Category: Glaze > Specialty > Crater
Created 2016-04-19 17:08:03 by kenneth ibbett
Categories: Glaze > Specialty > Crater
Firing Temperature: Δ6-8
Atmospheres: Oxidation
Surface Type: Matte
Transparency: Opaque

This is a base recipe for Volcanic glazes given to me by my teacher Akiko Hirai. She recommends using it on stoneware with a black slip underneath but it responds well to other additives ie 2-3% copper oxide turns it turquoise and on porcelain it looks like coral encrustations.

Material Amount Batch Subtotal
Nepheline Syenite (Theoretical) 60
Barium Carbonate 18
Kaolin (Theoretical) 11
Silica 10
Silicon carbide 2
Rutile 2
Total: 103

Percentage Analysis

Ingredient Amount SiO2 Al2O3 MgO CaO BaO K2O Na2O KNaO Fe2O3 TiO2 LOI
Nepheline Syenite (Theoretical)6036.4213.980.060.422.765.888.640.060.42
Barium Carbonate1813.984.02
Kaolin (Theoretical)115.24.421.38
Silicon carbide23
100% no LOI 55.6318.740.060.4314.242.815.998.80.261.83

Unity Molecular Formula (UMF)



0.42 Na2O
0.13 K2O
0.41 BaO
0.03 CaO
0.01 MgO


0.8 Al2O3


3.83 SiO2
0.1 TiO2


0.01 Fe2O3





0.55 : 0.45

SiO2:Al2O3 Chart

Closest 3 neighbors in Glaze > Specialty > Crater.

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Stull Chart
SiO2:Al2O3 Ratio
SiO2:Al2O3 Ratio 4.76

Similar Base Recipes

No recipes with similar base ingredients and amounts were found.

Similar RO/R2O Unity Formulas

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Coco Chanelle 2017-05-18 01:49:09
It's super nice, but it end up green-turquoise ish, like the second photo. Actually it looks like lichen, moss or rusty cooper


09/2016 Note: This is a new feature. If a recipe material is not listed, that material's data has not yet been added. Some materials only have GHS ratings, while others only have HMIS ratings. Warnings differ between systems and countries. Glazy does not take any responsibility for accuracy of linked SDS information. Contact your ceramics supplier for safety information for your specific materials.
Globally Harmonized System (GHS) Hazardous Materials Identification System (HMIS) SDS Link
Material Pictograms Signal Word Hazard Statements Health Flammability Hazard Protection
Barium Carbonate Harmful WARNING Harmful if swallowed. 2 0 1 *
Kaolin (Theoretical) HarmfulHealth Hazard DANGER SDS for EPK KAOLIN: EPK Kaolin is a naturally occurring mineral, which may contain amounts of crystalline silica
typically 0.1-1.0%, may cause damage to respiratory system through prolonged or repeated
Silica HarmfulHealth Hazard DANGER From 200-Mesh SDS:
May cause cancer by inhalation.
Causes damage to lungs through prolonged or repeated exposure by inhalation.
* 0 0 E
Silicon carbide Health Hazard WARNING May cause cancer
Rutile 1 0 0