lakesidepottery Posted January 1, 2011 Report Share Posted January 1, 2011 Can matt glazes be used for food ware? We have received several questions regarding the use of matt glazes for functional ware and have found that the answer is not that straight forward. The following is our recommendation: What is Matt Glaze? One or all of the symptoms below may occur with matt glazes. What is acceptable to you is an individual decision. Testing to discover which of the three will be presented in your matt glaze is advisable. 1) Food Staining (e.g., coffee, tomato sauce or other acidic foods) 2) Food particles might not wash off thoroughly because of the porous/ unsmooth surface and can result in bacteria growth 3) Matt glazes may be more likely to leach hazardous glaze materials into the food while a glossy surface acts as a tight seal Testing items 1 and 2 above is not difficult and will determine if your matt glaze stains or holds food particles. The difficult issue is item number 3 (hazardous materials leaching into food). We have done our own research and spoken with Jeff Zamek who wrote the book, Safety in the Ceramics Studio, and have concluded that for legal reasons, not actual problems with the glaze, it is best to not claim matt glazes to be food safe. There have been no reported cases of people eating or drinking from matt glazes having a poisoning problem. It’s just not an issue on that level with over 60 years of matt glaze being used by potters. Also, Zamek’s research found that the National Health records did not indicate health issues from matt glazes. However, especially in the past few years, people have become very litigious and even if the potter can prove no cause-and-effect, it takes time and money to defend. Given the above, we, at Lakeside Pottery, have decided it is better to be on the conservative side. We instruct our students and studio users to not use matt glazes for food ware. We do show our students that with some shapes, pitchers for example, a glossy glaze can be applied to the inside while the outside can be matt. Note: We have found that some glazes are impacted by acidic foods (e.g., lemon, vinegar) where the glaze color changes. One of our glazes that change color with acidic foods is Water Color Green Conclusion: Don’t take anybody’s word on the safety of a particular recipe. Even if it was safe at one point, small change in materials, firing, and clay could result in an unstable glaze. It can be harder to recognize an unstable matte glaze because a heavily leaching surface will not evidence itself with loss of gloss as it would in a glossy glaze. The only way to be sure is to have them lab tested. See our matt glazes recipes Link to comment Share on other sites More sharing options...
Pat Franz35 Posted January 13, 2011 Report Share Posted January 13, 2011 We all like the bold bright look of some Matte Glazes While others like the drab look. I would suggest that you look into the Duncan Satin Glazes. They are food-safe. They called them Matte Glazes back in the 70's and 80's. A commercial glaze yes, but at $4.00 or so a jar you can try all you want. Also, check into the Courtyard Glazes. They are all non-toxic. Pat Franz www.BercherCeramicSupply.com 405-634-6922 Link to comment Share on other sites More sharing options...
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