Encapsulated Stains
These stains can strongly pigment a glaze in amounts as low as 10% (if everything is right, see below). Many companies that hesitated to use these stains in the past now use them in their biggest selling products.
Encapsulated stains are not, as the name suggests and some misunderstand, a zircon capsule around an otherwise unstable compound. Rather, they are manufactured by sintering to form a crystalline matrix (in a process called encapsulation). After sintering they are ground, filter pressed and dried. In cadmium encapsulated stains, for example, the matrix between the zircon and cadmium is stable to 1220C and the selenide/selenium is released during combination. The stain is further rendered safer-to-use by washing with water or weak acid to remove any soluble uncombined compounds (e.g. cadmium or soluble impurities). This washing process does produce toxic byproducts that can only be tolerated in certain countries (e.g. India, China).
Manufacturers have specific recommendations for each stain that must be followed closely. For example, cadmium stains normally work best when glazes are slow cooled and many must be used in glazes with a qualifying chemistry (e.g. glazes for cadmium stains must have no zinc (affects color), no titanium (crystallizes and makes the color fuzzy, a little TiO2 in the clay is tolerable) and have low alumina. Obviously, these stains must not be ball milled, glazes must be milled prior to adding the stain. Suppliers may hesitate to publish some specifics that might give away trade secrets of their products, even relating to the chemistry requirements in host glazes. Generally detailed testing is needed to establish a firing curve and a compatible host glaze to get the best possible color.
The crystalline compound created must not be fired above its recommended temperature or the normally toxic compound will dissolve into the glaze (normally without volatilization unless the maximum temperature is greatly exceeded) and the color will be lost and the glaze rendered toxic. Cadmium content and cadmium release are separate issues. The manufacturing process of these stains is designed to create a stable coloring zircon-compound from a parent metal that would otherwise be unstable (e.g. leachable toxicity). Metal release tests must be done to monitor metal release.
Other kinds of encapsulated stains besides cadmium are: Zircon Pr Yellow, Zircon Vanadium turquoise, Zircon Iron Coral, Zircon Vanadium Orange, Zircon Pr/Vanadium Green. The color depends on the sintering temperature.
Out Bound Links
In Bound Links
| 
- 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.
Learn more.. |
