Retxy Posted June 17, 2022 Report Share Posted June 17, 2022 Hello people much smarter than me! I recently read mc6 and my mind has been blown. So much I don't understand. However I am barreling forward regardless! My question is: when a large company labels a glaze food safe are they only required to use the leaching values for lead and cadmium? I understand the rules for toxic vs nontoxic, but not if these companies are using limit formulas for other items besides cadmium and lead. If there are other standards they are held to, where could one find these published limits? Mc6 states that one can make their own guidelines but I am not educated enough and a point of reference would help me greatly. Thanks!!! D Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted June 17, 2022 Report Share Posted June 17, 2022 (edited) Just my observation - You had me thinking what mc6 was then I realized likely mastering cone 6. Without getting too much in the weeds, lead and cadmium in the US, in pottery are regulated. Other substances, not necessarily so. To complicate matters, leaching is an obvious issue, but should durability be one also? How do we define durability? Anyway, maybe start here: https://www.maycocolors.com/resources/dinnerware-food-safety/ for a perspective from Mayco. Because of the leaching potential, most potters tend to err on the side of caution when mixing their glazes or choosing a liner. That often means I don’t use lead, cadmium, even barium and vanadium for instance for food wares. I don’t even keep them in my chemical stores for glazes. Because of the differences in just the definition of durability many will test, maybe lemon, maybe dishwasher, maybe make a judgement of the formula based on limits. Again, in general through experience they are trying to be as reasonably safe as practical while knowing that true testing for all possible degradation is very difficult at best. So for an experienced conscientious potter, their level of caution is likely reasonable especially if they test and have observed their glazes in use over a significant period of time. I think this is likely the intention of establishing your own guidelines. As you may have noticed, various limits overlap so they are actually guidelines, not necessarily a precise limit. The good news, there are folks familiar enough to observe that something likely needs more silica to be more durable. Probably not a bad observation, but truly testing is the final more definitive answer. The better news, done within reason and reasonable caution, ceramics are relatively sturdy in comparison to generations of humans. In other words comparatively durable and lasting. Edited June 17, 2022 by Bill Kielb Rae Reich 1 Quote Link to comment Share on other sites More sharing options...
Retxy Posted June 17, 2022 Author Report Share Posted June 17, 2022 Bill, Thank you so much for your wonderful reply!!! You correctly deduced that I was referring to masteringncone 6. Thank you so much for that article as it clears up a lot of things for me. I agree that there are certain things that I also will not stop in my glaze chemicals, but was wondering if there were published standards somewhere as far as the leaching of other chemicals and if this was regulated. For example I did not know that over 5 mg per liter of copper bleaching gave food a metallic and bitter taste until I read mc6!!! And though the authors give some ranges I had wanted to know if there was some regulation that someone knew of from the FDA or others but now that I see that even Mako is only really concerned about lead and cadmium and I have learned enough on what to avoid ( batiumd, vamnadium lithium etc), I feel more confident!!! Thanks so much!!! Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted June 17, 2022 Report Share Posted June 17, 2022 (edited) 4 hours ago, Retxy said: I had wanted to know if there was some regulation that someone knew of from the FDA I am not aware of any “ceramic limits” other than limits established for consumption likely “FDA” or other testing body limits of consumption. I have seen others attempt to quantify this in ceramics but it is complicated with respect to how much one could physically ingest. their weight, the composition of the solvent (food / liquid), near infinite variations in glaze chemistry and so on. Just as an example to use the copper citation above, how do we measure the 5 parts per million of copper? Much is dependent on the amount of leaching from the amount of available surface in contact with the solvent and then how much was consumed. Turns out very difficult to determine and likely more so for other ingestion limits. Edited June 17, 2022 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
Min Posted June 17, 2022 Report Share Posted June 17, 2022 14 hours ago, Retxy said: My question is: when a large company labels a glaze food safe are they only required to use the leaching values for lead and cadmium? I understand the rules for toxic vs nontoxic, but not if these companies are using limit formulas for other items besides cadmium and lead. In the US at this point in time yes. I believe new regs are coming to some countries in Europe. 11 hours ago, Retxy said: ...I had wanted to know if there was some regulation that someone knew of from the FDA or others... You can look at drinking water limits and compare them to ceramic glaze leaching figures from a lab such as BSC Labs which uses glacial acetic acid to drinking water to test for leaching. 11 hours ago, Retxy said: I have learned enough on what to avoid ( batiumd, vamnadium lithium etc) Lets not throw the baby out with the bath water. Practicing good studio hygiene and using transition metals (colouring oxides) in reasonable amounts and the least possible amount to get the desired colour and making a durable base glaze fired to maturity will negate most concerns. Anybody that uses bright reds, oranges, and even some of the yellow and green underglazes or glazes is using stains that more than likely contain cadmium (Cd) in the form of an inclusion stain. Far and away safer and less leachable source of Cd than than using cadmium oxide. Many bright aqua, green and yellow stains contain vanadium. Again, in a stain form far and away safer for both the potter during making the pots and the consumer because the stains are far less likely to to be bioavailable than using the raw oxides. Lithium is found not only in lithium carbonate but also in spodumene, petalite, a few frits and lepidolite, it is not an issue as far as toxicity is concerned when used with appropriate studio hygiene and reasonable levels. Barium is one of the oxides that most people who fire to cone 6 avoid in North America. Looking at the bioavailability of materials is important. Is the material bioavailable in the metallic form, oxide form, salt form or fumes? A material may be toxic in one form and not another. Manganese dioxide / oxide is an example of this. Manganese dioxide / oxide is not soluble in water therefore cannot be absorbed through the skin or even an open cut, and even if ingested cannot dissolve into the blood stream. Manganese fumes from the kiln firing however are bioavailable and harmful. (Manganese salts, chloride, nitrate, or sulfate, are very harmful but as these aren't commonly used by studio potters not likely an issue for this thread.) Having a base glaze with as much alumina and silica as the glaze can melt into the glassy matrix is really important to a glazes durability. If a glaze is low on either of these the greater the chances of it not being durable. Insofar as utilitarian ware a durable glaze needs to withstand both acid and alkaline attack, be non staining and resist cutlery marking. Doing a lemon/vinegar test will rule out glazes attacked by acids, keeping a sample of glaze in the dishwasher for many months will rule out ones prone to alkaline attack. "Limit" Formulas aka "Target" Formulas can be helpful to look at but there are many many glazes that fall outside the "Limits". What could be the most help to you is to look at the silica and alumina levels for a durable glaze. Try to avoid glazes at or below the lower levels of alumina and silica in "Limit" Formulas. If you put a recipe in Glazy you can see the amounts of each oxide present in the glaze, take these figures and compare them to "Limit" charts. These Limit or Target charts have gone out of favour with some potters but I think they can be a useful tool to have in the toolbox along with others. A lot of the highly visually textured glazes will be overloaded with one or more of either boron or one of the fluxes. Boron is necessary for all but Bristol type glazes to get a good melt at cone 6. Oversupplying boron can result in some really beautiful glazes but by oversupplying boron the resulting glaze will be soft and less durable. Getting to know what qualities each oxide adds to the glaze is really helpful. Welcome to the forum Hulk 1 Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted June 18, 2022 Report Share Posted June 18, 2022 (edited) Just to add to the above, there are efforts to unify (Globally) various chemical compositions which in theory can lead to more uniformed application, classification and restriction globally. If you have not done so already, Mayco continues to explain some of this reasonably clearly as well as cite some US agencies in place to establish and protect people in general. You may find it a good read https://www.maycocolors.com/resources/health-safety/ An additional fairly recent study on durability and chemistry correlation you may find interesting as well here: https://www.ceramicmaterialsworkshop.com/uploads/5/9/1/2/59124729/katz_matthew_glossed.over.durable.glazes-2018.pdf It does highlight the “acid test” may not really be the best indicator of degradation in all cases. Glaze durability is complicated, actual exposure to various substances especially by consumption is probably even more complex. Edited June 18, 2022 by Bill Kielb Hulk 1 Quote Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted June 18, 2022 Report Share Posted June 18, 2022 The lemon test should be a minimum standard. It won’t reveal all weaknesses, but if a glaze fails the lemon test, it’s not going to be a good choice for a coffee mug liner. Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted June 19, 2022 Report Share Posted June 19, 2022 (edited) 2 hours ago, Callie Beller Diesel said: The lemon test should be a minimum standard. It won’t reveal all weaknesses, but if a glaze fails the lemon test, it’s not going to be a good choice for a coffee mug liner. Definitely agree, but the Katz research (pictured below) makes a good point re: the danger of passing that test: interesting research, interesting read, interesting presentation at NCECA 2016 interesting observations on gloss as well.. Full paper here for more clarity https://www.ceramicmaterialsworkshop.com/uploads/5/9/1/2/59124729/katz_matthew_glossed.over.durable.glazes-2018.pdf Edited June 19, 2022 by Bill Kielb kswan 1 Quote Link to comment Share on other sites More sharing options...
Retxy Posted June 19, 2022 Author Report Share Posted June 19, 2022 On 6/17/2022 at 11:52 AM, Min said: In the US at this point in time yes. I believe new regs are coming to some countries in Europe. You can look at drinking water limits and compare them to ceramic glaze leaching figures from a lab such as BSC Labs which uses glacial acetic acid to drinking water to test for leaching. Lets not throw the baby out with the bath water. Practicing good studio hygiene and using transition metals (colouring oxides) in reasonable amounts and the least possible amount to get the desired colour and making a durable base glaze fired to maturity will negate most concerns. Anybody that uses bright reds, oranges, and even some of the yellow and green underglazes or glazes is using stains that more than likely contain cadmium (Cd) in the form of an inclusion stain. Far and away safer and less leachable source of Cd than than using cadmium oxide. Many bright aqua, green and yellow stains contain vanadium. Again, in a stain form far and away safer for both the potter during making the pots and the consumer because the stains are far less likely to to be bioavailable than using the raw oxides. Lithium is found not only in lithium carbonate but also in spodumene, petalite, a few frits and lepidolite, it is not an issue as far as toxicity is concerned when used with appropriate studio hygiene and reasonable levels. Barium is one of the oxides that most people who fire to cone 6 avoid in North America. Looking at the bioavailability of materials is important. Is the material bioavailable in the metallic form, oxide form, salt form or fumes? A material may be toxic in one form and not another. Manganese dioxide / oxide is an example of this. Manganese dioxide / oxide is not soluble in water therefore cannot be absorbed through the skin or even an open cut, and even if ingested cannot dissolve into the blood stream. Manganese fumes from the kiln firing however are bioavailable and harmful. (Manganese salts, chloride, nitrate, or sulfate, are very harmful but as these aren't commonly used by studio potters not likely an issue for this thread.) Having a base glaze with as much alumina and silica as the glaze can melt into the glassy matrix is really important to a glazes durability. If a glaze is low on either of these the greater the chances of it not being durable. Insofar as utilitarian ware a durable glaze needs to withstand both acid and alkaline attack, be non staining and resist cutlery marking. Doing a lemon/vinegar test will rule out glazes attacked by acids, keeping a sample of glaze in the dishwasher for many months will rule out ones prone to alkaline attack. "Limit" Formulas aka "Target" Formulas can be helpful to look at but there are many many glazes that fall outside the "Limits". What could be the most help to you is to look at the silica and alumina levels for a durable glaze. Try to avoid glazes at or below the lower levels of alumina and silica in "Limit" Formulas. If you put a recipe in Glazy you can see the amounts of each oxide present in the glaze, take these figures and compare them to "Limit" charts. These Limit or Target charts have gone out of favour with some potters but I think they can be a useful tool to have in the toolbox along with others. A lot of the highly visually textured glazes will be overloaded with one or more of either boron or one of the fluxes. Boron is necessary for all but Bristol type glazes to get a good melt at cone 6. Oversupplying boron can result in some really beautiful glazes but by oversupplying boron the resulting glaze will be soft and less durable. Getting to know what qualities each oxide adds to the glaze is really helpful. Welcome to the forum Thank you SO much for this insightful reply!! Is getting to know each oxide just a matter of reading through the digital fire profiles on each or is there a resource that you have found helpful? I did not know that about manganese and honestly would not know where to pick up little tidbits like that. I am struggling just now to learn how to do substitutions and not understanding what I am working with, so any resource you have found helpful I would welcome. I have MC6 and have found it useful, but aside from giving limits, there was not enough room for discussion of each of the recommended materials. Thanks so much!! Quote Link to comment Share on other sites More sharing options...
Retxy Posted June 19, 2022 Author Report Share Posted June 19, 2022 18 minutes ago, Bill Kielb said: Definitely agree, but the Katz research (pictured below) makes a good point re: the danger of passing that test: interesting research, interesting read, interesting presentation at NCECA 2016 interesting observations on gloss as well.. Full paper here for more clarity https://www.ceramicmaterialsworkshop.com/uploads/5/9/1/2/59124729/katz_matthew_glossed.over.durable.glazes-2018.pdf Thank you so much for this! I'm scare now, but better to know now instead of later. Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted June 19, 2022 Report Share Posted June 19, 2022 1 minute ago, Retxy said: Thank you so much for this! I'm scare now, but better to know now instead of later. If you read through his paper his research says glazes within a reasonable flux range are likely to be durable, those outside an acceptable range are likely not, so a bit more reassuring. Test, observation very important as well as using oxides and colorants sensibly. Quote Link to comment Share on other sites More sharing options...
Retxy Posted June 19, 2022 Author Report Share Posted June 19, 2022 Bill the r20:r0 ratio is a new concept for me. I have hyperglaze and am struggling to learn it. I don't see this as an offered ratio is this just something I get to calculate by hand? Thank you for your rapid replies and kind help!! I am so grateful Quote Link to comment Share on other sites More sharing options...
Retxy Posted June 19, 2022 Author Report Share Posted June 19, 2022 11 minutes ago, Bill Kielb said: If you read through his paper his research says glazes within a reasonable flux range are likely to be durable, those outside an acceptable range are likely not, so a bit more reassuring. Test, observation very important as well as using oxides and colorants sensibly. Bill the r20:r0 ratio is a new concept for me. I have hyperglaze and am struggling to learn it. I don't see this as an offered ratio is this just something I get to calculate by hand? Thank you for your rapid replies and kind help!! I am so grateful Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted June 19, 2022 Report Share Posted June 19, 2022 (edited) 28 minutes ago, Retxy said: Bill the r20:r0 ratio is a new concept for me. I have hyperglaze and am struggling to learn it. I don't see this as an offered ratio is this just something I get to calculate by hand? You can learn UMF and Katz did have a free spreadsheet on his website that will calculate all this for you or if you enter your glaze on Glazy.org (free) the UMF will be generated for you. Most glaze software apps report R2O:RO (Flux ratio) for you. The essence of the research says a flux ratio of 0.3:-0.7 is likely the most durable. In generał I prefer to try and limit my flux range 0.2:0.8 to 0.3:0.7 for glazes I consider as liners. Higher than 0.3:0.7 seems to fall off in durability quickly. Anyway, I would recommend The Katz course on glazes from a material science approach, he does a fair job IMO. Here is a Glaze below (on Glazy) Marcia and I (under Madison pottery) created it to be a Matte, but notice the flux ratio intentionally is in that magic range for us - 0.23: 0.77. The glaze software displays the value. BTW, still have a test piece in the dishwasher for probably over two years. Edited June 19, 2022 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
Retxy Posted June 19, 2022 Author Report Share Posted June 19, 2022 28 minutes ago, Bill Kielb said: You can learn UMF and Katz did have a free spreadsheet on his website that will calculate all this for you or if you enter your glaze on Glazy.org (free) the UMF will be generated for you. Most glaze software apps report R2O:RO (Flux ratio) for you. The essence of the research says a flux ratio of 0.3:-0.7 is likely the most durable. In generał I prefer to try and limit my flux range 0.2:0.8 to 0.3:0.7 for glazes I consider as liners. Higher than 0.3:0.7 seems to fall off in durability quickly. Anyway, I would recommend The Katz course on glazes from a material science approach, he does a fair job IMO. Here is a Glaze below (on Glazy) Marcia and I (under Madison pottery) created it to be a Matte, but notice the flux ratio intentionally is in that magic range for us - 0.23: 0.77. The glaze software displays the value. BTW, still have a test piece in the dishwasher for probably over two years. Am i missing this in hyperglaze? i have attached a selsor chun recipe that I am working on but i keep getting a message that potassium and sodium are undersuppplied but the ratio of these two is in a good range. so frustrating. but i don't see the r20:r0 ratios. I can switch to glazy or the katz website, but I went with hyperglaze bc mc6 recommended it. Is it there im simply not seeing it? Thanks! Quote Link to comment Share on other sites More sharing options...
Retxy Posted June 19, 2022 Author Report Share Posted June 19, 2022 a little background, the original recipe had FFF feldspar, but I'm trying to sub mahavir and failing miserably. original recipe: https://glazy.org/recipes/9792 Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted June 19, 2022 Report Share Posted June 19, 2022 (edited) 43 minutes ago, Retxy said: Am i missing this in hyperglaze? i have attached a selsor chun recipe that I am working on but i keep getting a message that potassium and sodium are undersuppplied but the ratio of these two is in a good range. so frustrating. but i don't see the r20:r0 ratios. Yes, I don’t see it displayed but have never used hyperglaze. UMF originates from Hermann Seger I believe who was seeking a way to relate chemistry, composition and performance. Wiki link here https://second.wiki/wiki/hermann_august_seger. Anyway since the 1800’s it’s proven a useful way to understand glaze chemistry. For your recipe and materials substitution I believe digital fire makes substituting easy. For me I often just look up the materials, pick the next closest available and hand adjust as a quick way. While Glazy is not built directly for this Derek Au does do a few substitutions on video. One such similar posted by Sue McCloud https://youtu.be/z7k_X_1i-s0 does a reasonable job of explaining the process Using Glazy. I really think the digital fire software allows one to substitute more easily though, but I do not use it so do not have direct knowledge. I don’t want to speculate about limit warnings. if you reviewed the limit table, there is an amazing amount of overlap in the allowable so from cone to cone, table to table and there is no real way to correlate the effect of multiple limit violations. Just me though, some folks find them useful. Drop your recipe in Glazy, it will display the UMF and extended UMF Edited June 19, 2022 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
Retxy Posted June 19, 2022 Author Report Share Posted June 19, 2022 3 minutes ago, Bill Kielb said: Yes, I don’t see it displayed but have never used hyperglaze. UMF originates from Hermann Seger I believe who was seeking a way to relate chemistry, composition and performance. Wiki link here https://second.wiki/wiki/hermann_august_seger. Anyway since the 1800’s it’s proven a useful way to understand glaze chemistry. For your recipe and materials substitution I believe digital fire makes substituting easy. For me I often just look up the materials, pick the next closest available and hand adjust as a quick way. While Glazy is not built directly for this Derek Au does do a few substitutions on video. One such similar posted by Sue McCloud https://youtu.be/z7k_X_1i-s0 does a reasonable job of explaining the process Using Glazy. I really think the digital fire software allows one to substitute more easily though, but I do not use it so do not have direct knowledge. I don’t want to speculate about limit warnings. if you reviewed the limit table, there is an amazing amount of overlap in the allowable so from cone to cone, table to table and there is no real way to correlate the effect of multiple limit violations. Just me though, some folks find them useful. Drop your recipe in Glazy, it will display the UMF and extended UMF Bill, If no one has ever told you that you are amazing, please know that you are. I can't thank you enough for your help with all of this!!! I have been playing around withthe katz spreadsheet just now, and the numbers i'm getting are vastly different from what hyperglaze is saying. So much fun. I can't wait to watch the videos you posted. Thank you!! Bill Kielb 1 Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted June 19, 2022 Report Share Posted June 19, 2022 13 minutes ago, Retxy said: If no one has ever told you that you are amazing, please know that you are. I can't thank you enough for your help with all of this!!! While I appreciate the compliment greatly, understand folks have studied glazes for many years and no one has conquered all aspects. New ways, old ways, many have some validity under the near infinite number of recipes.. If you go on to study glazes you very well could discover the next best tidbit in glaze science. There are a lot of very generous folks here with great experience. All points have some validity so my suggestion, gather each, discriminate appropriately and develop your own experience………… oh yeah, and please share what you find in the future. Quote Link to comment Share on other sites More sharing options...
Min Posted June 19, 2022 Report Share Posted June 19, 2022 3 hours ago, Retxy said: I am struggling just now to learn how to do substitutions and not understanding what I am working with, so any resource you have found helpful I would welcome. There are only a dozen or so main oxides that are used for ceramic glazes (not including transition metals aka colouring oxides, and opacifiers). Many of the materials we use are made up of multiple oxides. For example all glazes (and claybodies) are going to contain alumina. Alumina in glazes is most commonly found in either a kaolin or a ball clay. So if a glaze needs alumina the go to is to add kaolin or ball clay. If you take a quick look at either of these materials you will see they contain alumina but also silica + some fluxes and a tiny bit of iron. Therefore by adding kaolin or ball clay you are also adding the other oxides. What you want to aim for is supplying the oxides with materials that suit the purpose the best. For example frits containing boron and Gerstley Borate (or Gerstley Borate substitutes) are what supply boron. (key for most cone 6 glazes) Many people prefer to supply boron with a frit as opposed to Gerstley Borate as frits don't have some of the negative issues Gerstley Borate has like gelling a glaze. It takes time to learn what materials contribute what but a brief chart here will get you started. There is a wealth of info on the Digitalfire website. Yeah, there is something wonky with your Hyperglaze flux data. I don't use it so can't help correct what's going on there. I don't want to do your "homework" for you but just for reference sake I put the original Selsor Chun that you linked from Glazy into Insight. I then did a 1:1 swap of the FFF Feldspar for Mahavir (second recipe). Honestly this is probably close enough to just test as is. The sodium and potassium amounts are different as FFF spar has a fair bit less potassium and more sodium than Mahavir. Could be a slight shift in colour between the FFF spar and Mahavir. To balance the sodium and potassium I added some sodium in the form of Ferro Frit 3110 (high sodium frit) then rebalanced everything and re-totalled to 100. Its common studio practice to have the base glaze equal 100. Makes it easier to compare glaze recipes and add colourants etc. Hulk 1 Quote Link to comment Share on other sites More sharing options...
Min Posted June 19, 2022 Report Share Posted June 19, 2022 12 hours ago, Retxy said: I'm scare now, but better to know now instead of later. People can make things more scary than they need to be. Common sense when it comes to ceramics will go a long way. It's good you are interested in learning about glaze chem but please don't feel overwhelmed by it. If you use a well melted gloss glaze for liners that doesn't contain any transition metals / colouring oxides there won't be anything harmful to leach out. For sure there is a lot of information to take in. The lemon slice test (or household white vinegar) test mimics the ASTM test that uses 4% acetic acid to test for cadmium and lead where the leachate is tested. It won't rule a glaze as being 100% non leaching but it will rule out glazes that are visibly degrading as not being suitable for use on pots coming in contact with food surfaces. Same as the dishwasher alkaline test, it is meant to rule glazes out as being durable, not definitively rule them in. In the images above from Katz's paper on durable glazes it looks like copper was used in the base glazes. Copper is probably the most difficult colouring oxides to keep from leaching out of a glaze so keep that in mind. One other point from that same paper was a test with a flux ratio of 0.1 R2O : 0.9 RO being "surprisingly robust". There are many factors to be taken into consideration! "Yet in this series 0.1 R2O:0.9 RO was surprisingly robust. The glazes themselves have an average baseline gloss of 68.8, higher even than 0.3 R2O:0.7 RO. The degradation levels showed adequate performance, with an average of 2.8%. This value may be misleading since a boron level of 0.5 had only 1.62% degradation, while the 0.4 boron level was a still low at 3.98%. But the curve and slope of this series matches 0.3 R2O:0.7 RO almost perfectly. This result will be explored in future research, along with the effects of altering the silica /alumina ratio and the role of colorants such as copper." Hulk and ATauer 2 Quote Link to comment Share on other sites More sharing options...
ATauer Posted June 28, 2022 Report Share Posted June 28, 2022 MC6 is an excellent book but skips quite a bit of information. I think you would find some of the things you are missing by reading John Britt’s Midrange guide, and Robin Hopper’s book is fantastic, even if it is a bit out of date and still has some stuff in it that we absolutely wouldn’t do today. It will especially help your color development. I enjoy Linda Bloomfield’s books, especially her Special Effects Glazes, although her books besides that one can be more heavily on recipes but do have background information you need first. I’m forgetting the author, but the New Ceramics series book Developing Glazes really helped me learn more about testing glazes, doing biaxials, triaxials, quadraxials and introduced me a little to Ian Currie’s methods. The only thing I found frustrating about the book was its constant inclusion of lead in lowfire glazes despite being written around 2013 when all other glaze books of the period had firmly left lead behind. If you really want to dig deep, read Ian Currie’s book…but I think that may be something you might want to keep until you have more of handle on things. Spend time on Glazy- when you have an account a feed will just show up that you can narrow down to recipes or to blog posts (I recommend doing both, the blog posts are fascinating and I have learned a ton about glaze chemistry from them. Also by spending time looking at recipes you are interested in, or just the feed, you will see a rich comment conversation for many of them that often have multiple people problem solving or answering someone’s question that you didn’t know. It seems overwhelming but I managed to teach myself glaze chemistry well enough to be ready to start teaching introductory workshops on it within just a few months- and that wasn’t me deciding I was ready, a mutual glaze nerd was the one who told me I was far and away ready to start teaching basic glaze classes, and maybe even some specialty ones like using silicon carbide in oxidation or changing cone 10 glazes to cone 6. I was completely shocked when she told me that as I felt I had so so much more to learn (and I do) but once you dive into it the information comes fast and steady and you can pretty quickly pick up a lot of information. * Do make sure you research your colorants, know their toxicities and routes of exposure, read MSDS sheets on them, and then after that…don’t freak out. Most you really aren’t going to get enough exposure to or be handing in such a way as it has a route into your body*. Check out the episode of the podcast For Flux Sake with the toxicologist, it is really good. I did it by checking out every single glaze book from the library and reading all of them, even the ones I wanted to throw on a fire for having very incorrect information. I spent (and spend) a huge amount of time on Digitalfire, it is like Wikipedia, you look up one thing or just go read the lasted blog and get sucked down a rabbit hole of page after page and learn a ton of information. And Tony Hansen is a real sweetheart, if you are confused by something on his website just fill out the contact form and he will email you very promptly and thoroughly answer any questions you have. I found that out because I was frustrated that the information on pyrophyllite and mullite said that you could substitute a certain amount for the silica or some of the feldspar, but there were not even vague guidelines, and I had a hell of a time finding guidelines elsewhere (eventually found that you can substitute basically as much of either of those for the silica, not the feldspar, as much as you want, including completely replacing it, but it is more common to do about 50:50.). Tony immediately went to work using Insight to test various potential recipes with how much pyrophyllite or mullite you put in, and what effect it has, so he’s actually putting in a lot of work to come up with good guidelines. Ceramic Materials Workshop is hands down probably one of the easiest and fastest ways to learn a lot of what you want to know, not that it is a complete education. I felt I had learned enough on my own that I didn’t need their big intro course Understanding Glazes, so I chose their on demand Cone 6 Workshop which when you compare the lectures between the courses they are extremely close, with Cone 6 being a little shorter. You can sign up for the Intro course for lectures only or several times a year (like this July!) they do it with a full experience, labs, pre-lecture readings, meetings every two weeks with the Katzs for questions and chatting. I’ve never heard anyone say they regretted they took it, or really much of a bad word about it. I signed up for their clay class lectures only because I needed the information right exactly then, but they allowed me to upgrade for this July so I’ll be able to do the full class with labs and so forth, and while I managed to develop a pretty great porcelain recipe from just the lectures, I’m planning on developing a white stoneware and maybe also a porcellanous stoneware, although I’ll probably just mix my whit stoneware and porcelain together to make it a lot easier! If you don’t want to do that, I do believe if you sign up for a pretty low amount per month of the CMW’s Patreon there is a zoom open chat with Matt Katz towards the beginning of each month where you can ask tons of questions. It’s an affordable way to get face time and actually get your questions answered, unlike the lottery that is For Flux Sake. I’m planning on doing it after I have finished my clay class since I will have face time there. But I will probably only sign up for a few months at a time, when I have burning glaze questions. You don’t have to do it the full year. I have only actually so far done about 30% of my CMW cone 6 workshop, but that is because I skipped around instead of going in order to get the lectures I really needed answers from at the time, which was fantastic, and now I’m starting from the beginning and trying to mostly go through it in order, with plans to rewatch some of the ones I watched first. It is not the only way to learn by far, I definitely learn stuff from the CMW courses but a lot of it I already know through lots and lots of reading. It really is the cornerstone of learning glaze chemistry. There are some great resources on YouTube, John Britt does a fantastic free glaze course that he continues to add videos to and he is great at explaining things, and loves demos. And he will go over a lot of the real basic stuff, he does not skip that, so that might be just what you are looking for, as just like his books he really covers things but he gets to expand on his books a ton with his series. I highly recommend checking him out. For glaze software, honestly if you can get a refund on HyperGlaze try to, just using Glazy and opening up some extra features by becoming a patron (preferably through paypal- I just paid my whole year at once for $20 and I know it is going to an incredible nonprofit and that Derek Au is not making any money of it, quite the opposite actually). Glazy usually has enough of what I need, but the best glaze software is definitely Insight from Digitalfire and it is extremely reasonable, plus they have a free desktop version. You would have a lot less head butting with either of those options, you just need to know with Glazy that you want to be a supporter so you have access to Target & Solve, and a couple other great features. You can also put in the cost of your materials and calculate how much a batch of glaze is going to cost you. Sorry for the long post, I just had major surgery and can’t fall asleep, and it seemed silly to break up each topic into its own reply to you. I hope some of this helps. It seems really frustrating now but you will be totally shocked at what you will know in a few months. You’ll be a rockstar, especially with such an enquiring mind. Min and Hulk 2 Quote Link to comment Share on other sites More sharing options...
Min Posted June 28, 2022 Report Share Posted June 28, 2022 Another good resource for learning about glaze chemistry and what some of the verbiage means is from Phil Berneburg's videos from The Potters Round Table. Link here to an intro to glaze chem part 1 of 2. @ATauer, best of luck with your recovery. Quote Link to comment Share on other sites More sharing options...
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