Food Safe and Stable Glazes




SKU: FS-0922
Start date

Product Description

Approx. €116 / 123 US$

What is the course about?

If you mix up your own glazes, whether just picking recipes from books and web sites or running your own R&D program, this course will help you by showing you what makes glazes leach, or not be food safe, or craze, and what you can do about it.

What are the Dates?

Select your start date from the list above.
The course is run over six weekly teaching sessions, plus a discussion at the end.
19:00 – 20:30 UK time / 20:00 – 21:30 CET / 2 p.m. – 3.30 p.m. EDT
Also recorded and put onto the course web page so you can view them at other times

If you can’t wait until the next run of the course, choose Recording instead of a start date. You get access to all the course material of the last run of the course, and 10 weeks in which to read and view the course material. You’re also free to contact me with any questions you may have during the course.

What will we cover?

The course begins with a quick recap of glaze chemistry and structure. It then looks at how glazes can be attacked in acidic (food) and alkaline (dishwasher) environments, and how you can make your glazes more stable. This includes using tools like Stull and limit formulae, as well as testing glazes in the studio and in the laboratory. 

We also look at the molecular structure of glazes, and how our glaze materials interact. This gives us a useful viw of the requirements for glaze stability based on the underlying chemistry, rather than the ad-hoc observations underlying other approaches.

To consider the food safety of glazes, we look at which components may be toxic and at what levels, and combine this with our work on glaze stability. We also look at food safety legislation (UK, EU and USA).

We also consider crazing, to determine in which circumstances it may or may not be acceptable, what causes it, and methods by which you can avoid it.

What will I achieve?

By the end of this course you should be able to:

  • Understand what is meant by glaze stability
  • Know how to use like the UMF, limit formulae, Stull chart and other guidelines to assess potential problems
  • Understand the mechanisms of glaze leaching in both alkaline (dishwasher) and acidic (food) environments
  • Understand which materials in glazes are potentially toxic, and how likely it is that a glaze will be toxic
  • Know how to test glazes in the studio, and sending glazes to a laboratory for testing
  • Take a glaze formula and improve its stability
  • Understand the causes of crazing
  • Take a glaze formula and increase or decrease its tendency to craze
  • Understand the legislation and standards covering food safety and testing (UK, EU and USA)

What level is the course and do I need any particular skills?

Intermediate to advanced. Some basic knowledge of glaze chemistry and glaze formulation is required.

How will I be taught, and will there be any work outside the class?

The course is primarily run through the weekly online sessions, which are a live lecture where you can also ask questions or get a discussion going. These are recorded and put on the course web page for those who cannot make the course times due to time zones or other commitments, or for those who want to replay them.

Additional material that you may wish to explore is on the course website. This will help you go deeper into the subject matter, should you wish to do so.

There will also be a discussion period at the end of the course, where we can discuss any of the course material or any more general questions you may have, including looking at any of your glaze recipes that you may wish to share.

There will be suggestions for you to test some of your pieces and glazes between sessions.

For those with an imperfect knowledge of English, all session recordings now have subtitles in the languages of all attendees. This uses computer translation, so isn’t guaranteed to be perfect, but should help you in following the sessions.

Are there any other costs? Is there anything I need to bring?

No advance preparation is needed.

You may want to test some of your work or test tiles (which will probably get damaged in the process).
This mostly uses standard studio and kitchen equipment, though the following are useful if available:

  • A pressure cooker
  • Methylene blue or a similar dark stain (5ml is plenty)
  • pH paper or a pH meter
  • 50g of soda ash
  • Vinegar or acetic acid
  • Lemon juice or citric acid

You may also want to have some glaze recipes that you can examine during the course.

What do I get?

  • Six live lectures with questions and discussions, lasting about 90 minutes each week
  • Recordings of all lectures for later viewing during the course, with subtitles in all attendees’ languages
  • Additional optional online course material, giving background info and greater depth
  • A discussion period, set up at a date/time for most students to attend even if not able to attend the live sessions
  • Downloadable PDFs of all presentations
  • Premium level access to the Tech part of my web site, containing much more information, references etc.
  • Course completion certificate

Note that the forum, lecture recordings and premium level site access are included at no cost until 4 weeks after the end of the course. After that, continued access is available for the cost of buying me a coffee every month (US$3 a month).

Feedback from students

The following feedback is from the previous version of the Product Safety course, of which this was a part:

I found the course both informative and enjoyable. Tim has a wealth of knowledge and experience, and a natural ability to present a technical subject in a way that makes it accessible to non-specialist. Recommended!
Edinburgh, UK 

I am happy to recommend Tim’s online webinar on Product Safety as a great way to improve the quality of your pots. He covers all the aspects of making from design to clay bodies, glaze materials and firing schedules. Coming from an engineering and design background his approach is quite different to that of the average art college. Whether or not you have a scientific background, testing and experimenting will become a natural part of your designing and making. Ideal for potters producing functional pots ranging from domestic ware to garden pots, who aim to improve their product.
St Albans, UK

Great couse, I’ve learned a lot thanks to Tim. His course is technical, complete and simple. I do recommend it.
Paris, France

Thank you Tim for your course. Good structure of each lesson, well prepared, I like the way you explain. You did a huge work. You give all your knowledge on the subject but without unusefull controversy. I recommend if someones want to have a large point of vue on product safety. Sorry for my approximative english.
Vannes, France

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