Category: Glaze > Iron
Created 2015-07-23 09:23:27 by Glazy Admin
Categories: Glaze > Iron
Firing Temperature: Δ5-8
Atmospheres: Reduction
Surface Type: Glossy - Semi

Source/Alternate names: John Post revision of Buck Cream Breaking Red

Source/Alternate names: Clay Times July/August 2004

Firing Notes: cool maximum rate to 800C hold 1 hour

Notes: Alisa Clausen: a thick, covering semi gloss, cream where glaze is thickest and rust where the glaze is thinnest. This is a breaking
glaze, with distinct colour differences from thick to thin. Has shino-like flecked and speckled look where thickest.

Notes: John Post: a speckled rust glaze where thin, turning into a creamy beige glaze if it is applied more thickly. Great in combination
with Berry Rust. Works at cone 6-7. In reduction at cone 7 it turned an unattractive speckled grey. I tried using less tin in order to cut
the cost of the glaze, but the glaze was not opaque enough with 3% or 6% tin. At 9% the glaze was opaque, but did not have the
creamy brightness of the glaze with 13%. I also tried 15% superpax instead of the tin, but that glaze test turned the rust colour a dull
brown and the left the creamy areas looking dingy.

Material Amount Batch Subtotal
Frit 3134 30.6
Custer Feldspar 26.6
Silica 18.2
Wollastonite (Theoretical) 10.6
EPK 8.4
Strontium Carbonate 3.3
Talc (Theoretical) 2.3
Total Base:100
Tin Oxide 13
Red iron oxide 6
Total: 119

Percentage Analysis

Ingredient Amount SiO2 Al2O3 B2O3 MgO CaO SrO K2O Na2O KNaO P2O5 Fe2O3 TiO2 SnO2 LOI
Frit 313430.614.
Custer Feldspar26.618.224.520.082.660.83.460.030.08
Wollastonite (Theoretical)10.65.485.12
Strontium Carbonate3.32.320.98
Talc (Theoretical)2.31.460.730.11
Tin Oxide1313
Red iron oxide65.70.3
100% no LOI 52.936.66.090.649.822.323.45.720.024.990.0311.2

Unity Molecular Formula (UMF)



0.19 Na2O
0.09 K2O
0.07 SrO
0.6 CaO
0.05 MgO


0.22 Al2O3
0.3 B2O3


3.05 SiO2
0.26 SnO2


0.11 Fe2O3





0.28 : 0.72

SiO2:Al2O3 Chart

Closest 100 neighbors in Glaze > Iron.

Click and drag to zoom
Stull Chart
SiO2:Al2O3 Ratio
SiO2:Al2O3 Ratio 13.58

Similar Base Recipes

Similar RO/R2O Unity Formulas

Recipe Name ΔTemp Al2O3 B2O3 SiO2 ZrO2 SnO2 TiO2 KNaO K2O Na2O CaO MgO ZnO BaO PbO Li2O SrO
Cream Breaking Rust 5-8 0.22 0.3 3.05 0.26 0.28 0.09 0.19 0.6 0.05 0.07
Cream Breaking Rust, ^6 6 0.23 0.3 3.05 0.26 0.28 0.09 0.19 0.6 0.05 0.07
Cream breaking brown WWW 264 6 0.26 0.29 3.1 0.29 0.3 0.25 0.05 0.56 0.06 0.07

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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
Custer Feldspar HarmfulHealth Hazard WARNING May cause damage to lungs through prolonged or repeated inhalation.
Suspected of causing cancer through
prolonged or repeated inhalation.
May cause allergy or asthma symptoms or breathing difficulties if inhaled.
May cause skin or eye irritation.
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
Wollastonite (Theoretical) Health Hazard DANGER Vansil W-30 Wollastonite SDS:
May cause cancer if inhaled.
Causes damage to organs through prolonged or repeated exposure if inhaled. (respiratory tract)
EPK HarmfulHealth Hazard DANGER 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
1 0 0 E
Strontium Carbonate Harmful WARNING Product dust may be irritating to eyes,skin and respiratory system.  1 0 0 E
Talc (Theoretical) Harmful WARNING Causes mild skin irritation
Harmful if inhaled
May cause respiratory irritation
1 0 0 E
Tin Oxide Harmful WARNING Harmful if swallowed.
Red iron oxide Health Hazard WARNING May cause damage to lung through prolonged or repeated exposure by inhalation