Lesson 5A - Glaze Formula to Batch Calculations

Learn to use a non-unity calculation to convert a formula into a batch recipe using theoretical and real-world materials. Retotal, round-off and make a side-by-side report.

D. Desktop Insight

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Shows you how to use a non-unity calculation and the supply button to convert a formula into a batch recipe. You will find out how to match a target formula exactly using theoretical materials and how to create a best match using real-world materials and the KNaO checkbox.You will also use the retotal and round-off function and the side-by-side report. The next chapter of the book deals with a more difficult conversion that requires an online search for a frit of specific chemistry to solve the problem.

Lesson 5A: Formula to Batch
Mon-unity calculations, the language of formulas, normalization, the formula to analysis dialog, supplying and re-supplying oxides, material ordering and material oxide sourcing, KNaO vs. K2O/Na2O, side-by-side reporting

Formula to Batch Derivation
Welcome. In this lesson we are going to learn how to do a formula to batch calculation.
We will cover non-unity calculations, the language of formulas, normalization, the formula to analysis dialog, supplying and re-supplying oxides, material ordering and material oxide sourcing, KNaO vs. K2O/Na2O, side-by-side reporting.

Speaking formulas
Many textbooks present glazes as formulas, instead of recipes. Their authors ‘speak the language of formulas’ when discussing glazes and relate fired properties to the presence, absence, amount and interplays of the oxides. They assume that you will select appropriate materials to source each oxide and that you know how to calculate the right amount of material. For example, what material do you want to supply CaO from and how much is needed?

Formulas don't belong in recipe list
This process can be tricky. I will first work through an example where everything works according to plan. Then I will consider a tougher one.
You cannot just type a formula into INSIGHT as a recipe. Why? Recipes express parts by weight, formulas compare numbers of molecules. INSIGHT’s Recipe List can only contain parts-by-weight.
There is a special dialog to convert a formula into an analysis (which technically is ‘a recipe of oxides’).

The Formula-to-analysis dialog
I have selected recipe 1 and chosen Enter Formula in the Calc menu and have keyed the formula into the Convert Formula to Analysis dialog.
Now I am going to click Done.

Use No-unity for formula to batch
INSIGHT converts the formula into an analysis and puts it into the Recipe List and then calculates the formula and puts it here.
To set things up I want to make sure Calculation Type is RO Unity for recipe 1 and No Unity for recipe 2 where I will be building the batch.
Why No Unity for recipe 2? If INSIGHT imposes unity each time the recipe changes all the formula numbers will be bouncing around. Furthermore, the Supply button needed for this process will not be available unless the recipe is set to no unity calculation.

Determine order to add materials
I need to determine which oxides to satisfy first.
It is easy to oversupply some oxides if I introduce materials in the wrong order. I will use the most complex material (the one supplying the most oxides) first: I will use feldspar to source Na2O/K2O.
Then wollastonite & whiting to supply CaO, dolomite for MgO, kaolin for Al2O3, silica to round out the SiO2 and zinc oxide for ZnO.

Supply Na2O first
First, I want to supply sodium and potassium.
I am going to use generic soda feldspar to satisfy the Na2O, and generic potash feldspar for the K2O. Remember that generic materials do not exist in nature, but for this demonstration they are a good starting point. I will use a real world material later.
I will point out also that I am still using the lessons materials table.
I need to unselect this checkbox, I want to see K2O and Na2O listed separately.
I have selected recipe 2, I am building it there.
I have also selected the first blank line in the Recipe List.

Enter source material, click Supply
I have entered “soda feldspar” (I just typed “soda f”) in the Lookup blank and clicked Update.
Now I have soda feldspar on a line with no amount. I need to click the line also since it moves down automatically each time I add a material to the list.
Instead of keying in an amount, I am going to click the Supply button.

Supply Oxide dialog
INSIGHT displays the Supply Oxides dialog. Notice that only oxides supplied by this material are available and INSIGHT shows the relative amounts of each that the material contains.
I have clicked the Na2O option button.
INSIGHT fills in the Molecules Needed blank with the amount of Na2O in the formula of target recipe 1. The Molecules Present blank shows how much has already been supplied by other materials in the recipe under construction; currently none.
I will Click Done.

Supply K2O from potash
INSIGHT calculates the right amount of soda feldspar to supply 0.1 Na2O. Notice that the feldspar also sources Al2O3 and SiO2.
Now I will supply K2O.
Click on the next empty recipe line, key “POTASH” and click Supply (notice that I do not have to click the update button before the Supply button).

INSIGHT calculates the correct amount
In the Supply dialog I’ll click the option button for K2O.
Then I will click Done and INSIGHT calculates the amount of potash feldspar needed to supply 0.15 molecules of K2O.

Supply MgO from Dolomite
Now I need to supply MgO from dolomite.
I will click the next blank recipe line, key “DOL” into the Lookup blank and click the Supply button.
In the Supply dialog I have selected the MgO option button and now I will click Done.

Three oxides are matched
Here is the result, INSIGHT has calculated the right amount of dolomite to supply 0.05 MgO.
I have three oxides matched now and part of the requirements for the others have been supplied (and thankfully not overshot).

Supply CaO from whiting
Next I will use the same process to supply CaO using Whiting. But notice the supply oxide dialog. As before INSIGHT knows how much CaO I want by looking at the target in Recipe 1. But it also knows now much has already been supplied by other materials.
I'll click done to establish the whiting amount and then supply the ZnO from zinc using the same process.

Supply Al2O3 from Kaolin
Now the formula and recipe look like this.
I have supplied all the fluxing oxides in the exact amounts needed, now we need alumina.
Kaolin is highly desirable in many types of glaze recipes because it aids suspension, dry hardening and other working and application properties. “0.4” molecules of Al2O3 are required, only “0.25” have been contributed from other materials.
I am going to click on the next available recipe line, enter “KAOLIN” in the Lookup blank and click supply.

Supply SiO2 from silica
In the Supply dialog I will click Al2O3 as the oxide to supply, then click Done.
I have done the same thing with SiO2 using silica as the supplier material.
The formulas now match.
Notice recipe 2 totals 379.59. This is the exact weight at which a nounity and unity formula are identical for this recipe. We call this a normalized recipe. I could now use the retotal item in the Calc menu to retotal it to 100 but I am not finished.

Using a name-brand feldspar instead
The feldspar I used was generic. I looked it up in the materials dialog, here it is. Notice the numbers are nicely rounded. Unfortunately real-world feldspars are not so simple.
Here is an example of a real feldspar. Almost all feldspars supply both K2O and Na2O and almost never in the proportions you need, so you have to be satisfied with matching the total of the two. You get other fluxes also, in this case, CaO.
I will therefore check the KNaO checkbox. This tells INSIGHT to combine the Na2O and K2O totals in the Formula List.
I will use Custer feldspar in place of potash and soda feldspars.

Replace the feldspars
First I will manually sum the total of the two feldspars. It is 136.
I will make sure recipe 2 is selected and delete the potash and soda feldspar lines by selecting each line and clicking the Delete button once to zero the amount and again to remove the line.
I will click the next blank line in the recipe and enter custer feldspar with an amount of 136.

Fine tune the new feldspar amount
If we compare these two formulas now you will see that while they are pretty similar there is a significant difference in the amount of KNaO contributed.
Now I have selected the feldspar line and I am going to fine tune the amount of Custer using the Increment and Decrement arrow buttons until the KNaO matches.
I am also going to check the three decimal button since this is a high total recipe where material amount changes do not impact formula numbers as much.

Accomodating the new feldspar
I stopped at 160 feldspar to get a perfect match on the KNaO. Or is it perfect? Notice what happens if I uncheck the KNaO checkbox for a moment. The individual amounts of K2O and Na2O do not match, but their totals do. This is the reality of using feldspars, fortunately K2O and Na2O have pretty similar effects on glazes.
Notice that the Al2O3, SiO2 and CaO are now all oversupplied because of the feldspar increase. I will resupply them now.

Resupply Al2O3
I'll click on the Al2O3 line in the formula list. Selecting this line does not really do anything, I just clicked it as a reference to what I am doing. If you teach INSIGHT you will want to do the same.
I'll click the kaolin in the recipe and then the Supply button. As you can see it is also a resupply button.
I have clicked the Al2O3 and notice that INSIGHT shows the Molecules already present as if there was zero kaolin.
I'll click Done.

Resupply SiO2 and CaO
Now I have the Al2O3 matched up again. Then I will do the same thing with the SiO2 from Silica and CaO from Whiting.

Retotal and round amounts
Now the formulas match again. This exercise helps us appreciate how different feldspars can be in their chemistry.
The recipe totals 379 so I will retotal it to 100 by choosing 'Retotal Recipe' in the Calc menu and then I will round it off by choosing 'Round Amounts' in the Calc menu. I am also going to uncheck the three decimal box, I don't need this accuracy anymore.

Restore RO unity
Now I have a 100 recipe total, at least almost 100. During the process of rounding to a tenth an over or undershoot of 0.1 can happen.
But there is another problem. What happened to the new formula, it does not match anymore? The problem is here, I need to set recipe 2 back to RO Unity (remember that when a recipe total changes so does its whole non unity formula). Here is the formula list again. It looks good.

Print side-by-side report
Wouldn’t it be nice to print a side-by-side report of these two recipes and their chemistry? I have done it here using this item in the Report Type menu. It compares the recipes as well as the formulas, analyses and mole percents. INSIGHT has templates for its reports (in the TEMPLATES folder) so you can change the layout and content.
Now, can you follow my example with the feldspar and substitute a much more chemically complex ball clay for the kaolin. The ball clay will give a completely different character to the working properties of the glaze slurry.

You might think this process should be more automatic. But there is no way a machine can chose the best materials in every situation. INSIGHT would create batches with the correct chemistry but they might be expensive, from difficult-to-get or inconsistent materials, have poor application, drying or suspending properties, exhibit problems with high LOI and gassing, etc. These considerations are complex and beyond software, at least now.
That is the end of this lesson.

Out Bound Links

  • (URLs) Tutorial Videos at Digitalfire


  • (Glossary) Unity Formula

    A "unity formula" is just a formula that has been retotaled so that the RO group of oxides totals one. This is also called a Seger formula and this standard provides one basis for comparing glazes. The three column format of expressing a formula was first used by Hermann Seger. The unity is normally...

  • (Glossary) Formula

    Conceptually we consider fired ceramic glazes as being composed of 'oxides' (materials contribute these). The ten major oxides likely make up 99% of all base glazes (and materials we use). The oxide formula of a glaze "explains" many details about the way the glaze fires (provided all the materials ...

In Bound Links

  • (Project) Ceramic Oxides Overview

    Ceramic formulation and adjustment technology can be approached on different levels: The pure oxide, the oxide in the presence of others with which to interact, the mineral, the material, the recipe a...

  • (Glossary) Batch Recipe

    The term 'batch' refers to the actual mixture of materials that you weigh out when you prepare a glaze or clay body batch for production or testing. The term 'recipe' is more correct than 'formula', the latter refers to the chemistry of the mix. Glaze software is used to calculate the chemistry of a...

  • (Glossary) Normalization
  • (Project) Glaze and Clay Body Recipes

    Recipes here are for demo purposes. Read the explanatory information about how to adjust, how it was formulated, links to similar ones, links to ones earlier or later in the series. There ar...

  • (Glossary) Digitalfire Insight

    A desktop application for Windows, Linux, Macintosh that you download and install. Insight is a classic glaze chemistry calculator. -It interactively converts recipes to formulas and back. The main Insight window shows side-by-side recipes and their formulas, you can make chemistry changes to one...

By Tony Hansen

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