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  1. Thanks, I will try the food colouring. But in case someone else is interested I received a suggestion via a teacher here in Geneva : blacken the cracks with a black stain et fire again at "gold" temperature. Sounds like a good suggestion, no ?
  2. Just the other day I saw a YouTube video; the Asian artist uses 'india' or 'china' ink, but also uses food coloring for safety.<div>You might google 'india' ink for some formulation info. I suspect it is still- after several millennia- a pretty primitive concoction. Plus, the amount one might ingest is infinitesimal- worry more about the quality of the water used to prepare the food and drink!</div>
  3. 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.
  4. I have been working with crackle glazes for a long time but never on fonctional pieces. I have always coloured the cracks with India ink but I know it is not very good for your health. I have tried iron oxyde but it only works on very pale glazes. I have also tried cuttlefish ink but it does not work. Any idea as to what I could use to obtain black lines and not poison my customers ? I would be grateful if someone can help me.
  5. Ok, There shouldn't be a problem then with 2 tablespoons. Keep in mind like the bleach you'll need to add more from time to time. Thanks. Will try!
  6. On my side of the world, gallons are liters... but yes my buckets are - if I count right - approximately 5 gallons.
  7. Thank you Andy. I know nothing about hydrogen peroxide. Can you tell me an approximate percentage ? Does it alter in any way the quality of the clay ? Does it require wearing gloves ?
  8. Thank you Marcia. I have tried bleach. It works a couple of days but then the smell takes over. The idea is to let the clays sit as long as the buckets are not full. When they are full, I spend half a day dealing with all the clays that need to be recycled. Otherwise I spend too much time and use too much space dealing with small amounts of used clays. The problem is particularly strong with porcelain and very fine stoneware (without grog.)
  9. Does anyone have an idea how to avoid clays that have to sit for a long time in buckets. I have of course covered the buckets. i have tried lavender. But some clays really develop an awful smell i no time at all.
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