Seger devised the Unity Formula system ceramic scientists and educationalists
have conducted many tests to discover the upper and lower 'limits'
for the various oxides which may occur in a glazes fired to a particular
have usually been in the employ of one or other section of the ceramic
industry or are members of the ceramic education fraternity and
have conducted their tests with the requirements of that background
In the cases
of industry they have been concerned with the creation of glazes
which are durable and stable and which do not have problems such
as the leaching of constituent base oxides or colourants whereas
when educationalist or ceramic artist have devised limits they may
have been more concerned with producing a range of textures and
qualities of use in finishing non-functional ceramics.
there are a number of limit tables available to studio potters and
your choice of which limit tables to use must depend on your requirements.
If you are producing functional ware then issues of durability,
stability, fit, leaching etc will be of importance and may determine
which limit tables you should use. These tables will have a much
smaller range of, e.g. acceptable Al2O3 and SiO2 limits, than glazes
which are not being used as liners in table ware.
Tables Available in Matrix
with a number of limit tables gathered from various sources. These
tables may be viewed and edited in the Limits Chart Window.
New tables may
be developed and saved from this window.
may also be viewed on the Limit Formula Graph and on the Al / Si
Graphs in which the tables displayed may be selected from the windows'
is booted it will check it's Matrix Options.opt file to see
which set of tables to initially use in limit displays.
You may change
this default setting by selecting the Options
(Preferences) item in the Matrix menu and clicking the
Limits tab. More ...
Your Own Limit Tables
You may wish
to experiment with the creation of specific limits data which reflect
oxide ranges in particular glaze types e.g. maiolica, shino, oilspot,
etc., etc. This process is explained in Creating Your Own Limits
these links for more information about: