2.4: Understanding Kilns- Types and Uses
- Page ID
- 278071
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Kilns: The Heart of the Studio
- Electric Kilns:
Electric kilns are the most common choice for beginner and home studios due to their reliability and ease of use. They are powered by electricity and controlled by a digital or manual controller to regulate temperature. Beginners can experiment with consistent results using electric kilns, making them great for learning. Ensure the kiln is on a dedicated circuit to avoid electrical overloads.
- Gas Kilns:
Gas kilns require a propane or natural gas source, making them suitable for studios with outdoor space. They allow for reduction firing, which removes oxygen during the firing process to create unique glaze effects. Operating a gas kiln requires additional safety precautions and experience. Always have a carbon monoxide detector nearby when firing indoors or semi-enclosed areas.
Firing Cycles
- Bisque Firing:
The bisque firing hardens the clay enough to handle but leaves it porous to absorb glaze. Typically fired at 1,800°F, it removes moisture and organic material from the clay. Always ensure your pieces are completely dry before bisque firing to prevent explosions from trapped water vapor. Use pyrometric cones to confirm the kiln has reached the correct temperature.
- Glaze Firing:
Glaze firing involves applying glaze to bisque-fired pieces, then firing them at a higher temperature. The heat melts the glaze into a glassy coating, sealing the surface. Be careful to leave a clean foot (the bottom of your piece) to prevent it from sticking to the kiln shelf. Kiln wash, a protective coating on shelves, helps prevent permanent damage if glaze drips.
Kiln Safety Protocols
- Never overload the kiln:
Pieces that are too close together can restrict airflow, leading to uneven firing. Leave at least one inch of space between pieces and the kiln walls. Overloading can also increase the risk of thermal shock, which causes cracking. Always use kiln posts and shelves to create multiple levels for efficient loading.
By elaborating each concept, beginners can better understand not only the "what" and "how" but also the "why" behind studio setup and ceramic processes. This foundational knowledge ensures a safer, more efficient, and enjoyable studio experience.
Kiln Maintenance and Troubleshooting
- Regular Inspections:
Kilns are durable but require regular inspections to ensure they function safely and effectively. Check the elements (the heating coils in an electric kiln) for signs of wear, such as thinning or breaking. Cracked kiln shelves or posts should be replaced to prevent uneven firings or collapse during a cycle. Keep a maintenance log to track repairs and ensure timely replacements.
- Kiln Cleaning:
A clean kiln performs better and lasts longer. Remove glaze drips from kiln shelves using a chisel or grinder, but always wear protective gear to avoid inhaling dust. Sweep or vacuum out debris between firings to prevent contamination of your pieces. Use kiln wash (a protective coating) on shelves and posts to protect them from glaze drips during firing.
- Troubleshooting Misfires:
Misfires can happen due to improper programming, electrical issues, or overloading the kiln. If a kiln fails to reach temperature, check the thermocouple (the device that measures heat inside the kiln) for damage or misalignment. Double-check firing schedules in the kiln's controller to ensure you’ve selected the correct program. If misfires persist, consult the kiln manual or seek professional repair services.
- Safety First:
Never leave a kiln unattended during the critical stages of firing. If using a manual kiln, monitor the temperature manually with pyrometric cones to ensure accuracy. Always unplug the kiln or turn off the gas supply before performing any maintenance. Invest in a kiln vent system to safely expel harmful fumes, particularly from glazes containing lead or sulfur.