Tim See on sun 24 feb 08
We are getting plans ready for the firing this summer. We will be doing our 6th firing April/May. I
have a question about ash.
Does the temperature at which ash is made greatly differ the contents of the ash?
reason why I am asking is a little observations made adding up. Our first firing had a very long
time at a middle temp like 1200 f for nearly 24 hours. from that firing we got runny drippy green
ash from lots of kinds of wood. the second firing we got to temp in 18 hours and the ask on the
work was corse and dark. again lots of kinds of wood. well from both firings I saved some of the
ash from inside. I also collected some from the Wegmans bakery department which is all
hardwood.
I was going to wash the ash and had them in separate buckets the ash from the 1st firing acted
how i would have guessed. the water became very caustic and had that smell. the other two the
one from the 2nd firing and the one from wegmans did not become as caustic and no smell. other
observations after were the color of the ash before and after. the first firing was lighter and softer.
the other two were dark and gritty.
So my guess would be that the ash that collects early in the firing when the kiln is still cool or relatively cool contains more fluxes of soda while temp increases the soda vaporizes in the burning and leaves the ash without the soda to melt it.
Does anyone have experience with holding their kiln at different temps to collect certain qualities
of ash? Or does the atmosphere in which the ash is produced effect the ash. Does the possible
buring off of the soda from the ash contribute in other ways ie. flashing flame paths and the shine
where ash hasn't collected? Any insight and idea would be super.. thanks
Tim See
Tony Ferguson on tue 26 feb 08
Tim,
I will try to answer your questions.
I also save ash from firing to firing. The type of wood, where it was grown, and what was in the soil will greatly affect what color it is when it melts. Mixing ash types makes any chance of figuring out what you are trying to figure out nearly impossible--at least for some of your questions.
How long you fire will affect everything in the kiln and on the pots and what's left in the fire pit. If you hold your kiln it allows ash to build it up. If you hold your kiln at melting temperature, all that ash that has built up will flux with your claybody and melt. The longer the hold, the more the ash melts the more everything is burned and used. Keep in mind, the quality of the ash as it layers in your fire pits is different from bottom to top and any soil, rocks, organic material makes its way to the bottom in concentrate. I never use the bottom inch of ash in my kiln as that is where the most "junk" is. And although careful with how I stack and where I put the wood before it goes into the kiln, there is always soil and other materials in the bark grooves that makes its way into your kiln and possibly onto your pots. I don't usually worry about it, I just keep things as clean as possible and make sure to hold at cone 10 for 4 to 6 hours or longer and let heat
work melt everything.
How you cool your kiln will also affect what colors you get, if the ash that has melted is transparent or opaque. It's a matter of personal aesthetics I suppose.
Now, like yourself, I have theorized about the quality of ash as to the length of the firing. When you mix wood types you are adding a plethora of variables to your equation as noted above, the type and where it was grown will affect how much soda and alkalies are in the wood. The quicker the firing, the more likely the least amount of melted ash and the more left over soda, alkalies, etc. The longer the firing, you are going to melt a lot of soluble alkalies, sodas, salts, etc. present in the wood. But, I never worry about that. The firing is the firing and the ash and what is left over is what it is. I never wash my ash because you wash out all the good stuff when you do. I do, however, now sieve my ash because I am not fond of clinkers growing on the outsides of my pots if I shake and bake or make an ash glaze. Hope this helps.
Tony Ferguson
Tim See wrote: We are getting plans ready for the firing this summer. We will be doing our 6th firing April/May. I
have a question about ash.
Does the temperature at which ash is made greatly differ the contents of the ash?
reason why I am asking is a little observations made adding up. Our first firing had a very long
time at a middle temp like 1200 f for nearly 24 hours. from that firing we got runny drippy green
ash from lots of kinds of wood. the second firing we got to temp in 18 hours and the ask on the
work was corse and dark. again lots of kinds of wood. well from both firings I saved some of the
ash from inside. I also collected some from the Wegmans bakery department which is all
hardwood.
I was going to wash the ash and had them in separate buckets the ash from the 1st firing acted
how i would have guessed. the water became very caustic and had that smell. the other two the
one from the 2nd firing and the one from wegmans did not become as caustic and no smell. other
observations after were the color of the ash before and after. the first firing was lighter and softer.
the other two were dark and gritty.
So my guess would be that the ash that collects early in the firing when the kiln is still cool or relatively cool contains more fluxes of soda while temp increases the soda vaporizes in the burning and leaves the ash without the soda to melt it.
Does anyone have experience with holding their kiln at different temps to collect certain qualities
of ash? Or does the atmosphere in which the ash is produced effect the ash. Does the possible
buring off of the soda from the ash contribute in other ways ie. flashing flame paths and the shine
where ash hasn't collected? Any insight and idea would be super.. thanks
Tim See
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Tony Ferguson
315 N. Lake Ave. Apt 312
Duluth, MN 55806
...where the sky meets the lake...
Artist, Educator, Photographer, Film Maker, Web Meister
fergyart@yahoo.com
(218) 727-6339
http://www.tonyferguson.net
---------------------------------
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Tim See on thu 28 feb 08
On Tue, 26 Feb 2008 13:04:15 -0800, Tony Ferguson wrote:
Tony,
Thanks for the help. I do collect wood ash for glazes but my bigger concern is ash development
on the work in the kiln from the firing. I understand holding it to melt and get more ash make the
firing longer. What I am really digging for is ash created at different temperatures different from
each other. for example we have good results from our firings but not SUPER and we have
speculated and changed some variables but we have been timid in making a large change to our
firing schedule. I speculate that holding at a lower temperature for a long period of time will
collect ash that contains more flux components. getting more melt out of the same amount of
ash. Not to mention a less active stoking pattern. In suggesting that temp could play a part in the
flux content of the ash I also wonder if atmosphere can also contribute to the characteristics of
the ash itself independent of the reduction effects on the clay. An example would be wood burns
in reduction, the ash from that wood contains more sodium because the sodium could not be volatilized in a reduction atmosphere, therefore stays in the ash ash lands on pot later on melts
and the subsequent fly ask glaze contains more sodium. This could be taken further to other volatiles that are present in wood ash.
There are list of elements and when they become volatile. But we are dealing with more variables
like atmosphere and how chemically attached they are, those numbers I would expect change
greatly. for instance iron in reduction compared to iron in oxidation.
In Another post I asked if there would be ways of testing the ash at different temperatures. would
a LOI test be beneficial? where or how are those done?
The more question I come up with the more question i come up with.
Thanks again Tony maybe you have some insight into this.
Tim
>
>I will try to answer your questions.
>I also save ash from firing to firing. The type of wood, where it was grown, and what was in the
soil will greatly affect what color it is when it melts. Mixing ash types makes any chance of
figuring out what you are trying to figure out nearly impossible--at least for some of your
questions.
>
>How long you fire will affect everything in the kiln and on the pots and what's left in the fire pit.
If you hold your kiln it allows ash to build it up. If you hold your kiln at melting temperature, all
that ash that has built up will flux with your claybody and melt. The longer the hold, the more the
ash melts the more everything is burned and used. Keep in mind, the quality of the ash as it
layers in your fire pits is different from bottom to top and any soil, rocks, organic material makes
its way to the bottom in concentrate. I never use the bottom inch of ash in my kiln as that is
where the most "junk" is. And although careful with how I stack and where I put the wood before
it goes into the kiln, there is always soil and other materials in the bark grooves that makes its
way into your kiln and possibly onto your pots. I don't usually worry about it, I just keep things as
clean as possible and make sure to hold at cone 10 for 4 to 6 hours or longer and let heat
> work melt everything.
>
>How you cool your kiln will also affect what colors you get, if the ash that has melted is
transparent or opaque. It's a matter of personal aesthetics I suppose.
>
>Now, like yourself, I have theorized about the quality of ash as to the length of the firing. When
you mix wood types you are adding a plethora of variables to your equation as noted above, the
type and where it was grown will affect how much soda and alkalies are in the wood. The quicker
the firing, the more likely the least amount of melted ash and the more left over soda, alkalies,
etc. The longer the firing, you are going to melt a lot of soluble alkalies, sodas, salts, etc. present
in the wood. But, I never worry about that. The firing is the firing and the ash and what is left over
is what it is. I never wash my ash because you wash out all the good stuff when you do. I do,
however, now sieve my ash because I am not fond of clinkers growing on the outsides of my pots
if I shake and bake or make an ash glaze. Hope this helps.
>
>Tony Ferguson
>
>
>Tim See wrote: We are getting plans ready for the firing this
summer. We will be doing our 6th firing April/May. I
>have a question about ash.
>Does the temperature at which ash is made greatly differ the contents of the ash?
>
>reason why I am asking is a little observations made adding up. Our first firing had a very long
>time at a middle temp like 1200 f for nearly 24 hours. from that firing we got runny drippy green
>ash from lots of kinds of wood. the second firing we got to temp in 18 hours and the ask on the
>work was corse and dark. again lots of kinds of wood. well from both firings I saved some of the
>ash from inside. I also collected some from the Wegmans bakery department which is all
>hardwood.
>
>I was going to wash the ash and had them in separate buckets the ash from the 1st firing acted
>how i would have guessed. the water became very caustic and had that smell. the other two the
>one from the 2nd firing and the one from wegmans did not become as caustic and no smell.
other
>observations after were the color of the ash before and after. the first firing was lighter and
softer.
>the other two were dark and gritty.
>
>So my guess would be that the ash that collects early in the firing when the kiln is still cool or
relatively cool contains more fluxes of soda while temp increases the soda vaporizes in the
burning and leaves the ash without the soda to melt it.
>
>Does anyone have experience with holding their kiln at different temps to collect certain
qualities
>of ash? Or does the atmosphere in which the ash is produced effect the ash. Does the possible
>buring off of the soda from the ash contribute in other ways ie. flashing flame paths and the
shine
>where ash hasn't collected? Any insight and idea would be super.. thanks
>Tim See
>
>______________________________________________________________________________
>Clayart members may send postings to: clayart@lsv.ceramics.org
>
>You may look at the archives for the list, post messages, change your
>subscription settings or unsubscribe/leave the list here: http://www.acers.org/cic/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
>
>
>
>
> Tony Ferguson
> 315 N. Lake Ave. Apt 312
> Duluth, MN 55806
>...where the sky meets the lake...
>
>Artist, Educator, Photographer, Film Maker, Web Meister
>fergyart@yahoo.com
>(218) 727-6339
> http://www.tonyferguson.net
>
>
>
>
>
>---------------------------------
>Never miss a thing. Make Yahoo your homepage.
>
>______________________________________________________________________________
>Clayart members may send postings to: clayart@lsv.ceramics.org
>
>You may look at the archives for the list, post messages, change your
>subscription settings or unsubscribe/leave the list here: http://www.acers.org/cic/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
gary navarre on thu 28 feb 08
Hay Tim, Folks,
I think I see what you are driving at...
--- Tim See wrote:
> On Tue, 26 Feb 2008 13:04:15 -0800, Tony Ferguson
> wrote:
>
> Tony,
> Thanks for the help. I do collect wood ash for
> glazes but my bigger concern is ash development
> on the work in the kiln from the firing. I
> understand holding it to melt and get more ash make
> the
> firing longer. What I am really digging for is ash
> created at different temperatures different from
> each other.
A while back we were looking at the Koie Ash Cooker
and the question came up relative to the temperature
the ash attained during burning having some
importance, firebox ash being so hot as to make
"clinkers" or the gritty stuff, and I tested the Koie
under fire and it got to around 550F +/- 100 degrees,
probably not over 700F in pockets, and no clinkers. I
don't recall if Koie washed the small amount he mixed
up for the workshop, a large bucket should take at
least 5 days, or always used it unwashed. This method
does collect most all the ash where as in a kiln a lot
settles on shelves and posts and exits the flue too.
for example we have good results from
> our firings but not SUPER and we have
> speculated and changed some variables but we have
> been timid in making a large change to our
> firing schedule. I speculate that holding at a lower
> temperature for a long period of time will
> collect ash that contains more flux components.
Maybe that is part of why Dick Lehman's pots have such
a dramatic effect, the volatile fluxes remain in the
ash long enough to contribute to the melt.
> getting more melt out of the same amount of
> ash. Not to mention a less active stoking pattern.
> In suggesting that temp could play a part in the
> flux content of the ash I also wonder if atmosphere
> can also contribute to the characteristics of
> the ash itself independent of the reduction effects
> on the clay. An example would be wood burns
> in reduction, the ash from that wood contains more
> sodium because the sodium could not be volatilized
> in a reduction atmosphere, therefore stays in the
> ash ash lands on pot later on melts
> and the subsequent fly ask glaze contains more
> sodium. This could be taken further to other
> volatiles that are present in wood ash.
Seems like that is pretty fine tuning of what might be
happening inside the chamber and it makes sense to me,
however I did score below the statistical average for
guessing on the final in chemistry 101, but still
passed the course, so I'm no authority.
>
> There are list of elements and when they become
> volatile. But we are dealing with more variables
> like atmosphere and how chemically attached they
> are, those numbers I would expect change
> greatly. for instance iron in reduction compared to
> iron in oxidation.
>
> In Another post I asked if there would be ways of
> testing the ash at different temperatures. would
> a LOI test be beneficial? where or how are those
> done?
>
> The more question I come up with the more question i
> come up with.
> Thanks again Tony maybe you have some insight into
> this.
> Tim
I'm looking to make a long slow fire for a few days
at least before doing an all night'er to high temp and
hold a good while to get melt, if I ever get the kiln
built so stay in there eh!
Gary Navarre
Navarre Pottery
Navarre Enterprises
Norway, Michigan, USA
http://public.fotki.com/GindaUP/
http://www.youtube.com/GindaUP
____________________________________________________________________________________
Never miss a thing. Make Yahoo your home page.
http://www.yahoo.com/r/hs
Tony Ferguson on thu 28 feb 08
Tim,
Amount of ash made in firing = amount of soda, salt, minerals. You can not separate the two. If you take longer to get to temperature, holding earlier temps, etc., you are burning more wood which produces more ash which produces more soda, alkalies, etc. The higher and longer you are at the higher temperature zone you will melt more, not less, of the soda. From what you are saying, I suspect its your wood. I could not believe the difference in the wood I was using from one sawmill to the other. It was the same species of wood but where it was grown (also all within 50 mile radius) dramatically changed the results of quality of ash on my work. What's the in soil (the minerals and their amounts) that makes the wood is paramount. If you really want gnarly ash effects, hold your kiln at the lower temps and let that ash build up on everything. And yes, you are going to change the atmosphere dynamics if you are oxidizing or reducing--but you are doing both in wood kiln
nearly all the time and its the natural cycle of the wood burning.
Tony Ferguson
Tim See wrote: On Tue, 26 Feb 2008 13:04:15 -0800, Tony Ferguson wrote:
Tony,
Thanks for the help. I do collect wood ash for glazes but my bigger concern is ash development
on the work in the kiln from the firing. I understand holding it to melt and get more ash make the
firing longer. What I am really digging for is ash created at different temperatures different from
each other. for example we have good results from our firings but not SUPER and we have
speculated and changed some variables but we have been timid in making a large change to our
firing schedule. I speculate that holding at a lower temperature for a long period of time will
collect ash that contains more flux components. getting more melt out of the same amount of
ash. Not to mention a less active stoking pattern. In suggesting that temp could play a part in the
flux content of the ash I also wonder if atmosphere can also contribute to the characteristics of
the ash itself independent of the reduction effects on the clay. An example would be wood burns
in reduction, the ash from that wood contains more sodium because the sodium could not be volatilized in a reduction atmosphere, therefore stays in the ash ash lands on pot later on melts
and the subsequent fly ask glaze contains more sodium. This could be taken further to other volatiles that are present in wood ash.
There are list of elements and when they become volatile. But we are dealing with more variables
like atmosphere and how chemically attached they are, those numbers I would expect change
greatly. for instance iron in reduction compared to iron in oxidation.
In Another post I asked if there would be ways of testing the ash at different temperatures. would
a LOI test be beneficial? where or how are those done?
The more question I come up with the more question i come up with.
Thanks again Tony maybe you have some insight into this.
Tim
>
>I will try to answer your questions.
>I also save ash from firing to firing. The type of wood, where it was grown, and what was in the
soil will greatly affect what color it is when it melts. Mixing ash types makes any chance of
figuring out what you are trying to figure out nearly impossible--at least for some of your
questions.
>
>How long you fire will affect everything in the kiln and on the pots and what's left in the fire pit.
If you hold your kiln it allows ash to build it up. If you hold your kiln at melting temperature, all
that ash that has built up will flux with your claybody and melt. The longer the hold, the more the
ash melts the more everything is burned and used. Keep in mind, the quality of the ash as it
layers in your fire pits is different from bottom to top and any soil, rocks, organic material makes
its way to the bottom in concentrate. I never use the bottom inch of ash in my kiln as that is
where the most "junk" is. And although careful with how I stack and where I put the wood before
it goes into the kiln, there is always soil and other materials in the bark grooves that makes its
way into your kiln and possibly onto your pots. I don't usually worry about it, I just keep things as
clean as possible and make sure to hold at cone 10 for 4 to 6 hours or longer and let heat
> work melt everything.
>
>How you cool your kiln will also affect what colors you get, if the ash that has melted is
transparent or opaque. It's a matter of personal aesthetics I suppose.
>
>Now, like yourself, I have theorized about the quality of ash as to the length of the firing. When
you mix wood types you are adding a plethora of variables to your equation as noted above, the
type and where it was grown will affect how much soda and alkalies are in the wood. The quicker
the firing, the more likely the least amount of melted ash and the more left over soda, alkalies,
etc. The longer the firing, you are going to melt a lot of soluble alkalies, sodas, salts, etc. present
in the wood. But, I never worry about that. The firing is the firing and the ash and what is left over
is what it is. I never wash my ash because you wash out all the good stuff when you do. I do,
however, now sieve my ash because I am not fond of clinkers growing on the outsides of my pots
if I shake and bake or make an ash glaze. Hope this helps.
>
>Tony Ferguson
>
>
>Tim See wrote: We are getting plans ready for the firing this
summer. We will be doing our 6th firing April/May. I
>have a question about ash.
>Does the temperature at which ash is made greatly differ the contents of the ash?
>
>reason why I am asking is a little observations made adding up. Our first firing had a very long
>time at a middle temp like 1200 f for nearly 24 hours. from that firing we got runny drippy green
>ash from lots of kinds of wood. the second firing we got to temp in 18 hours and the ask on the
>work was corse and dark. again lots of kinds of wood. well from both firings I saved some of the
>ash from inside. I also collected some from the Wegmans bakery department which is all
>hardwood.
>
>I was going to wash the ash and had them in separate buckets the ash from the 1st firing acted
>how i would have guessed. the water became very caustic and had that smell. the other two the
>one from the 2nd firing and the one from wegmans did not become as caustic and no smell.
other
>observations after were the color of the ash before and after. the first firing was lighter and
softer.
>the other two were dark and gritty.
>
>So my guess would be that the ash that collects early in the firing when the kiln is still cool or
relatively cool contains more fluxes of soda while temp increases the soda vaporizes in the
burning and leaves the ash without the soda to melt it.
>
>Does anyone have experience with holding their kiln at different temps to collect certain
qualities
>of ash? Or does the atmosphere in which the ash is produced effect the ash. Does the possible
>buring off of the soda from the ash contribute in other ways ie. flashing flame paths and the
shine
>where ash hasn't collected? Any insight and idea would be super.. thanks
>Tim See
>
>______________________________________________________________________________
>Clayart members may send postings to: clayart@lsv.ceramics.org
>
>You may look at the archives for the list, post messages, change your
>subscription settings or unsubscribe/leave the list here: http://www.acers.org/cic/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
>
>
>
>
> Tony Ferguson
> 315 N. Lake Ave. Apt 312
> Duluth, MN 55806
>...where the sky meets the lake...
>
>Artist, Educator, Photographer, Film Maker, Web Meister
>fergyart@yahoo.com
>(218) 727-6339
> http://www.tonyferguson.net
>
>
>
>
>
>---------------------------------
>Never miss a thing. Make Yahoo your homepage.
>
>______________________________________________________________________________
>Clayart members may send postings to: clayart@lsv.ceramics.org
>
>You may look at the archives for the list, post messages, change your
>subscription settings or unsubscribe/leave the list here: http://www.acers.org/cic/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
______________________________________________________________________________
Clayart members may send postings to: clayart@lsv.ceramics.org
You may look at the archives for the list, post messages, change your
subscription settings or unsubscribe/leave the list here: http://www.acers.org/cic/clayart/
Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
Tony Ferguson
315 N. Lake Ave. Apt 312
Duluth, MN 55806
...where the sky meets the lake...
Artist, Educator, Photographer, Film Maker, Web Meister
fergyart@yahoo.com
(218) 727-6339
http://www.tonyferguson.net
---------------------------------
Never miss a thing. Make Yahoo your homepage.
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