Tom Howard on sun 29 aug 99
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Would anyone be able to help me formulate an ash glaze? I'm a bit of a
delphinium nut, growing more than 200 from the best seed from the Delphinium
society in England, and would like to be able to immortalise my poor dead
flowers. I have burnt the old stems and now have about half a bucket of =
fluffy
ash, not much to waste. Could anyone 1, recommend a simple glaze - I've
checked the archives, haven't done ash glazes before, 2, suggest a way to =
get
delphinium blue, oxides?, stains? 3, would firing this in my coneart kiln =
to
=5E6 ruin the elements? I would abandon the project if so. Many thanks =
Frances
HowardDartmouth, Nova Scotia.
Martin Howard on mon 30 aug 99
Hello Tom and Frances
Look on page 139 of Ash Glazes by Phil Rogers.
There is a list of Ash Analyses. No delphinium, but a good idea of the
spread of ashes that are more or less known. Of course yours will be
different, because of the plants themselves, the soil in which they are
grown and the growing conditions of the season. There is the number of
times you sieve the dry material. We could all do with a collection of
ALL ash analyses, from human through the various animals to trees and
the non-woody plants.
Harry Fraser, in Glazes for the craft potter, says on page 73:-
"Ashes are so variable in composition that the best means of introducing
them into glazes is by a process of trial and error. A good starting
point would be to use a simple formula of 40 percent feldspar, 40
percent of wood ash, and 20 percent (ball)clay."
He then mentions adding a borax frit, colemanite or whiting, if it is
too matt or underfired.
If too shiny, introduce silica (flint) or china clay to make the melt
more refractory.
He adds that "40, 40, 20" glaze on page 130 as for 1260C, 2300F and
calls it Ash glaze semi-matt.
Now, to get the blues you want, almost certainly you will have to use
cobalt. The ash derivation gives us no idea of the colour of the glaze
at all, from what I have read. My willow glaze, so far, is poor white
and the oak a sort of yellow, neither of them very attractive. So I must
work on them and introduce other RMs.
Of course, using a good computer glaze program and entering the
composition of the ashes as RMs would then give you the details your
want and cut out a lot of the trial and error.
Is there a reasonably cheap, but good and reliable, service on the
mainland of Britain for analysing our ashes? If there were I would
certainly use it and I suspect you would as well.
Martin Howard
Webbs Cottage Pottery and Press
Woolpits Road, Great Saling
BRAINTREE
Essex CM7 5DZ
01371 850 423
araneajo@gn.apc.org
Carenza Hayhoe on mon 30 aug 99
One solution to your need for an ash recipe for delphinium ash would be
Robin Hopper's "Try it and see" ^6 fromula using your delphinium ash as the
extra flux:
Feldspar (any) 36
Ballclay (any) 12
Whiting 17
Flint or quartz 19
Any flux 17
Good luck - it would be good to know what you finally decide to do -
Carenza
At 13:41 29/08/99 EDT, you wrote:
>----------------------------Original message----------------------------
>------------------
>Would anyone be able to help me formulate an ash glaze? I'm a bit of a
>delphinium nut, growing more than 200 from the best seed from the Delphinium
>society in England, and would like to be able to immortalise my poor dead
>flowers. I have burnt the old stems and now have about half a bucket of
fluffy
>ash, not much to waste. Could anyone 1, recommend a simple glaze - I've
>checked the archives, haven't done ash glazes before, 2, suggest a way
to get
>delphinium blue, oxides?, stains? 3, would firing this in my coneart
kiln to
>^6 ruin the elements? I would abandon the project if so. Many thanks
Frances
>HowardDartmouth, Nova Scotia.
>
>
>
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