Ovenware
Ovenware clay bodies have a lower thermal expansion than typical bodies so they can withstand more sudden changes in temperature without cracking. Flameware bodies are not the same, they can withstand an open flame and demand much more compromise in working properties, strength, glaze fit, etc.
While many potters make ware for use in the oven using standard clay bodies, ovenware manufacturers would object to calling this 'ovenware' since they dedicate considerable resources to producing low expansion bodies and matching glazes. Still, potters have found ways to get away with using standard bodies and glazes by making sure glazes fit well (no crazing), avoiding high-quartz and highly vitreous bodies, firing evenly to reduce built-in stresses, maintaining an even ware cross section, avoiding angular contours and larger sizes with broad flat bottoms and telling customers to be careful about subjecting ware to sudden temperature change.
Glaze fit is a major problem in designing an ovenware body since common glazes will craze. It is much easier to make a low expansion clay body than a glaze, thus it is normal to compromise the lowest possible expansion on the body in order to get a reliable glaze fit.
There are main two mechanisms for creating a low expansion body: By firing to form a crystalline matrix that has low expansion (e.g. Corningware) or by employing materials having particles of low expansion (e.g. mullite, pyrophyllite, petalite and kyanite) and formulating and firing in such a way that these particles are not altered. The former produces a more vitreous body and requires much more expertise and test equipment. As noted, the later is a bit of a 'crowbar' approach and is dependent on not firing to full maturity (otherwise mineral species can be dissolved by the feldspar in the body or simply altered in crystal form and the low expansion effect is lost). This can create a bit of a 'tug-of-war' in the body since the glass that glues all the particles into a matrix will likely have a higher expansion. Obviously, ovenware bodies should have much lower free quartz content, especially the larger particle sizes, since these have very high thermal expansion. This does not just mean avoiding only ground silica, ball clays also contribute alot of quartz.
Pottery ovenwares are typically made using a high percentage of spodumene (30%) along with some feldspar and pyrophyllite (about 10% of each) and a mix of ball clay and kaolin or stoneware clays. Glazes can be made using recipes with lots of MgO and bone ash and low KNaO.
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- Login to a private account or work with others in a group account (e.g. university).
- Nothing to install (access it using your web browser). It is always the latest version.
- Easy to import your existing data.
- As many side-by-side recipes as you want.
- Many ways to search and classify glaze and body recipes.
- Glaze and body recipes are robust, with units-of-measure, unlimited pictures with individual titles and descriptions.
- Add variations to a recipe; each with its own pictures, descriptions and name/code-number extensions.
- Recipes can link to typecodes, projects and firing schedules (all managed in their own areas).
- Standard reports and mix ticket reports with last-minute-totalling; variations report as if they are a complete recipe.
- Video tutorials, help system, contact form on every page, dedicated messaging and support ticket systems.
- It is an industrial-strength database system (unlimited capacity, fast, reliable, scalable).
Imports many file formats
- Glaze recipe formats supported: HyperGlaze, GlazeGhem, GlazeMaster, Matrix, INSIGHT XML recipes (single and multiple), INSIGHT SQLite DB files.
- Assign a batch number to imports, and later search by batch.
- Assign multiple typecodes to imported glaze and body batches (to classify) and search on these later.
- Prepend character sequences to glaze recipe names during import.
- Import the pictures and pair them to their corresponding records automatically.
- One click to automatically export the database to an SQLite DB database file and download it (for use with desktop INSIGHT or just as a backup).
- Export and import individual glaze recipes as text or XML.
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