|Saggar Firing with Aluminum Foil|
|For a quick and easy variation on saggar firing, Barnes now prefers an aluminum foil “saggar.” He paints each pot with ferric chloride (sold as etching solution for printed circuit boards) using a cheap foam brush, rotating it on an inexpensive banding wheel with a plastic top as he brushes it on. Other potters spray this material using an inexpensive spray gun. Inexpensive isemphasized, as ferric chloride is caustic and toxic. It will ruin good brushes, eat away at metal parts on a spray gun, and corrode your metal banding wheel if it comes into contact with it. If you choose to spray ferric chloride, you must wear gloves, goggles and a face mask and spray in a well-ventilated area. Despite all these serious disclaimers, ferric chloride is fairly commonly used because it reliably yields spectacular pink to orange colors.After all the pots are coated with the ferric chloride, Barnes mixes up the same swamp juice in a shallow bowl with just enough water to make the mixture froth. Once this has bubbled up and increased in volume he touches the pot to the bubbling mass. This leaves a lacy deposit on the surface where it contacts the pot. The swamp juice can also be brushed or splashed onto the pot. The saggar is made with foil that has been crinkled up and then spread back out. He scatters a little coarse steel wool, raw cotton and wood chips on the foil. Next he places moistened seaweed over these materials. Copper wire or pieces of copper dish scrubber can also be added to the mix. Next the pot is placed, usually top down, onto all these items.More seaweed, cotton, wood chips and steel wool are then placed over the pot. Finally, the foil is wrapped around to cover the pot and pressed into close contact. The operative words here are “a little” of each of these materials — too much combustible material can result in solid black pots if the foil doesn’t burn away.
The pots are tumble-stacked in a kiln and fired to 1260 degrees F (680 degrees C – about cone 017), at which point much of the foil will have vaporized. It is important to do this outside away from people and homes! Ferric chloride and the other materials will create very toxic smoke as they burn.
Description Engobes can be defined as liquid clay slips of varying compositions which are applied to the surface of a clay object, e.g. a pot. The purpose of the engobe can be as different as the varied forms it comes in: to give color to a piece; to improve the surface texture; to provide a ground to do further decoration on; to add textures. Engobes can be applied to wet clay surfaces, leather-hard ware, greenware and even bisqued wares. In each case the engobe’s shrinkage rate should match that of the clay underneath, otherwise cracking (when the engobe shrinks more than the clay underneath) or shivering (when the clay underneath shrinks more than the engobe on top) can occur. While there are some basic engobe recipes around, The Potter’s Complete Book of Clay and Glazes by James Chappel has a range of engobe recipes for diferent grades of moisture content and firing ranges from cone 10 up to cone 11