Paul Borian on mon 31 may 10
thanks for the replies.
my main problem is really with the application. I have been using this ash
glaze for a long time and typically mix about 25 gallons at a time, adding
about 4% and some of axner's "flocs", plus i add cmc powder as needed which
i think helps the glaze stick to the pots after being sprayed on without
cracking and flaking off when it dries. This worked fine until i mixed a ne=
w
batch from a different stash of ash since my old stash was used up.
now the new batch of glaze has this cracking problem no matter how much or
how little cmc i add.
i keep this glaze very thick in the bucket because extra water makes the
problem worse. If the glaze was any thicker it would not spray at all yet i
still have this problem.
does anyone know of another solution to this problem, other than switching
to a fake ash? the idea of adding portland cement sounds interesting but i
am concerned that one day i would find a bucket of hardened cement when i
really needed to get work done.
thanks,
Paul
---------- Forwarded message ----------
From: Eric Hansen
Date: Mon, May 31, 2010 at 5:18 PM
Subject: Re: Reverse engineering hardwood ash?
To: Clayart@lsv.ceramics.org
Amen; before giving up on wood ash look at Aerni's site:
http://www.richardaerni.com/
Washing ash will remove the soluble alkalies, the caustics, yes. Washing
also allows finer screening of the ash. 40 mesh is good for me but some
might prefer 100 mesh. Ball-milling is even better. You might also want to
standardize each ash product. Such as, firewood, fruit tree wood prunings,
rice hull or rice straw, reed ash, bracken ash. Wood has the smallest retur=
n
percentage wise, most of it burns off. Grasses can yield many times the
amount of ash per pound. Also consider a standardized way of cooking ash.
Such as Gary Navarre's Koie Cooker:
http://www.google.com/search?q=3DKoie+cooker&hl=3Den&client=3Dsafari&rls=3D=
en&prmd=3Dv&source=3Duniv&tbs=3Dvid:1&tbo=3Du&ei=3DjCEETOWzAcWblgf_k-iBDQ&s=
a=3DX&oi=3Dvideo_result_group&ct=3Dtitle&resnum=3D4&ved=3D0CDMQqwQwAw
Also there are ways to tame the ash glaze using certain percentages of
feldspars and clays in addition to the ash.
h a n s e n
p.s. using the UPA to reconstruct a chemically identical formula will work,
however the results will be different with every substitution you make. How
different will depend on which substitutions they are.
On Mon, May 31, 2010 at 10:01 AM, David Beumee wrote=
:
> What I read is that the basic problem is that the ash is caustic, easily
> remedied by washing out the soluble alkalis.Yes, it will change the look
of
> the glaze, but you have a better chance of retaining the subtle qualities
> of
> your particular ash by fixing the problem than by trying to reproduce
> nature
> through chemical analysis and the UMF.
>
> David Beumee
> Lafayette, CO
>
>
>
>
>
>
>
>
>
>
>
>
> On Sun, May 30, 2010 at 12:17 PM, Paul Borian > >wrote:
>
> > i have been using hardwood ash in one of my glazes for years and it is =
a
> > major part of my product line.
> > however, i have never like working with it because it is caustic and it
> > presents numerous glaze application problems.
> > i know there are fake ash glazes out there but it would take a lot of
> time
> > to seek them out and test them all and hope i find one that looks the
> same.
> > So, i was thinking to send a sample of the hardwood ash i currently use
> off
> > to a lab to get the chemical analysis. With that info, would it be
> possible
> > to reformulate it as a fake ash glaze by making the necessary
substitions
> > to
> > get a glaze with the same unity formula?
> > Basically i just want to come up with a substitute for wood ash with th=
e
> > same chemical analysis as the ash i currently use.
> > Possible or impossible?
> > anyone care to comment?
> > thanks,
> > Paul
> >
>
Paul Borian on mon 7 jun 10
Phil,
thanks for the info. I would like to hear about your simpler method for
washing ash if you do care to elaborate.
the problems you describe are exactly what happened to my glaze, but i am
still using it and the pots look the same as always. It's just that the mos=
t
recent batch i mixed, using a newer supply of ash, seems more prone to this
problem than ones in the past.
the solution, for now, is too skim all the water off the top of the glaze
bucket so the glaze is very thick. But, it still seems quite wet as it is
applied (by spraying) and it is more of an inconvenience than a problem at
this point.
i have never washed the ash i use but it seems like this may be a good time
to start.
thanks,
Paul
---------- Forwarded message ----------
From: phil rogers
Date: Sun, Jun 6, 2010 at 3:48 AM
Subject: Reverse engineering hardwood ash?
To: Clayart@lsv.ceramics.org
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Washing ash will not remove all the alkaline
soluble fluxes...washing twice or three times is sufficient to remove enoug=
h
alkaline to render the ash useful. If you are having
application problems it is likely that it is because you haven't washed it
all
or not enough. All of these issues are dicussed in my book ASH GLAZES. You
will
see that I recomend washing. I know there are potters who don't wash but
there
is always the risk of the glaze batch spoiling due to excess alkaline in
solution. The effect is a jelly like formation that makes the glaze appear
to be
thick. The addition of more water until the glaze looks like it is right
only
produces a very thin coating when a pot is dipped. There is far too much
water
in the suspension BUT it appears to look right. after this effect has
happened
one might as well throw the batch away as it is, to all intent and purpose,
irreversable. Additons of acids like vinegar or Calcium Chloride can make a
difference but it is temporary.
Washing ash need not be a huge chore...I have developed a method that is
quick and only a minor inconvenience. If anyone is interested I can
elaborate on that later.
Unless you really want to do it there is no real
advantage in finding the chemical analysis of your ash. Any ash can be used
succesfully...it just needs to be prepared properly. Again, there is a
chapter
on 'fake ash glazes' in ASH GLAZES. ( I was reluctantly persuaded to includ=
e
it!!)
To me at least, the beauty of ash as a material is
that it is a natural product and one should enjoy the slightly unpredicatbl=
e
nature of the material. If you require a standardised product then go ahead
and
produce a 'fake ash' but it is moving away from the very real character of
ash
and the reasons why I,at least, use it.
PHIL ROGERS
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