Category: Glaze > Iron > Celadon > Blue
Created 2016-08-11 01:15:50 by John Britt
Categories: Glaze > Iron > Celadon > Blue
Firing Temperature: Δ10
Atmospheres: Reduction
Surface Type: Glossy
Transparency: Translucent

From the Clayart archives:

http://www.potters.org/subject95906.htm

(Also found in John Britt's High Fire Glazes, p. 68)

Tom Buck on fri 1 sep 06

I assume you are firing to Cone 10 and in reduction part of the time, otherwise you would not be quoting from John Britt's book, one of the few places where my original Celadon glaze is cited.

I mostly do Cone 6 oxidation (+raku) these days but I did design the Celadon blue for Cone 10 with light or zero reduction. Black iron oxide (FeO) is a very stable compound in a Cone 10 firing but it will act
as a "flux oxide" and if present above a minimal level it will melt alumina and silica. Which is why so little black oxide is used in a celadon; half (maybe) acts as flux, half as colourant.

If you have spanish red iron oxide, be aware that it contains 83-87% by weight of Fe2O3 (iron oxide red) and so that lower Fe2O3 content has to be considered when you replace Black Iron Oxide, FeO, which is high grade probably close to 100% by weight. Also, if your yellow iron oxide is pigment grade (and not yellow ochre which contains some clayey material then it too is high grade close to 100% Fe2O3.H2O or hydrated red iron oxide.

So, try my recipe and use Yellow Iron Oxide (pigment grade) in place of the 1% by weight of Black Iron Oxide (FeO). If you wish to be precise, add 1.13% yellow oxide and you will get 1% FeO when reaching higher cones. The success of this glaze depends on your claybody and how you fire the ware.

If you have spanish red, 1.18% will equal 1% black oxide.

Celadon colours are "solution" colours, that is, the iron oxide will actually dissolve (as opposed to dispersion or suspension) in the Liquidus (molten glaze), and when cooled, the widely located iron oxide (FeO) molecules will reflect incident white light in green or blue wavelengths.

may your tests go well. peace Tom B.


From another thread in Clayart, Mike Gordon lists the recipe with Wollastonite rather than Whiting:

http://www.potters.org/subject115949.htm

Mike Gordon on mon 28 mar 11

TOM BUCK CELADON Cone 10
Custer Feldspar 30.00
Wollastonite 25.00
Grolleg Kaolin 21.00
Silica 24.00
Black Iron Oxide 1.00


From yet another thread, Tom seems to indicate that his celadon recipe does in fact use Wollastonite.

http://www.potters.org/subject35039.htm

Tom Buck on sun 21 jan 01

Perhaps you do not need this now. But I was doing some writing in Nov and had to put off some things. The basic problem with the Pinnell CB is WHITING, and 20 units is a lot of CO2 coming above 1800 F/1000 C. BTW Whiting is 44% CO2 and 56% CaO. You need a good soak to heal the burst bubbles, and where the glaze is thin healing may not occur even then.
The solution is to replace the Whiting with Wollastonite (CaO.SiO2) and when you do this the Silica/Flint needs changing too. here is how it comes out
30 Custer fs
25 Wollastonite
21 Grolleg
24 Flint
additives as before.
Molecularly, the two recipes provide the same amounts of fluxes and glass-formers. It still will be glossy and with the same expansion/contraction.
til later. Peace. Tom B.

Material Amount Batch Subtotal
Custer Feldspar 30
Wollastonite (Theoretical) 25
Silica 24
Grolleg Kaolin 21
Total Base:100
Black Iron Oxide 1
Total: 101

Percentage Analysis

Ingredient Amount SiO2 Al2O3 MgO CaO K2O Na2O KNaO FeO Fe2O3 TiO2 LOI
Custer Feldspar3020.555.10.0930.93.90.030.09
Wollastonite (Theoretical)2512.9312.07
Silica2424
Grolleg Kaolin2110.067.760.060.020.40.020.420.150.012.52
Black Iron Oxide10.260.660.08
Total10167.5512.860.0612.183.40.924.320.260.840.012.69
100% no LOI 68.8813.110.0612.423.470.944.40.270.850.01

Unity Molecular Formula (UMF)

FLUXES

RO/R2O

0.06 Na2O
0.13 K2O
0.8 CaO
0.01 MgO
STABILIZERS

R2O3

0.47 Al2O3
GLASS-FORMERS

RO2

4.17 SiO2
OTHER

 

0.02 Fe2O3
0.01 FeO
SILICA:ALUMINA

SiO2:Al2O3

8.91

FLUX RATIO

R2O:RO

0.19 : 0.81

SiO2:Al2O3 Chart

Closest 39 neighbors in Glaze > Iron > Celadon > Blue.

Click and drag to zoom
Stull Chart
SiO2:Al2O3 Ratio
SiO2:Al2O3 Ratio 8.91

Similar Base Recipes

Similar RO/R2O Unity Formulas

R2O3 - STABILIZERS RO2 - GLASS FORMERS RO/R2O - FLUXES
Recipe Name ΔTemp Al2O3 B2O3 SiO2 ZrO2 SnO2 TiO2 KNaO K2O Na2O CaO MgO ZnO BaO PbO Li2O SrO
Tom Buck Celadon (variation) 10 0.47 4.17 0.19 0.13 0.06 0.8 0.01
V&O Light Blue 9-10 0.5 4.12 0.19 0.13 0.06 0.81 0.01
Celadon Blue Green V&O 9-10 0.51 4.13 0.19 0.13 0.06 0.81
Clear Eva's 10 0.42 4.13 0.01 0.2 0.15 0.05 0.79 0.01
Blatant Blue 9-10 0.42 4.14 0.01 0.2 0.14 0.06 0.8 0.01
Pinnell Blue Celadon (+Titanium) 9-10 0.45 4.15 0.03 0.05 0.16 0.11 0.05 0.81 0.04
Pinnell Blue Celadon (+Cobalt) 9-10 0.45 4.15 0.03 0.16 0.11 0.05 0.81 0.04
PNW-Celadon 10 0.49 4.16 0.19 0.13 0.06 0.82
Tom Buck Celadon 10 0.47 4.17 0.19 0.13 0.06 0.8 0.01
Glaze Stone + Wollastonite 10-11 0.44 4.2 0.21 0.09 0.12 0.77 0.02
pinnel blue 10-12 0.48 4.21 0.16 0.11 0.05 0.83
VCU Celadon High Fire Glaze Base 9-10 0.5 4.21 0.18 0.12 0.06 0.82

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Hazards

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.
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)
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
Grolleg Kaolin 1 0 0 E
Black Iron Oxide Health Hazard WARNING May cause damage to lung through prolonged or repeated exposure by inhalation.