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3D Print a Test of the Beer Bottle Neck
3D Printing a Clay Cookie Cutter-Stamper
A 3-minute Mug with Plainsman Polar Ice
A Broken Glaze Meets Insight-Live and a Magic Material
Accessing Recipes from "Mid-Fire Glazes" book in Insight-Live
Adjusting the Thixotropy of an Engobe for Pottery
Analysing a Crazing, Cutlery-marking Glaze Using Insight-Live
Compare the Chemistry of Recipes Using Insight-Live
Connecting an External Image to Insight-Live Pictures
Convert a Cone 10 Glaze to Cone 6 Using Desktop Insight
Create a Synthetic Feldspar in Insight-Live
Creating a Cone 6 Oil-Spot Overglaze Effect
Creating Rules for Calcium Carbonate - Wollastonite Substitution
Design a Triangular Pottery Plate Block Mold in Fusion 360
Desktop Insight - Difficult Formula to Batch Calcuations
Desktop Insight 1A - Compare Theoretical and Real-World Feldspars
Desktop Insight 1B - Turn a Feldspar Into a Glaze
Desktop Insight 1C - Substitute Wollastonite for Whiting in Glazes
Desktop Insight 2 - Creating a Matte Glaze
Desktop Insight 3 - Dealing With Crazing
Desktop Insight 4 - Add a Native Material to MDT, Build a Glaze
Desktop Insight 5A - Glaze Formula to Batch Calculations
Desktop Insight MDT: Adding a Material
Desktop Insight: Maintain an MDT as a CSV File in Excel
Digitalfire Desktop INSIGHT Overview Part 1
Digitalfire Desktop INSIGHT Overview Part 2
Enter a Recipe Into Insight-live
Entering Shrinkage/Porosity Data Into Insight-Live
Getting Frustrated With a 55% Gerstley Borate Glaze
How I Fixed a Settling Glaze Slurry Using Desktop Insight
How I Formulated a Cone 6 Silky Matte Glaze Using Insight-Live
How to Add Materials to the Desktop Insight MDT
How to Apply a White Slip to Terra Cotta Ware
How to Paste a Recipe Into Insight-live
Importing Data into Insight-live
Importing Desktop Insight Recipes to Insight-live
Importing Generic CSV Recipe Data into Insight-Live
Insight-Live Meets a Silica Deprived Glaze Recipe
Insight-Live Quick Overview
Liner Glazing a Stoneware Mug
Make a precision plaster mold for slip casting using Fusion 360 and 3D Printing
Make test bars to measure pottery clay physical properties
Making ceramic glaze flow test balls
Manually program your kiln or suffer glaze defects!
Mica and Feldspar Mine of MGK Minerals
Predicting Glaze Durability by Chemistry in Insight-Live
Preparing Pictures for Insight-live
Remove Gerstley Borate and Improve a Popular Cone 6 Clear Glaze
Replace Lithium Carbonate With Lithium Frit Using Insight-Live
Replacing 10% Gerstley Borate in a clear glaze
Signing Up at Insight-live.com
Signing-In at Insight-live.com
Slip cast a stoneware beer bottle
Subsitute Gerstley Borate in Floating Blue Using Desktop Insight
Substitute Ferro Frit 3134 For Another Frit
Substituting Custer Feldspar for Another in a Cone 10R Glaze Recipe
Substituting Materials by Weight: Why it does not work!
Substituting Nepheline Syenite for Soda Feldspar
Thixotropy and How to Gel a Ceramic Glaze
Use Insight-live to substitute materials in a recipe
Using Recipe Libraries With Desktop Insight

Replacing 10% Gerstley Borate in a clear glaze

Video coming soon.

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Please follow transcript instead.

Glazes can be viewed as mixtures of ceramic minerals and manufactured ceramic powders. Each material contributes its chemistry to melt. The overall chemistry determines fired properties. Boron, or B2O3, is an oxide, it is sourced by Gerstley Borate. Boron is a low melting glass, thus it reacts well with other oxides like SiO2, Al2O3, CaO, etc. to produce ceramic glazes that melt at low temperatures. Reducing and increasing individual oxides has much more predictable effects than manipulating the amounts of the materials. Thus, rather than use a GB substitute, it is better to remove it from each glaze, add boron and calcium sources and juggle the remain materials to restore any disruption in other oxides.

Consider an example, Ron Roy's Clear Glaze.

    F-4 FELDSPAR      31.00  CaO    0.66*
    SILICA            21.00  MgO    0.12*
    FRIT 3134          5.00  K2O    0.05*
    GERSTLEY BORATE   10.00  Na2O   0.17*
    EPK KAOLIN        17.00  Al2O3  0.41
    WHITING           13.00  B2O3   0.20
    TALC               3.00  SiO2   3.05

This contains a smaller amount of GB and part of the boron is sourced from a frit. In addition, the 17% kaolin is adequate to suspend the slurry, so removing the GB will not be as big an issue for the in-the-bucket properties. Using INSIGHT software I first removed the GB and increased the frit to bring the B2O3 back into line. Finally, I increased the talc slightly to make up for a loss in MgO and the kaolin to restore the Al2O3, and reduce the silica to bring the SiO2 down to match. Here is the adjusted recipe:

    F-4 FELDSPAR   31.00  CaO    0.63*
    SILICA         18.50  MgO    0.12*
    FRIT 3134      19.50  K2O    0.05*
    EPK KAOLIN     21.00  Na2O   0.20*
    WHITING        13.00  Al2O3  0.41
    TALC            4.50  B2O3   0.20
                ========  SiO2   3.06
                  107.50

I have not re-totaled to 100. I have not taken the trouble to match all of the oxides exactly. This is an inexact science anyway. This approach to removing GB from this particular glaze has worked very well.

Now consider a more complicated GB removal challenge.

    Nephy Syenite       47.30  CaO    0.41*
    Gerstly borate      27.50  MgO    0.10*
    Silica              22.30  K2O    0.09*
    EPK                  5.40  Na2O   0.40*
                     ========  Al2O3  0.51
                       102.50  B2O3   0.44
                               SiO2   3.55

This recipe relies almost entirely on GB to suspend it. If we try to substitute a frit the resultant mix won't suspend. Much more Ferro Frit 3134 is needed to supply the same amount of boron as the GB. Nepheline Syenite was reduced (and therefore the alumina it contributed). After supplying lost MgO from talc I increased the kaolin to both source Al2O3 and suspend the slurry. It all works out surprisingly well.

    Nephy Syenite.......   47.30  46.15%     25.43  25.43%
    Gerstly borate......   27.50  26.83%
    Silica..............   22.30  21.76%     14.68  14.68%
    EPK.................    5.40   5.27%     20.65  20.65%
    FRIT 3134...........                     36.02  36.02%
    TALC................                      3.23   3.23%
                        ========          ========
                          102.50            100.00

                       CaO  0.41*  6.47%      0.48*  7.52%
                       MgO  0.10*  1.08%      0.10*  1.12%
                       K2O  0.09*  2.43%      0.05*  1.26%
                      Na2O  0.40*  6.98%      0.38*  6.59%
                     Al2O3  0.51  14.54%      0.51  14.68%
                      B2O3  0.44   8.55%      0.44   8.54%
                      SiO2  3.55  59.84%      3.56  60.27%

Notice that the CaO and KNaO do not match exactly. This is as close as we can get them using this selection of materials. However we can make another couple of changes, using Wollastonite rather than whiting to source CaO and Nepheline Syenite to source of alkalis. Notice that the kaolin is higher so this new recipe will be an even better duplicate of the suspension and hardening properties of the original kaolin/GB combination.

    F-4 FELDSPAR........   31.00  31.00%
    SILICA..............   21.00  21.00%     17.09  17.09%
    FRIT 3134...........    5.00   5.00%     19.23  19.23%
    EPK KAOLIN..........   17.00  17.00%     23.93  23.93%
    WHITING.............   13.00  13.00%
    TALC................    3.00   3.00%      4.27   4.27%
    GERSTLEY BORATE.....   10.00  10.00%
    WOLLASTONITE........                     16.67  16.67%
    NEPHELINE SYENITE...                     18.80  18.80%
                        ========          ========
                          100.00            100.00

                        CaO  0.66* 12.37%      0.66* 12.44%
                        MgO  0.12*  1.57%      0.11*  1.51%
                        K2O  0.05*  1.73%      0.03*  1.02%
                       Na2O  0.17*  3.61%      0.20*  4.13%
                       TiO2  0.00   0.07%      0.00   0.09%
                      Al2O3  0.41  14.17%      0.41  13.94%
                       B2O3  0.20   4.58%      0.20   4.60%
                       P2O5  0.00   0.05%      0.00   0.06%
                       SiO2  3.05  61.66%      3.06  62.00%

To sum up, here are some things to keep in mind when rationalizing your glaze during the GB substitution process.

By Tony Hansen
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