculptural forms, wall objects, ceramic lamps, reliefs, and hollow constructions that would be difficult to recreate accurately by hand each time.

Casting can be used in two different ways.

In industrial production, the cast form is usually treated as a finished standard. Every object is cleaned, glazed, and fired according to the same process.

In artistic ceramics, casting can be only the first stage.

Once the form is removed from the mould, the artist can:

• change its curvature;
• cut or reshape the edges;
• add hand-built details;
• combine several cast components;
• carve lines and textures;
• create openings for light;
• apply different colours, glazes, and surface effects.

This is an ideal approach to product development. The main form remains consistent, while each new cast can become a design experiment.

One ray may have a dense pattern of light openings. Another may have carved lines or a completely different glaze. Several cast elements may also be combined into a larger sculptural composition.

The mould accelerates repetition without limiting creativity.

Casting can be used in two different ways.

In industrial production, the cast form is usually treated as a finished standard. Every object is cleaned, glazed, and fired according to the same process.

In artistic ceramics, casting can be only the first stage.

Once the form is removed from the mould, the artist can:

• change its curvature;
• cut or reshape the edges;
• add hand-built details;
• combine several cast components;
• carve lines and textures;
• create openings for light;
• apply different colours, glazes, and surface effects.

This is an ideal approach to product development. The main form remains consistent, while each new cast can become a design experiment.

One ray may have a dense pattern of light openings. Another may have carved lines or a completely different glaze. Several cast elements may also be combined into a larger sculptural composition.

The mould accelerates repetition without limiting creativity.

3. Creating the Master Model

Before making a plaster mould, the artist creates a master model.

The process usually begins with references and sketches. For the Eagle Ray lamp, we study the animal’s anatomy, movement, and characteristic silhouette. The goal is not necessarily to create a scientific copy, but to understand which features make the ray recognisable.

A paper template helps establish the final dimensions and proportions.

Because the object will function as a wall lamp, the design must also consider:

• the position of the light source;
• the distance between the ceramic body and the wall;
• the location of light openings;
• the mounting system;
• the weight of the finished object;
• access to electrical components.

The master model is then built from plasticine.

Plasticine is well suited to this process because it does not dry. It can be added, removed, smoothed, and reshaped until the proportions are correct.

The artist begins with the main volume and silhouette before adding small details. At the same time, the model must be designed so that it can be removed from the future mould. Deep undercuts and extremely thin elements may make casting difficult or require a multi-part mould.

The quality of the master model determines the quality of every future cast.

4. Making the Plaster Mould

Plaster is used for slip casting because it is porous.

When liquid clay touches the plaster surface, the mould absorbs water from the slip. Clay particles remain inside and gradually create a solid wall.

The type of mould depends on the shape of the object. A wall sculpture or relief may require a simple open mould, while a complex three-dimensional form may need several parts.

Before pouring plaster, the artist must determine:

• the mould division lines;
• the direction in which each section will open;
• the position of the pouring opening;
• whether the model contains undercuts;
• how the final cast will be removed safely.

Once the plaster has hardened, the plasticine model is removed and the mould is dried thoroughly.

A dry mould absorbs moisture more effectively and creates a more predictable ceramic wall.

5. Casting with Slip

Slip is liquid clay formulated specifically for casting. It should flow easily while still containing a high percentage of clay particles.

Before casting, the slip must be mixed thoroughly and checked for lumps or settled material.

It is then poured or distributed inside the plaster mould. As the plaster absorbs water, a ceramic layer forms along the surface.

For closed forms, the remaining liquid slip is poured out after the required wall thickness has developed. For open wall sculptures, the slip may be applied in controlled layers.

Wall thickness is important.

A wall that is too thin may tear or break. A wall that is too thick becomes heavy, dries unevenly, and may crack or deform.

Casting time depends on the size of the object, the condition of the mould, the slip formulation, and the temperature and humidity of the studio.

Once the clay has stiffened and begun to shrink slightly away from the plaster, the cast can be carefully removed.

6. Refining the Cast by Hand

Removing the form from the mould does not complete the object.

This is where individual handwork begins.

Mould seams and excess clay are removed. The edges are refined, minor defects are repaired, and the silhouette is adjusted.

The artist may also:

• add sculpted elements;
• combine separate cast parts;
• carve relief;
• create surface textures;
• pierce holes;
• change the position or curvature of the form.

For the Eagle Ray lamp, the openings across the ceramic body are created individually. Their arrangement influences both the appearance of the sculpture and the light pattern it produces on the wall.

This handwork ensures that even pieces created from the same mould retain individual differences.

7. Drying and Firing

After refinement, the cast must dry slowly and evenly.

Slip-cast objects may appear dry on the outside while still containing moisture in thicker areas. Uneven drying can lead to warping or cracking.

Large, curved, or wing-like forms should be supported carefully while the clay remains soft.

Once fully dry, the object undergoes its first kiln firing. Bisque firing transforms the fragile dry clay into a permanent ceramic body that can be safely handled and glazed.

The firing temperature depends on the casting body and the intended glaze system.

8. Choosing the Glaze and Decorative Technique

Glaze selection involves more than choosing a colour.

The glaze must be compatible with the clay body and firing temperature. It must also support the form and artistic concept of the object.

The same cast can look completely different depending on the finish:

• glossy or matte;
• smooth or textured;
• monochrome or layered;
• dark and reflective or light and natural;
• evenly coloured or reactive.

Glazes can be brushed, poured, dipped, layered, or sprayed.

For sculptural lamps with many openings, spraying can create a more controlled surface without filling small details with too much glaze.

The final result depends on the clay colour, glaze thickness, firing temperature, kiln atmosphere, and cooling process. For this reason, new glaze combinations should always be tested before they are applied to a finished sculpture.

Artistic and Industrial Casting

Slip casting is also widely used in factories.

Industrial production relies on precise moulds to create large quantities of nearly identical objects. Standardised processes reduce labour and allow the cost of developing the model and mould to be divided across thousands of pieces.

This makes ceramic products more affordable and accessible.

The trade-off is that the individual object usually loses its uniqueness. Its purpose is to match every other unit as closely as possible.

Artistic casting follows a different principle.

The main form may be repeated, but the artist continues working after the object leaves the mould. Hand-built details, textures, openings, glaze combinations, and firing effects give each piece an individual character.

Industrial casting uses the mould to achieve standardisation.

Artistic casting uses the mould to create space for variation.

Conclusion

Slip casting is not simply a method for copying ceramic objects. It is a bridge between sculpture, design, and production.

The process begins with an idea and a carefully developed master model. A plaster mould preserves the successful form, while liquid clay makes it possible to reproduce it efficiently.

After casting, the artist can continue refining, combining, decorating, and transforming the object by hand.

When used thoughtfully, casting does not replace creativity. It saves time during repetitive structural work and creates more opportunities for artistic development.

The mould preserves the form.

The hands develop the design.