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#11
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Crazing
Hi Xtra News, all very interesting. I think the items you unearthed
tend to direct us towards sensible caution and precautions but for the sake of 'the public at large' those who sell their wares for use with food must be even more cautious. Enough said, I hope. Andy |
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#12
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Crazing
On Fri, 25 Nov 2005 14:30:35 +1300, "Xtra News"
wrote: Well I decided to do a bit more looking into this, Well, I'm not sure what exactly you looked into. Only one of the links you posted directly relates to food safety and crazing. The others relate to food safety and leaching of toxic materials and/or potter exposure to toxic materials. As I said before and I'll say again, crazing and leaching are two separate issues. You can have a glaze that crazes that doesn't leach significant amounts of toxic materials and a glaze that leaches that doesn't craze. Or you can have a glaze that does both or neither. The question that was asked and the question that I answered related to crazing. Both the issue of crazing and the issue of leaching / material toxicity are important, but it is not helpful to jumble up the two. deg |
#13
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Crazing
"plodder" wrote in message ups.com... Hi Xtra News, all very interesting. I think the items you unearthed tend to direct us towards sensible caution and precautions but for the sake of 'the public at large' those who sell their wares for use with food must be even more cautious. Enough said, I hope. Andy Yeah, probably. Been away apologies for not getting back sooner. I saw the Portage Ceramic awards in Auckland while away, only briefly we were running out of time. Its inspiring to see good work though. I am sure that I have seen it online for previous years. This one won't be online yet because it is still open but here is an article about it and one persons work. http://www.thebigidea.co.nz/article....&mode=&order=0 |
#14
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Crazing
"Dewitt" wrote in message ... On Fri, 25 Nov 2005 14:30:35 +1300, "Xtra News" wrote: Well I decided to do a bit more looking into this, Well, I'm not sure what exactly you looked into. Only one of the links you posted directly relates to food safety and crazing. The others relate to food safety and leaching of toxic materials and/or potter exposure to toxic materials. As I said before and I'll say again, crazing and leaching are two separate issues. You can have a glaze that crazes that doesn't leach significant amounts of toxic materials and a glaze that leaches that doesn't craze. Or you can have a glaze that does both or neither. The question that was asked and the question that I answered related to crazing. Both the issue of crazing and the issue of leaching / material toxicity are important, but it is not helpful to jumble up the two. deg Well it is a complex issue, but as mentioned before if you have underglaze decoration and a crazed glaze over I believe that it could be a hazard for food safety. I think it is an issue that we all need to keep vigilant about because it is important, both unsafe glazes, or crazed glazes, esp over underglaze decoration. |
#15
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Crazing
Lets bring up the barium and manganese dioxide issues for food safety
again... these sites here say that Manganese dioxide is poisonous on the macro gram level.... as in over a thousand grams!!!! Are you going to absorb hundreds of grams of Manganese dioxide from your glazed cup? Hundreds, tens? More than likely you would have trouble measuring the amount of manganese dioxide leached from a glaze. The same is true of barium. Its poisonous on the macro gram level. I hate this. Its irresponsible not to read the fricking articles about these substances and then start this hysterical nonsense about food safety again. Barium is not lead. Lead is very dangerous. It is poisonous on a microgram level and leaches substantially from a glaze. Lead should not be used in our studios. I would be more concerned about the effects of smoking tobacco in a studio than any of the chemicals that we use. The effects upon the potter of absorbing copper through our skin; the effects of dust and fiber from kaowool on our lungs... Food safety from crazing is really low on a list of what to worry about.... Russell Andavall Xtra News wrote: "Dewitt" wrote in message .. . On 22 Nov 2005 13:16:59 -0800, "plodder" wrote: I would like to pose some questions about the hygene aspect of crazing. Why does industry consider crazing a defect? Isn't any surface that is more difficult to thoroughly clean a minor health hazard? The primary reasons that industry considers crazing a defect are that a piece with a crazed glaze is substantially weaker than a piece with a glaze that "fits" properly and crazing is generally considered a visual defect. Personally, I doubt that crazing presents a significant hygiene issue and have never seen any research to indicate it does, but eating off crazed and stained dinnerware is certainly unappealing. deg Well I decided to do a bit more looking into this, I will not cut and paste anybody, perish the though ) been there, but I will post some sites, OK This one is fairly interesting http://ceramic-materials.com/cermat/education/271.html and this one by the same person http://ceramic-materials.com/cermat/education/144.html Run out of time, there were lots more sites. These two are not bad. It is something I feel strongly about that I think many potters do not seem as concerned as they should be IMO. Food safety with glazes is an issue. Talking of the past and how human kind survived is one thing, but we know that lots of people died of lead poisoning and today I trust that people are not using unsafe lead glazes. Take a look at these http://www.lenntech.com/Periodic-cha...ents/Cu-en.htm http://www.jtbaker.com/msds/englishhtml/m0715.htm These are just two glaze ingredients, one usually thought of as unsafe, the other as more safe, but you will see that we should take these things seriously. This is of course particularly important for us as potters, and I trust everyone wears masks and wet wipes to clean up etc etc. |
#16
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Crazing
On Tue, 29 Nov 2005 07:24:29 GMT, Russell Andavall
wrote: Lets bring up the barium and manganese dioxide issues for food safety again... these sites here say that Manganese dioxide is poisonous on the macro gram level.... as in over a thousand grams!!!! This primary concern with manganese is not leaching, but the exposure to manganese fumes by the potter during the firing process. Over time, exposure can result in Parkinson's disease like symptoms. For more info see http://ceramic-materials.com/cermat/education/155.html and http://www.ceramicstoday.com/articles/080999.htm And while the dangers of barium may not be as extreme as some believe, it is something that potters need to be aware of. Again, the danger is problem the greatest for potters who don't know how to handle it properly, though the leaching issue should not be dismissed. More info at: http://ceramic-materials.com/cermat/education/162.html deg |
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