9.6: Troubleshooting
- Page ID
- 299322
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Overview of Kiln Firing
1. Uneven Temperatures Within Kiln: Use witness cones throughout the kiln to monitor temperature variances and adjust loading strategies.
2. Overfiring: Regularly calibrate kiln thermocouples and timers to ensure accurate firing schedules.
Bisque Firing: Purpose and Process
1. Cracking During Bisque Firing: Ensure pieces are completely dry before loading them into the kiln. Preheat the kiln slowly if necessary.
2. Pieces Sticking to Kiln Shelf: Use kiln wash on shelves and avoid placing pieces directly on the shelf where possible.
Glaze Firing: Understanding Temperatures and Atmospheres
1. Glaze Not Maturing: Verify the match between the glaze maturity range and the kiln's firing temperature.
2. Discoloration: Adjust the firing atmosphere (oxidation or reduction) based on the glaze's requirements for color development.
Special Firing Techniques: Pit, Salt, and Wood Firing
1. Unpredictable Results: Embrace the variability inherent in these methods. Experiment with placement and materials to influence outcomes.
2. Safety Concerns: Follow all safety protocols, especially for salt and wood firings, to manage fumes and fire risk.
Uneven Temperatures Within the Kiln
- Problem: Inconsistent heating can result in uneven glaze maturation, warping, or color differences across pieces.
- Solution: Use witness cones at various levels and locations within the kiln to identify hot and cold spots. Adjust the kiln load by spacing pieces evenly and avoiding overloading shelves.
- Tip: Experiment with baffle plates or kiln furniture arrangements to redirect airflow and improve heat distribution.
- Prevention: Regularly check and maintain kiln elements or burners to ensure they are functioning optimally.
Over-firing
- Problem: Over-firing can cause glazes to run excessively, clay bodies to warp, or pieces to fuse to shelves.
- Solution: Calibrate thermocouples regularly to ensure accurate temperature readings. Use pyrometric cones to monitor actual heatwork.
- Tip: Fire test pieces with new glaze recipes to verify their maturation range before applying them to finished work.
- Prevention: Double-check your firing schedule and ensure you don’t exceed the recommended temperature for your materials.
Cracking During Bisque Firing
- Problem: Rapid heating or residual moisture in greenware can cause cracks during bisque firing.
- Solution: Allow pieces to dry completely before loading the kiln. Use a slow preheating cycle to drive out remaining moisture.
- Tip: For thick or complex pieces, preheat the kiln at a low temperature (200–250°F/90–120°C) for several hours.
- Prevention: Monitor the drying environment to ensure even drying, avoiding drafts or overly humid conditions.
Pieces Sticking to the Kiln Shelf
- Problem: Glaze drips or improper use of kiln wash can cause pieces to stick to shelves during firing.
- Solution: Apply a fresh, even layer of kiln wash to shelves before firing. Use stilts for glazed bottoms or place catch plates under heavily glazed pieces.
- Tip: Sand down and reapply kiln wash to damaged areas before the next firing to maintain a smooth surface.
- Prevention: Avoid applying glaze too close to the bottom edge of pieces, and ensure shelves are clean before loading.
Glaze Not Maturing
- Problem: Glazes appear dull, rough, or under-fired if they don’t reach their target temperature.
- Solution: Verify the glaze’s firing range and adjust the kiln schedule as needed. Ensure that thermocouples are accurate and pyrometric cones are used.
- Tip: Fire test tiles with different ramp rates and holds to fine-tune the firing cycle for specific glazes.
- Prevention: Regularly inspect kiln components, especially in gas or wood kilns, where temperature fluctuations are more common.
Discoloration
- Problem: Unexpected colors in glazes can result from improper firing atmospheres, contamination, or material inconsistencies.
- Solution: Ensure the firing atmosphere matches the glaze recipe’s requirements (oxidation or reduction). Clean tools and equipment to avoid cross-contamination.
- Tip: Test raw materials in small batches to identify any inconsistencies in purchased supplies.
- Prevention: Store materials in labeled, sealed containers to prevent accidental mixing.
Unpredictable Results in Alternative Firings
- Problem: Pit, salt, and wood firings often produce inconsistent or undesired results due to their dynamic nature.
- Solution: Document firing conditions thoroughly, including placement, materials, and timing, to identify patterns and refine techniques.
- Tip: Experiment with different materials, such as oxides or organic inclusions, to achieve desired effects.
- Prevention: Embrace unpredictability as part of the process and plan for some pieces to serve as learning experiences.
Safety Concerns in Alternative Firings
- Problem: Open flames, toxic fumes, or uncontrolled firing conditions can pose risks in pit, salt, or wood firings.
- Solution: Conduct firings outdoors in well-ventilated areas, and have fire extinguishers or water sources on hand. Wear appropriate protective gear, including gloves, goggles, and masks.
- Tip: Inform neighbors or local authorities if firing in residential areas to avoid conflicts or misunderstandings.
- Prevention: Follow established safety protocols and work with experienced artists to ensure proper handling of firing techniques.
The firing process is a blend of science, art, and careful planning, transforming raw materials into finished ceramics. By understanding kiln types, firing atmospheres, and the stages of firing, artists can refine their work and achieve consistent, high-quality results. Troubleshooting common issues ensures a smoother firing process, while alternative methods like pit, salt, and wood firing provide opportunities for creative exploration. With proper preparation, documentation, and safety practices, the magic of firing becomes a reliable and rewarding part of the ceramic journey.