Bob Hanlin on tue 14 may 02
I use insight to calculate glazes and to check glazes that are published
here or in the pubs. I have mainly been using the program to find the
expansion of glazes so I'll know if they will craze on my clay body or not.
I understand that...however, the ratios are a mystery to me.
What do they mean? What can I know about the glaze from those? It seems
that someone told me that you could tell about texture and maybe more. I
want to know all I can before I test.
Si:Al..........?
SiB:Al.......?
Any enlightenment here would be very helpful.
Thanks
Bob Hanlin
In Oklahoma City, where it can't decide whether it wants to be winter or
sumnmer.
Craig Martell on tue 14 may 02
At 11:19 AM 5/14/2002 -0500, you wrote:
>Si:Al..........?
Hello Bob:
The above is the silica to alumina ratio. Silica is the glass former and
alumina is an amphoteric or stabilizing component of glazes. The higher
the silica to alumina in the ratio, the glassier and shinier the
glaze. Too much silica can reverse this. One of my brighter glazes has a
silica/alumina ratio of 12:1. When you get below 8:1 you are heading
toward matter, harder to fuse glazes.
>SiB:Al.......?
The above represents the silca plus boron to alumina ratio. Boron is
considered a glass former and well as a glaze flux. Boron glass is not as
hard and durable as silicate glass.
regards, Craig Martell in Oreg0n
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