Introduction: Burn-outs: Reusing Fibers in Clay and Glass
Burn-out process:
Up-Cycle. From the ceramic process of burning out; binders of organic material coated with porcelain casting slip, creates an exoskeleton or shell in the kiln when ceramic vitrification is reached. Reusing organic plants, shearing, or even polyurethane foam, combined with either clay or glass, creates a atmospheric firing which results in a porous lightweight material.
Results:
- Fiber burns to leave behind an external shell
- Glass color varies based on fiber tone, cracking, crawling, and other surfaces result.
- Casts with high fiber count hold shape and collects more binder material
- Porous, lightweight, and fragile
Step 1: Clay and Glass Materials:
Materials:
- Clay Temperature Range: 2232 F
- Glass Temperature Range: 1345-1410 F
Clay and glass temperatures, materiality and workability have similar qualities, which allows the firing process to be interchangeable. Results vary based on color reactions and kiln atmosphere. The organic body during the burn-out cycle (400-600 F) creates an inner shell which hollows out to a porous state similar in weight and fragility.
Step 2: Technical Forming:
- Tools: Using your hands as the main tool, a mold for the structure and shaping, and finally a kiln for firing.
- Formulas: The glass formula is a basic ratio of water-aloe-glass-fiber based on the mold size and can be customized based on the casting wall thickness. The clay formula of the porcelain casting slip is a cone 6 porcelain and the glass is Bullseye powder.
- Molds: Use 50% Plaster and 50% Silica basic mold formula or fire shield plaster board (drywall) for release.
- Kilns: Gas (Blaauw) or electric kilns (Paragon) require an up-draft ventilation system or top vent hood. Safety respirators are required during off-gasing temperature between 500-1500 degrees F. Any soft brick will be impregnated with the release of cellulose fibers and carbon during this firing. Kiln should be fired after for a clean out cycle to release the rest the imbedded fumes, otherwise devitrification and discoloration will occur.
Step 3: Slip Casting:
Process: Combine organic fiber material, soak/dip multiple times in cone 6 porcelain slip until a 3-5 mm shell hardens over to dry.
- Dry time: 12-24 hours, then applied choice of underglaze/ cone 6 glaze 3.
- Kiln Furniture: Stilt in kiln, fire on fire shield plaster board, or apply casting sand as a release (Note: off-gasing of material could potentially harm kiln shelf).
- Kiln Schedule: Fire to cone vitrification temperature, unplug vent holes, and redirect fumes with heavy ventilation.
*Unload and clean kiln, followed by a neutralizing clean out firing - 1300 F, 2-4 hr hold to vent.
Step 4: Glass Molds:
Process: Combine organic fiber material with Op. Bullseye glass powder until a 2-3 mm shell hardens over to dry.
- Mold: 50% plaster and 50% silica frosted mold forms
- Glass formula: 1/4 cup Water, 1 cup 100% Aloe, 6-12 tbs. of Bullseye (Kugler, Riechenbach, Gaffer) glass powder, then mixed with fiber until it becomes a slip consistency. Pack into bowl to dry and form to shape.
- Allow 4-7 days to dry
- Kiln furniture: Fired in mold with casting sand on shelf or flat on fire shield plaster board as release (Note: off-gasing of material could potentially harm kiln shelf).
- Fire to tack fuse temperature (1300-1375 F) with both vents, followed by a neutralizing clean out firing - 1300 F, 2-4 hr hold to vent.
Step 5: Results:
Ceramic:
- Organic/Nonorganic fibers vary in shrinkage
- Polyurethane fiber without glaze holds shape with little slumping or warping
- Glaze helps with structural quality
- Sculptural capabilites
Glass:
- Glass color varies based on fiber tone, cracking, crawling, and other surfaces result.
- Casts with high fiber count hold shape and collects more binder material
- Porous, lightweight
- Functional/sculptural capabilities