Friday, August 24, 2012

Low Fire Friday: Bonus Edition - Reader Results with Crawl

I recently received an exciting email from a reader who has been working with the Low Fire Crawl glaze I featured in January's Low Fire Friday segment.

Rand O'Brien from New Hampshire writes:

"I have been using your Magnesium crawl in raku with wonderful results. The spaces between the beads seal against carboning and the beads "stick" very well. Your dark Turquoise develops a beautiful luster in reduction."

How exciting! It wouldn't have occurred to me to try this same glaze with a different firing method, but Rand is getting beautiful results! Kudos to you!

Here's a re-posting of the Low Fire Crawl recipe Rand is referring too:

Crawl Glaze - Cone 04

Gerstley Borate            46.5
Magnesuim Carbonate 31.0
EPK                            18.6
Borax                            3.9
______________________
                                  100.0
+ Zircopax                     5.5

For color add...

Beige/pale yellow: + red iron oxide 1%
Dark turquoise/jade: + copper carbonate 5%
Light turquoise/jade: + copper carbonate 1%
To see glaze test tiles of this recipe fired to cone 04 check out the original LFF post

Rand, Thank you so much for sharing your results! That luster halo with the turquoise is amazing!

If anyone else has tried any of the Low Fire Friday glazes and would like to share how they've worked for you, email me at info@MeaganChaney.com and I'll be happy to put together a Bonus Edition featuring your work.

Cheers!
Meagan


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