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bobzchemist

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  1. An "office" Kiln

    If you must be creative with your pottery at the office, probably the least messy and least dangerous step of making pottery would be glazing bisque-fired pots. A few (dozen) containers of glaze, a banding wheel, and a few paintbrushes should give you access to enough creativity without endangering everyone around you.
  2. Luca, 1) Regarding the iron oxides - saying that the earthenware is porous means that it has pores (holes) and channels in the clay. The purpose of the iron oxide coating would be two-fold - it would reduce the porosity of the earthenware by physically filling the exterior pores, and it would impart color. This could be sealed onto your piece by a wax coating (if you apply the iron oxide after firing), or could be incorporated into the clay body by applying an iron oxide dispersion to your greenware. Applying the oxides after firing would give you greater control over the color. Because it's just a surface coating, It shouldn't affect the acoustics too badly. BASF makes high-end iron oxides (also referred to as "transparent" iron oxides) http://www.basf.com/group/corporate/en/brand/SICOTRANS and so does Rockwood http://www.rpigments.com/Products, to name just a few suppliers. 2) Wax does not have to be dissolved into nasty-smelling solvents. It's just usually done that way because those solvents are cheaper. Talk to the folks at Koster Keunen for information on waxes, natural waxes and possible suppliers of wax/solvent mixtures http://kosterkeunen.com 3) Burnishing pottery does the same sort of thing I was suggesting with the iron oxides - superfine particles seal the surface and fill the pores - but in this case they're clay (terra sigilata). Of course, there's more to it than that: http://ceramicartsdaily.org/pottery-making-techniques/ceramic-decorating-techniques/going-low-tech-a-step-by-step-guide-to-burnishing-pottery/ http://ceramicartsdaily.org/pottery-making-techniques/ceramic-decorating-techniques/make-your-pottery-shine-without-glaze-sumi-von-dassow-explains-the-basics-of-burnishing-pottery/
  3. As a cosmetic chemist, I have worked with iron oxides professionally for a long, long time. As a potter, I've only tried incorporating them in my work recently, so I can say that a buff/brown color is definitely achievable (but may take some work to develop). Using an iron oxide wash made with the micronized, sub-micron, or even nanoparticle size oxides used in high-end cosmetics (much, much smaller than commercial iron oxide washes) should allow the iron oxide particles to seal up some or all of the porosity of the outside surface of the bisqueware without affecting the acoustic properties or strength of the clay instrument. A pleasing variation in exterior color could be achieved by either brushing or spraying a somewhat variable combination of oxides onto each piece. Restricting the porosity should reduce the oil-absorbency you are concerned with. Depending on how high you wind up firing these objects, burnishing the outside surfaces might also work (although I don't believe burnishing would lend itself easily to mass production) Let me know if you want sources of supply for these specialized oxides. Bob Zonis
  4. Refillable Marking Pen

    These might work, if you're comfortable hand-refilling cartridges with a syringe: http://www.jetpens.com/Pilot-Parallel-Calligraphy-Pen-2.4-mm-Nib-Width/pd/894 I'm not sure how well these will write on clay. Or you can use these, that are more widely available (and easier to rinse out): http://www.jetpens.com/Pentel-Aquash-Waterbrush-Pen-Large/pd/1772 http://www.jetpens.com/Kuretake-Waterbrush-Pen-Medium-Compact-Size/pd/2678 http://www.jetpens.com/Sakura-Koi-Waterbrush-Pen-Large-8-Nib/pd/3129 http://www.amazon.com/s/ref=a9_sc_1?rh=i%3Aaps%2Ck%3Awaterbrush+pen&keywords=waterbrush+pen&ie=UTF8&qid=1373467398 The particle size of the iron oxide in ceramic iron oxide washes is so large that it will clog the tips of most refillable markers. The effort involved in finding and testing micro-particle size iron oxide is probably not worth it. (I used to work for the company that makes Sharpie markers)
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