Category: Glaze > Clear
Created 1997-01-26 08:00:00 by Glazy Admin
Categories: Glaze > Clear
Firing Temperature: Δ7-8
Atmospheres: Oxidation, Reduction
Surface Type: Glossy
Transparency: Transparent

Glaze Type: Mid-fire
berry rust: 10% red iron oxide
deep river red: 20% RIO
midnight blue: 5% cobalt carb., 2% RIO, 1% copper carb.
silver yellow: 6% vanadium oxide, touch of rutile
majolica: 7% tin oxide
By itself without colorants, this glaze is fairly clear, not
perfectly transparent at cone 6-7 but becoming glass like at 8-9.
It is smooth to the touch, pleasing to feel. Very tolerant and
It is somewhat uninteresting by itself although it is as stable as
you can imagine.
Add colorants for the real action!
*How long have you been using this glaze?
8-10 years
*Where is it used? Bob Kavanagh's studio.
*Where did this recipe come from? I developed it over a few years.
*What do you like most about this glaze? It is stable, adaptable, accepts diverse
colors well, applies easily, is virtually fault free - a good friend.
*Does this glaze tend to craze/crawl/pinhole/etc.?
With the majolica, it may crawl if the glaze is applied VERY thickly.
*How do different firing temperatures/atmospheres affect the glaze?
It may be used in reduction as well as in oxidation, although I now
use it only in oxidation. I developed it while I was working in a
reducing atmosphere. The differences between oxidation and reduction
lie in the clarity of the glaze (much clearer in oxidation) and of
course the impact of reduction on iron bearing oxides.
*How does the glaze behave on different clay bodies?
Very adaptable to stoneware, porcelain, rough, smooth, etc.
*What consistency should the glaze be for pouring/dipping?
Dip hand into bucket; can hardly see skin under glaze on hand: thick
*How thickly should the glaze be applied to the pot?
Varies with oxide addition. Likes to be moderately thick for
richest results.
*How does this glaze interact with other glazes?
I had not been happy with combining it with others, so I stopped. It
can be layered with itself with different colorants in each layer.
*What is your kiln type and size?
10 cubic foot, Tucker's Cone Art, electric
*How do you typically fire?
0 to 212 in two hours: hold 10 minutes.
212 to 1040 at about 300 degrees an hour.
very slowly from 1040 to 1070.
as quickly as possible from 1070 to 2100.
about 150 degrees an hour until cone 7-8.
*Do you experience problems with the raw glaze?
no problems
*GlazeBase recipe*
Submitted by: bob kavanagh

Material Amount Batch Subtotal
Silica 27.3
EPK 18.2
Nepheline Syenite (Theoretical) 18.2
Bone Ash 9.1
Dolomite 9.1
Gerstley Borate 9.1
Talc (Theoretical) 9.1
Total: 100.1

Percentage Analysis

Ingredient Amount SiO2 Al2O3 B2O3 MgO CaO K2O Na2O KNaO P2O5 Fe2O3 TiO2 LOI
Nepheline Syenite (Theoretical)
Bone Ash9.15.083.860.16
Gerstley Borate9.11.350.092.440.321.770.040.360.
Talc (Theoretical)9.15.772.90.43
100% no LOI 59.9812.412.725.8510.911.042.413.454.360.220.09

Unity Molecular Formula (UMF)



0.1 Na2O
0.03 K2O
0.5 CaO
0.37 MgO


0.31 Al2O3
0.1 B2O3


2.56 SiO2


0.08 P2O5





0.13 : 0.87

SiO2:Al2O3 Chart

Closest 100 neighbors in Glaze > Clear.

Click and drag to zoom
Stull Chart
SiO2:Al2O3 Ratio
SiO2:Al2O3 Ratio 8.2

Similar Base Recipes

No recipes with similar base ingredients and amounts were found.

Similar RO/R2O Unity Formulas

Recipe Name ΔTemp Al2O3 B2O3 SiO2 ZrO2 SnO2 TiO2 KNaO K2O Na2O CaO MgO ZnO BaO PbO Li2O SrO
Clear bob's base 7-8 0.31 0.1 2.56 0.13 0.03 0.1 0.5 0.37
Berryrust 7-10 0.31 0.1 2.56 0.13 0.03 0.1 0.5 0.37
Brian Jones 2017-12-25 18:15:29
Wonder c8 glaze in oxidation. Makes nice saturated iron glaze given high P2O5 bone ash.


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
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
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
Bone Ash
Dolomite Health Hazard DANGER May cause cancer (Inhalation) 1 0 0 E
Gerstley Borate
Talc (Theoretical) Harmful WARNING Causes mild skin irritation
Harmful if inhaled
May cause respiratory irritation
1 0 0 E