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ash analysis or silica in my ash

updated thu 8 apr 99


Olivia T Cavy on thu 1 apr 99

Hello all,

I now know the silica content of my (screened) fireplace ash, which came
primarily from Colorado spruce with a very small amount of scrub oak. The
Alfred Analytical Laboratory told me that I have 99800.0 MG/KG or about
10% silicon (Si) in my ash, but silicon is usually thought of in terms of
silica (SiO2) in most naturally occurring substances. As Silica the
amount present is 213,600 mg/kg (PPM) and thus turns out to be 21%.

When tax season is over I'll see how I can use this information in
formulating cone 6 glazes from MY ASH.

If anyone in this group wants to comment and start me off in the right
direction, help would certainly be appreciated!


Bonnie D. Hellman
Pittsburgh, PA
work email: or
home email:

>>I just spoke with Dr. Roland Hale, the director of the Alfred
>>Laboratory, about getting a silica analysis of my 30 gallon sample of
>>fireplace ash (which is mostly spruce). He suggested making sure I
>>representative sample, by taking equal quantities from the top, the
>>middle and bottom of my trash can. Then he said to put 1/2 to a cup
>>1 quart plastic bag. So it can be mailed flat he suggested using a 1
>>quart size bag. (My sample has already been sieved through a window
>>screen, and is already quite well mixed.) The cost is $10 (include a
>>check payable to Alfred Analytical Laboratory) to analyze it for the
>>I know that someone else was asking about this recently, and wanted
>>share this information. BTW Dr. Hale was a delightful person to speak
>>with, and he mentioned that he is still looking for glazes to
>>have your glaze tested, he prefers a container that holds at least a
>>because they like to fill it with their testing liquids. They are
>>planning to publish a paper with the results.
>>Send your samples to:
>>Dr. Roland Hale
>>Alfred Analytical Laboratory
>>4964 Kenyon Road
>>Alfred Station, NY 14803
>>607-478-8074 or fax at 607-478-5324
>>Bonnie D. Hellman
>>Pittsburgh, PA
>>work email: or
>>home email:
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Trabka on fri 2 apr 99


"Ash Glazes" by Robert Tichane provides in depth insight into the
analysis of ash for glazes. The analysis covers many different ashes
from oak to spruce to straw to rice. The book is not difficult to read
and it provides insight into how to formulate and apply glazes so that
they have the "look and feel" of a traditional ash glaze.

The Si content of "pure" wood ash should be in the 1% to 7% range.
However if the raw material had imbedded dirt (i.e., sand) the Si
content could be much higher.


Craig Martell on wed 7 apr 99

Hello Bonnie:

For what it's worth, I'll tell you where I'd probably start to make cone 6
ash glazes. Well, I actually did some this past summer when I broke my
wrist and couldn't make any pots fer a bit.

Most ash magnates would probably tell you that ash isn't very active at cone
6. It doesn't melt much. So, fire some to cone 6 and see what happens.
Next, you can do some line blends with other fluxes such as: potash
feldspar, soda spar, nepeline syenite, some sort of ghastly boron product,
or boron frit, other frits etc. Once you find a good melt point, you can
start line blending in other oxides to this correct ratio of ash and another
flux. I use the term correct here to denote a visual acceptance of what's
going on with your tests. In other words, you see one you like and say,
"that looks damn good, I'll take it!"

I did some triaxial blends this summer with Jasper slip, cadycal 100, and
wood ash. I got some nice runny ash glazes that look similar to cone 10 ash
glazes. The Jasper slip contributed iron to the brew, so they were earthy
browns to beige colors. Cadycal 100 is a raw boron material that is very
similar to colemanite. You could use a boron frit, or gerstley borate if
you don't have access to cadycal. Jasper is available commercially and you
can use other slip clays as well. Alberta might be nice. Other cone 6
range fluxes that you might try are: zinc ox, talc, lithium carb, low melt
spodumene. Be careful with the lithium stuff which includes spod because of
the low expansion factor. One way to approach lithium is to use it with a
high expansion flux to balance the expansion, such as nepheline syenite or
soda spar. Neph sy melts very well at cone 6.

Apply some coloring oxides to your test tiles to see what kind of response
you are getting. Once you find a good melt and blend of fluxes with good
color, start introducing alumina and silica to make a hard glaze. Ian
Curries receipe method works very well for this. The deal is, you do a
biaxial blend of alumina and silica with the pure flux blend and get several
very good glazes in all ranges of suitability. Lemme know if you want more
info on how to do the Ian C stuff.

Once you have some finished glazes, you can put them into the seger formula
and then adjust where necessary. By this time you'll be ready for a condo
in Sun City and a couple of rounds of golf and a martini.

Now it's time for the glaze gurus to start typing. Lemme know if I can add
to the above When they are finished! I hope you noticed that I didn't call
you Olivia!!

later, Craig Martell in Oregon