Richard Aerni on sun 17 oct 10
I messed around with this back in the 1970s...
Portland cement will form a rivulet-like glaze from cone 9 on up. I =3D
can't remember what I cut it with, but the cement itself is high in =3D
calcium, which when melted has a high surface tension and causes the =3D
break up instead of the flow together of a melt of less significant =3D
surface tense glazes.
Color if I recollect, is a nondescript green. =3D20
I turned to wood ash.
Best,
Richard
Richard Aerni
Rochester, NY =3D20
www.richardaerni.com
David Woof on mon 18 oct 10
I messed with portland cement a bit too=3D2C way back when=3D2C but volcani=
c an=3D
d wood ash were more interesting at the time to me. As Richard remembers=
=3D
=3D2C it was green.=3D20
=3D20
Several years ago at a party I met a chemist from the local cement plant. =
=3D
My interest included picking his brains and the possibility of getting some=
=3D
clay samples from their pit. (The original portland formula contained cla=
=3D
y as well as the calcium.)
=3D20
He informed me that they did not mine the clay but now made the portland ty=
=3D
pe from shipped in bags of the minerals they needed. As expected=3D2C the =
fo=3D
rmula he rattled off included the theoretical for clay. The plant sits ne=
=3D
ar a large opened fireclay deposit and a range of hills containing deposits=
=3D
of lime=3D2C dolomite and gypsum. However the modern demands for higher t=
ec=3D
h cements now demand more quality control of the materials.
=3D20
It could be interesting to develop a cone 6 portland and ash glaze with a t=
=3D
ouch of cobalt.......and/or manganese. If anyone takes this on I'd like t=
=3D
o hear your results.
=3D20
On another note=3D3B Larry came in this evening=3D2C elated by the results =
from=3D
firing some of his pieces using my new "Woof Z-Mix" body in Don's latest f=
=3D
iring. They had that train chugging along at cone 13 and beyond. Will co=
=3D
ntinue to put Z-Mix thru its paces in late November when we fire a communit=
=3D
y=3D2C students=3D2C faculty and friends wood and salt firing at my place.
=3D20
David Woof
________________________
=3D20
Portland cement glazes
Posted by: "Richard Aerni" raerni@ROCHESTER.RR.COM=3D20
Date: Sun Oct 17=3D2C 2010 11:51 pm ((PDT))
=3D20
I messed around with this back in the 1970s...
Portland cement will form a rivulet-like glaze from cone 9 on up. I can't r=
=3D
emember what I cut it with=3D2C but the cement itself is high in calcium=3D=
2C w=3D
hich when melted has a high surface tension and causes the break up instead=
=3D
of the flow together of a melt of less significant surface tense glazes.
Color if I recollect=3D2C is a nondescript green.=3D20
I turned to wood ash.
=3D20
=3D20
=3D20
=3D
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