iandol on thu 3 jul 03
As you say, when we use wood ash from any source where there is n o =
possibility of having an assay done it might as well be treated as a =
generic material. therefore, local variations will play a large part =
determining the eventual outcome.
If, as I do, you are using your own locally collected ash, then I =
suggest you do line blends with a variety of materials to begin with. =
Use various clays, spars, silica, local rock powder (Quarry Dust). These =
will assist you to make judgements about the next step. The ones with =
Clay give indications about the effects of increasing the Alumina =
content. You may find some excellent samples from simple mixtures. My =
next step would be do some 6 by 6 test tiles introducing clay, silica =
and a spar with the ash. On the tile place the Spar opposite the Ash and =
the Clay opposite the Silica. This enables you to see what takes place =
with a constant ratio of Fluxing agents as the Silica in a row of =
samples increases while the Alumina is decreasing.
Have fun with your work.
Ivor Lewis. Redhill, South Australia =20