Jump to content
  • Announcements

    • Jennifer Harnetty

      Moderators needed!   12/08/2017

      Ceramic Arts Network is looking for two new forum moderators for the Clay and Glaze Chemistry and Equipment Use and Repair sections of the Ceramic Arts Network Community Forum. We are looking for somebody who is an active participant (i.e. somebody who participates on a daily basis, or near daily) on the forum. Moderators must be willing to monitor the forum on a daily basis to remove spam, make sure members are adhering to the Forum Terms of Use, and make sure posts are in the appropriate categories. In addition to moderating their primary sections, Moderators must work as a team with other moderators to monitor the areas of the forum that do not have dedicated moderators (Educational Approaches and Resources, Aesthetic Approaches and Philosophy, etc.). Moderators must have a solid understanding of the area of the forum they are going to moderate (i.e. the Clay and Glaze Chemistry moderator must be somebody who mixes, tests, and has a decent understanding of materials). Moderators must be diplomatic communicators, be receptive to others’ ideas, and be able to see things from multiple perspectives. This is a volunteer position that comes with an honorary annual ICAN Gold membership. If you are interested, please send an email outlining your experience and qualifications to jharnetty@ceramics.org.
Sign in to follow this  
Tyler Miller

Achaemenid Glaze And "the Origin Of Glazes" Essay

Recommended Posts

I just shut off the kiln for the night and I thought I'd share some of the reading I've been doing while the firing's been going on.  A while ago I posted a little something about Achaemenid glazes.  I've kept thinking about them since then, curious about figuring out a formulate for myself.  I found a very interesting essay here (http://www.gustav-weiss.de/files/GW_Essay-02_The-Origins-of-Glazes.pdf) on the origin of glazes.  I highly recommend giving the essay a read, it's very insightful about just how glazes came about.


"Chemical analyses (Hedges 1982) from the Achaemenid, Parthian and Sassanid periods (from 700 B.C. revealed glazes with the following boundary val- ues: 6-8 % Na2O, 2.5-4 % K2O, 4-8 % CaO, 2-4 % MgO, 2-3 Fe2O3, 4-8 % Al2O3 und 65-75 % SiO2. After a phase diagram by Morey (1930), this ratio of alkali to earth alkalis and silicic acid needs a firing range of 900°-1100°C. These glazes were ap- plied to a body with 16-17 % CaO, 5-6 % MgO und 50 % SiO2, which corresponds to the lime-rich clays of the Middle East."




10% soda ash, 10% potash feldspar, 10% dolomite, 10% kaolin, and 60% silica puts you right in the ball park of that chemistry.  Historically, this would likely have been soda/natron and local sand, just like Egyptian glass. 


Edit:  It occurred to me that I should share how I arrived at that recipe.  The essay talks about plant ash and sand as the origin of this type of glaze, but I'm not sure how realistic this is when trying to replicate the result.  I tried every known plant ash, and I couldn't make it work.  There are plants in the mediterranean and elsewhere that take up soda and potash in tremendous quantities, e.g saltwort (salsola soda), but I don't have those, and it was later found in ancient glass making that substances like natron form a better glass than ash.  In fact, it wasn't until the breakdown of trade routes that ash became important in glassmaking again.  



Thought I'd share :)

mel340 likes this

Share this post

Link to post
Share on other sites

WOW! Thanks for the reference Tyler. I got interested and went to Weiss's main page http://www.gustav-weiss.de  This guy is amazing! I also love the great display of his glaze painting and sculptor.


Spent about three hours reading his essays and looking at his art. This guy is a true ceramic philosopher not to mention a fine ceramic artist.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  


Important Information

By using this site, you agree to our Terms of Use.