|Monthly Tech-Tip |
The only way you will ever get the glaze you really need is to formulate your own. The longer you stay on the glaze recipe treadmill the more time you waste.
The traffic in glaze recipes has had a net negative effect on functional ceramics in education, hobby, and industry. Books and the internet are filled with recipes that are illogical and emphasize appearance at the expense of safety, practicality, or cost. 'Affairs' with these 'naked' (undocumented) recipes have left many numbed regarding their accountability and even ill equipped to recognize true quality. This trade in recipes fosters a culture that runs counter to the idea of 'understanding' and controlling our materials and recipes, it breeds ignorance of oxide and material sciences and the true nature of the ceramic process. It deludes many into an 'easy-fix' mentality that seeks 'foolproof' solutions that end up being blind allies that waste years and teach nothing. Implied 'ethics' suggest that the traffic in recipes be accompanied by documentation to prove givers conscientious and by critical analysis and testing on the part of recipients willing to 'understand' and adjust. Weak, leachable, difficult-to-clean, crazed, shivered, leaching glazes hurt the reputation of the pottery and ceramic industry. It is time that a 'want-to-know-why' mindset toward formulating and adjusting glazes on the oxide and material level is fostered in students. It is time that a stigma is attached to joining the 'illicit trade' in recipes and using trial-and-error bull-in-a-china-shop approaches to glaze formulation.
We recommend a 'base glaze with variations' starting model. As your understanding of a base glaze improves over a period of years you can develop the ability to identify its mechanism and learn to transplant them into different bases. In this way you can minimize the number of base recipes you use. In addition, as you improve each base (e.g. its application properties, fired harness, fit adjustability, etc) all the variations based on it will inherit the improvements.
In education and pottery circles the trade in recipes has encouraged a 'roulette wheel' approach to choosing glazes and in big industry there is a brain-drain toward suppliers and consultants while many manufacturers are becoming more and more helpless. At Digitalfire we personify these dangerous trends and attitudes as 'The Dragon'. The dragon wants you to believe that casual potters are exempt from technical concerns. He fosters blissful attitudes that keep us on an endless treadmill of glaze recipe experimentation and disappointment or on suppliers that lack a connection to unique circumstances and customer specific problems. The dragon wants us to think that glaze chemistry is too complicated and too much trouble.
Chemistry, that is, viewing your glazes as formulas of oxides rather than recipes of materials, is an invaluable tool to deal with things like hardness, strength, porosity, leaching, thermal shock resistance, chip resistance, glaze fit, color compatibility, of your functional ware. A typical formula contains eight or so oxides and it takes a lot less study to figure out what these contribute than it does to figure out what 100 different materials do. Glaze software, like Insight-live, provides the simplest way to work with glaze formulas.
Material prices are sky rocketing. And, the more complex your supplier's supply chain the more likely they won't be able to deliver. How can you adapt to coming disruption, even turn it into a benefit? Learn to create base recipes for your glazes and even clay bodies. Learn now how to substitute frits and other materials in glazes (get the chemistry of frits you use now so you are ready). Even better: Learn to see your glaze as an oxide formula. Then calculate formula-to-batch to use whatever materials you can get. Learn how to adjust glazes for thermal expansion, temperature, surface, color, etc. And your clay bodies? Develop an organized physical testing regimen now to accumulate data on their properties, learn to understand how each material in the recipe contributes to those properties. Armed with that data you will be able to adjust recipes to adapt to changing supplies.
G1214Z Cone 6 Matte Base Glaze
This glaze was developed using the 1214W glossy as a starting point. This article overviews the types of matte glazes and rationalizes the method used to make this one.
What is the Glaze Dragon?
At Digitalfire we use a Dragon to personify the kinds of thinking that prevent potters, educators and technicians from understanding and therefore controlling their ceramic glazes.
Ball Milling Glazes, Bodies, Engobes
Industries ball mill their glazes, engobes and even bodies as standard practice. Yet few potters even have a ball mill or know what one is.
Also called "middle temperature" by potters, cone 6 (~2200F/1200C) refers to the temperature at which most hobby and pottery stonewares and porcelains are fired.
G2926B - Cone 6 Whiteware/Porcelain Transparent Base Glaze
A base transparent glaze recipe created by Tony Hansen for Plainsman Clays, it fires high gloss and ultra clear with low melt mobility.