Analysis to Formula Glaze Chemistry Calculations

[Tom Humphries]

Hi Guys,

I've been looking into glaze chemistry, reading some of the digital fire docs and other sources. I've been trying to create a spreadsheet where I take a percentage based glaze analysis, and convert it to the finished formula, which I should be able to compare with the known formula.

Anyway, So far I managed to get three of the ingredients converted to a flux unity formula which matches the formula I can find on digital fire etc. (wollastonite, frit 3134, F4 Feltspar). 

The calculated value for Kaolin is nowhere near the known values. Silica breaks because the lack of flux results in division by zero. I have tried calculating quartz and other low flux materials and the results all come out wrong.

I'd really appreciate some one taking a quick look at the spreadsheet attached. Am I doing something wrong, or is it not possible to convert some materials in this way?

Thanks a lot

Tom

[Nadine Mercader]

Tom,
The Glaze Master software is a far better use of your time, he values for all ingredients are included in the database and it also allows you to add new ingredients with the data from MSDS From your supplier. The software provides a 60 day evaluation for free to allow you to learn it. It is very simple and yet powerful. It was created by The same guys as the book MASTERING Cone 6 glazes. The evaluation version allows full function, saving, printing,etc...Save yourself some grief and try it out.

[Tom Humphries]

Thanks Nadine. I was going to look at glaze software, I just thought I would try prove the basics to myself first. I will still try figure this out. 

[Norm Stuart]

I use the Digitalfire Insight glaze calculation program for most things.  But I don't know of a glaze calc program which will solve for substitutions - that you have to do yourself.

So I sometimes find I get a better idea of what materials I need to use when I have their chemistry laid out in an Excel spreadsheet, somewhat like what you're doing.  I use the spreadsheet to develop chemically identical glazes made with different ingredients, then I check my answer with the Insight program.

It's sort of like working out a crossword puzzle - using an ingredient to provide enough of one oxide can provide an excess of others.

As an example, Alisa Clausen has posted photos of glazes made with frits like MOK-623 which are available in Scandinavia but not in the US.  So I used this spreadsheet approach to a find additions I could make to Ferro Frit 3134 to approximate Mok-623.

In this spreadsheet I've entered the chemistry breakdown in Digitalfire, hopefully correctly, then I multiply the percentage value I propose using in column F and multiply by each oxide the ingredient contains.  I sum each column for the rows of the original I'm trying to match, and sum the rows I'm creating to make an nearly identical chemistry.

This website is also useful to give me ideas.  http://www.glazesimulator.com/recWizardCreate.php

[Tom Humphries]

Norm, this is why I started the spreadsheet, because in the UK different Feldspars, Frits etc are available with slightly different oxide compositions, and I wanted to make an accurate version of glazes I have found to test.

From your sheet it looks like you're just added the percentages. I was under the impression they must be converted to unity formula versions first, is this not the case? 

I need to go to work now, but will have a better look at your sheet when I get back. 

Thanks!

[Nadine Mercader]

Tom, The Glaze Master software does allow for substitutions as well as allowing one to enter new materials with their specific data. I have used Excel spreadsheets as well but I found this software far easier. Good luck with it.

Tom Humphries said:

Thanks Nadine. I was going to look at glaze software, I just thought I would try prove the basics to myself first. I will still try figure this out. 

[Norm Stuart]

Herman Seger's Unity formula approach is helpful if you're trying to formulate a functionally similar glaze, and glaze software makes this easy.  I use Digitalfire Insight software, primarily to predict COE, primarily because it's free with a Digitalfire membership - and I use the Digitalfire all the time. 

If you're formulating a chemically-identical glaze, sourced from different ingredients, Seger's unity approach merely offers you additional work without additional benefit and software still leaves you with trial and error.

Different raw materials melt differently, so I've found it useful to put "chemically identical" ^6 glaze tiles into a bisque to get a better idea of what changes are occurring on the way to ^6.

Tom Humphries said:

Norm, this is why I started the spreadsheet, because in the UK different Feldspars, Frits etc are available with slightly different oxide compositions, and I wanted to make an accurate version of glazes I have found to test.

From your sheet it looks like you're just added the percentages. I was under the impression they must be converted to unity formula versions first, is this not the case? 

I need to go to work now, but will have a better look at your sheet when I get back. 

Thanks!

[Tom Humphries]

Thanks Norm, that makes sense.

I have now used similar spreadsheets to the one you posted to do my ingredient substitutions. I'm within 1% of each oxide which I guess is good enough to get started. That glaze simulator link is great too.  I will probably do the trial for Glazemaster too Nadine. I look forward to doing some testing in the near future - I need to go and buy some ingredients!