This piece was slipcast using Ashraf Hanna stonware clay and after bisque firing was coated with Ferric Chloride. Whilst still wet, various oxides and carbonates were sprinkled over the surface of the main body.
 
The body was then wrapped in aluminium foil and fired in a raku kiln to 850°c. Once temperature was reached the piece was removed from the kiln and once safe to handle, the foil was removed and the piece was left to cool in the open air.
 
Once cool it was cleaned up and vegan and eco friendly wax was used to buff the surface to a shine.The top was hand blown out of black glass with a clear glass coating.
 
The top was blown by glass artist James Maskrey under my direction. Sadly I cannot take credit for this!
 
What is Raku Saggar Firing?
 
Raku Firing: Raku is a traditional Japanese firing technique characterized by its fast firing and cooling processes, which result in unique and often unpredictable surface effects.
 
Saggar Firing: Involves placing pottery inside a protective container (saggar) during firing to shield it from direct flame and kiln atmosphere, allowing for controlled fuming and colouring using various organic and inorganic materials.
 
Ferric Chloride in Saggar Firing
 
Ferric chloride (FeCl3) is a chemical compound used in saggar firing to produce vibrant colours and patterns on the surface of ceramics. When used in raku saggar firing, ferric chloride vaporizes and interacts with the clay body to create distinct effects. It also produces chlorine gas so great care must be taken when firing with Ferric Chloride.
 
The Process of Raku Saggar Firing with Ferric Chloride
 
Preparing the Pottery:
The pottery is usually bisque-fired before undergoing this type of raku saggar firing process.
The pieces are often burnished or coated with terra sigillata - a fine grade slip - to create a smooth surface that will better capture the effects of the ferric chloride fumes.
 
Applying Ferric Chloride:
Ferric chloride can be applied to the pottery using a brush, spray bottle, or other methods. It is often diluted with water to control the concentration and effect. The application should be done in a well-ventilated area, and safety precautions, including gloves and masks, should be taken due to the chemical’s caustic nature.
 
Preparing the Saggar:
The pottery is placed inside a saggar (wrapped in aluminium foil) along with various combustible materials such as sawdust, seaweed, salts, and organic materials. These materials contribute to the fuming process, adding to the surface effects created by the ferric chloride.
 
Firing Process:
The saggar is placed inside a raku kiln and fired. The firing temperature for raku saggar firing typically ranges from 1,500 to 1,800 degrees Fahrenheit (815 to 980 degrees Celsius). During firing, the ferric chloride vaporizes, and its fumes react with the clay body, producing various colours, including shades of yellow, red, orange, and brown. Common effects include mottled or marbled surfaces with rich, earthy hues.
 
NB: The heating of Ferric Chloride can and usually will produce chlorine gas so an appropriate respirator must be worn. 
 
Reduction and Cooling:
After reaching the desired temperature, the saggar and its contents are removed from the kiln. The cooling process can be done in open air and the saggar opened once safe to touch using heat proof gloves.  The rapid cooling process can enhance the visual effects created by the ferric chloride and other fuming materials.
 
The technique creates visually stunning and one-of-a-kind pieces with complex surface patterns and colors that are difficult to achieve through other methods.  Potters can experiment with different combinations of materials, firing temperatures, and application methods to achieve a wide range of effects, allowing for significant creative expression.
 
Safety: Handling ferric chloride requires careful attention to safety protocols due to its caustic nature. Proper ventilation, protective clothing, and safety gear are essential.
 
Durability: Like other raku-fired pieces, pottery created using this method is generally more porous and less durable than high-fired ceramics. These pieces are often best suited for decorative rather than functional use.