This is an interesting website: www.glazesimulator.com which is free. It helps to combine glaze analysis software with an empirical approach for both glaze properties and color effects.
Developed by Fraser Forsythe he comments “About 10 years ago I wrote software called glazesimulator and sold it for about three years. It was profiled in Ceramics Monthly along with Insight and Matrix. I found that most people really don’t like calculation or chemistry in the same sentence as creative or art. I thought, fair enough. There is a more empirical approach to making and testing glazes exemplified in a book like the Ceramic Spectrum. The website is an attempt to combine the two approaches.
My goal for the next year or so is to get the site out there and people going to it regularly. I would like to develop the site in conjunction with feedback I receive. The suggestions links on the site do not generate revenue. They are intended to send users to resources that would help in the learning and research process. It is worth a look I suggest and i am sure Fraser would welcome any feedback.
I tried it and found it very helpful. It would be even better if European glaze materials were included.
Hi.
Thanks for checking out the site. I have had requests for non-north american materials several times. I am slowly compiling new material specs.
It would be a huge help if users who can’t find materials they use would email me with the material they are looking for.
Better yet if you could ask your local supplier for an analysis of the materials you use and send those along as well.
Thanks again for taking the time to look over the site!
Fraser
Hi Linda.
Thanks for taking a look at the website.
It is difficult to find material analysis used outside North America. Please forward any materials you use but can’t find on the site. It would be great if people using the site with similar concerns could contact their suppliers and ask for material analysis and then send that information.
Thanks again.
Fraser
These analyses are from Mike Bailey’s cone 6 glazes book
Calcium borate frit K2O .01 CaO .99 MgO .01 Al2O3 .1 B2O3 1.5 SiO2 .62 Mol. wt. 209
Standard borax frit K2O .04 Na2O .35 CaO .61 MgO .01 Al2O3 .18 B2O3 .62 SiO2 1.98 Mol.wt. 240
High alkaline frit K2O .21 Na2O.59 Li2O .01 CaO .1 BaO .09 Al2O3 .1 B2O3 .1 SiO2 1.71 Mol.wt. 196
Low expansion frit K2O .03 Na2O.2 CaO .76 MgO .01 Al2O3 .55 B2O3 1.02 SiO2 3.39 Mol.wt. 390
Percentage compositions of UK clays and feldspars from Mike Bailey’s Glazes cone 6 book
China clay SiO2 48.8 TiO2 .1 Al2O3 35.4 Fe2O3 .8 K2O 1.6 Na2O 1.5 LOI 11.8
AT Ball clay SiO2 54 TiO2 1.1 Al2O3 29 Fe2O32.4 CaO .3 MgO .4 K2O 3 Na2O .5 LOI 9.3
HP71 Ball clay SiO2 70 TiO2 1.6 Al2O3 19 Fe2O3 .8 CaO .2 MgO .4 K2O 2 Na2O .5 LOI 5.5
HVAR Ball clay SiO2 60.3 TiO2 1.5 Al2O3 26.7 Fe2O3 .9 CaO .2 MgO .3 K2O 2.6 Na2O .4 LOI 7.1
Cornish stone SiO2 73.2 TiO2 .06 Al2O3 15.3 Fe2O3 .13 P2O5 .47 CaO 1.47 MgO .13 K2O 4.45 Na2O 3.44 LOI 1.35
Nepheline syenite SiO2 60.5 Al2O3 23 Fe2O3 .1 CaO 1 K2O 5 Na2O 10.2 LOI .2
Potash feldspar SiO2 65.8 Al2O3 18.5 Fe2O3 .1 CaO .38 K2O 12 Na2O 2.89 LOI .33
Soda feldspar SiO2 67.9 Al2O3 19 Fe2O3 .11 CaO 1.88 K2O 2.8 Na2O 7.5 LOI .81
FFF feldspar SiO2 66.8 Al2O3 19 Fe2O3 .12 CaO .3 MgO .1 K2O 8.4 Na2O 5
This is from digitalfire.com
Regards,
Linda
Here is another analysis for FFF feldspar from David Hewitt Bath Potters Supplies
FFF feldspar SiO2 67.7 Al2O3 18.9 Fe2O3 .16 CaO .72 K2O 7.62 Na2O 4.85 LOI .05
http://www.bathpotters.co.uk/information/bps-raw-materials-data/53/
It would be most useful if you could put these on glaze simulator
Hi Linda. Thanks very much for sending this information.
There are several materials in your list that are in the glazesimulator.com database, but they have different names. Nepheline syenite is there and there is a potash and soda feldspar but I will check differences. Not sure but will check if Cornwall Stone is close to Cornish stone.
I will let you know when I’ve added them.
Thanks again!
Fraser
Hello again. Just to let you know the updates you’ve requested are online now. If I’ve goofed on something please let me know. I am slowly working toward having a locale sensitive option, so you can limit lists to materials in your part of the world. Be a bit longer with that.
Thanks.
Hello Fraser,
Thanks for putting those materials on the database. What’s the difference between calcium borate frit and BPS calcium borate frit? Are they the same? When I use calcium borate frit in the recipe (15%) the suggested firing temperature comes out very low (cone 04 -08) when actually I fire those glazes to cone 6-8.
The other thing I noticed was the expansion always comes out low, but that’s probably because I use porcelain.
It’s quite useful to have both US and UK materials when translating glaze recipes.
Best wishes,
Linda
I don’t think boron should be in the fluxes column, it should be with the alumina. This is quite important in calculating flux unity for determining whether glazes are within the limit formulas. Hesselberth and Roy put B2O3 with Al2O3 in their book Mastering cone 6 glazes. Could you change it in your flux unity calculation?
Thanks
Linda
The same goes for Fe2O3 and Cr2O3
TiO2 should be with SiO2
Linda
I’m not sure if the FFF feldspar is correct -the K2O seems very low
Linda
Hi Linda
I will try to address your questions and concerns. You are right about the Calcium borate frit and BPS version. I will remove the generic version (name) when i do my next addition to materials. Thanks for the heads up on that one.
Predicting melt with recipes is tricky. The view I’ve adopted (and it seems there is some disagreement out there) is that boron can be both a glassformer and a flux. At lower temps it can act as the glass in the matrix but at higher temps that job falls to the silica and boron acts as a flux. There are some suggestions that boron can act as both glass and flux in the same glaze. I may have the pgm display the b2O3 as a glass in lower temps in the future, however, this may lead to even more confusion.
If you wouldn’t mind sending your recipe to me to check I’d be better able to respond to your query about melt. It is possible that your glaze may melt over a wide range of cones. The pgm defaults to the lowest possible calculated melt. I have a copper red that works effectively at cone 4 and cone 9.
It is unlikely that the expansion values used in glazesimulator.com will correlate to other systems. It is a relative measure used to indicate the direction of change in expansion over various trials.
As for Fe2O3, Cr2O3 and TiO2, the pgm does not take these materials into account in calculating glaze properties. The nomenclature would lead one to believe they should be in similar columns however fe2O3 changes into different forms during firings depending on various factors (like reduction), and some of those forms act as a powerful flux. Titanium does not seem to act like alumina although it has been linked to promoting crystallization at excessive levels or when present in combinations, namely zinc.
FFF Feldspar entry was missing K2O. Thanks for letting me know.
There have been a couple of upgrades to the site over the past couple of months. The materials lists can now be specified geographically and most of the site is available in a variety of languages – thanks to Google Translate.