Friday, August 3, 2012

Low Fire Friday - A brief into to glazes and glaze mixing


Glaze – A Brief Intro

A glaze is glassy substance that has been adhered to the surface of ceramics through firing. It is made up of a glass former, a stabilizer and a flux

 The glass former is the glass. Typically this will be in the form of silica/flint

The stabilizer is what keeps the glass from completely running off of the ceramic piece.
Alumina is the main stabilizer and is found in clay.

The flux is an oxide (generally Alkaline) which causes ceramic fusion when combined with other oxides and heated.

Glaze recipes are usually written as a list with ingredients totaling 100%. This base glaze is usually clear/white. Any colorants, opacifiers, suspenders, and gums are written below the 100% line and are added as a percentage of the total glaze.

Base 4 
Base Glaze
Frit 3195
65

Gerstly Borate
10

Wollastonite
15

EPK
10


100




Bentonite
2



Colorants


Dark Brown
Red Iron Oxide
10

Glazes are usually measured and mixed by weight. However, any unit of weight can be used as long as it is constant throughout the entire recipe. I weigh my materials out in grams and typically mix a 500g batch (about the size of a large yogurt container). This means that I would multiply each material the recipe by 5. 

So, I would actually be measuring and mixing the above recipe like this…

Base 4 
Base Glaze
Frit 3195
65
325g

Gerstly Borate
10
50g

Wollastonite
15
75g

EPK
10
50g


100
500g





Bentonite
2
10g




Colorants



Dark Brown
Red Iron Oxide
10
50g


Water is added until the desired consistency is reached. This is a matter of preference and application technique. I brush my glazes on super, SUPER thick, so my glazes are usually about the consistency of Greek yogurt.

I hope this answered a few of your questions and will help get you started if you're new to glaze mixing. If you have any other questions, please feel free to comment or email me. 

Cheers!
Meagan

4 comments:

Linda Starr said...

I like your blogs new look and I'm reading with interest your info about glazes, thanks.

Meagan Chaney said...

Thanks Linda! Glad you're liking the new blog look. I've been working behind the scenes (with lots of help!) and hope to have a new website ready next month as well. Stay tuned...

Kathy said...

In the Base 4 Glaze recipe which which particular ingredient is the glass former, the stabilizer and the flux? Thanks!

Meagan Chaney Gumpert said...

Hi Kathy,
I apologize for my delayed reply. I have moved my blog to a new address: www.MeaganChaneyGumpert.com/blog and I didn't see your comment right away.

In response to your question, Frit 3195 is the glass, Gerstley Borate a flux (though it has other properties as well), Wollastonie is also a flux, and the EPK is the stabilizer. Hope that helps!

cheers!