india ink or what else ?
Posted 20 August 2012 - 09:01 PM
Makes a lot of sense in that setting.
- mregecko likes this
Adjunct Professor of Ceramics; New Hampshire Insitute of Art
Former Guest Professor, Wuxi Institute of Arts and Science, Yixing, China
Former President and Past President; Potters Council
Posted 14 March 2013 - 09:09 AM
Thank you everybody for your answers and suggestions. As Idaho Potter suggests, I should have given you more information about my bowls. They are slip cast with porcelain (so much for raku !!), no glaze on the outside and a beautiful green glaze inside. Looks like a celadon even though it is fired cone 9 oxidation. The cracks lines with india ink are dark, precise, exactly what I am looking for. But India Ink is probably slightly diluted with liquids. Even if it is only a little, I do not want to take the risk. I think the unfired Amaco underglaze is probably just as toxic as India Ink.
Someone here in Switzerland just suggested food colorants. Has anyone tried ?
Thanks for the latin verse but, even though I am french speaking, I'll need a translation. School did not lead me as far as Latin classes.
I have used black food coloring on the exterior, which looked fine but when I used the cup with hot tea, the ink on the outside sweated off. The cracks remained dark but the ink came off on my hands, and this also happened when I washed the cup. It wasn't black black but still a bit messy and disconcerting. Don't know how long it would remain in the cracks this way either. I'm looking for a safe alternative. Shiloh
Posted 14 March 2013 - 02:28 PM
For those who are concerned about their customers this information is from the FDA food code 2009-Cleanability
4-202.11 Food-Contact Surfaces.
The purpose of the requirements for multiuse food-contact surfaces is to ensure that such surfaces are capable of being easily cleaned and accessible for cleaning. Food-contact surfaces that do not meet these requirements provide a potential harbor for foodborne pathogenic organisms. Surfaces which have imperfections such as cracks, chips, or pits allow microorganisms to attach and form biofilms. Once established, these biofilms can release pathogens to food. Biofilms are highly resistant to cleaning and sanitizing efforts.
For completeness and to play devil's advocate, literally millenia of tableware has been used to minimal ill effect, often with cracks, pits, unglazed surfaces, etc...
The FDA food safety code is a very stringent guideline for individuals to protect themselves from liability. As a professional potter selling tableware, yes it is probably best to follow this code for your own liability.
However, the likelihood of this actually happening is extremely small.
I.E. Yes, it is possible, that if you let raw chicken sit in a crackled dish for weeks, you won't be able to wash out all of the bacteria.
But if you're using it for beverages or cooked foods, and cleaning it afterwards, you'll probably be fine. I do it all the time, and so do MANY people I know.
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