The Effects of Miracle-Gro on Pit Fired Pottery

Miracle-Gro not only can be used for fertilizing plants but also for pit-firing pottery. This process produces an unglazed, extremely porous style of pottery that is fired, or baked, in a pit surrounded by coals and ash. This firing treatment creates unusual colors and patinas, depending upon the mineral or chemical additives placed in the pit during the firing process.

The Process & Color

Once a pot has been made it is coated in a liquid clay to seal the surface. The unfired pot is placed in a bed of fine sawdust that is sprinkled with salt and other minerals and metals. This is where Miracle-Gro plays a role. Among the minerals and metals Miracle-Gro contains are copper carbonate and aluminum phosphate. These can produce colors ranging from red to blue and green. The small amount of salt not only assists with with color development but also can react with other minerals to create effects and designs. Wood is then placed on top of the pottery and set aflame. Temperatures reach a maximum of 1,500 degrees, which makes this a slow-firing technique that requires up to 15 hours. Once the fire has burned out and the pots are cool enough to handle, they are removed from the ashes, cleaned and sealed so colors remain vivid.

Carbon Trapping

Carbon trapping is produced by the combination of ash, smoke and sawdust. The process creates surface effects. When Miracle-Gro is applied to the pottery surface and then covered in a layer of sawdust, the Miracle-Gro adheres to the pot and burns off during the firing process. The effect is a dark black coloring on the surface of the pottery.

Carbon Fuming

Color fuming is achieved when the material being burned is soaked in a mineral compound. In this process, Miracle-Gro is mixed with water and the material being burned (wood) is soaked in the solution, allowed to dry and packed around the pottery. As the material burns, the fumes generate a smoky effect to the pottery surface.