mel jacobson on mon 26 apr 10
i have used volcanic ash mixed with gertsley borate for years
in the high school room as a base glaze.
it was 60-40. made a nice cone 4-6 glaze.
zircopax for opacity.
in some catalogs it is listed as pumice.
a glaze of 90-10 would be cone 10-11.
reverse it, 80-20 and you have a raku glaze.
the thing was: ash came in a 60 lb bag, gertsley was 40 lb.
add a bag of each to a 50 gallon garbage can, add water and you
have a base glaze. it cost like 30 bucks for 40 gallons. add that up
with pint jars for 190 kids at 5 bucks a jar. it was how i could run
a program with that many kids, we made our own.
and we made all of our own hand tools, we had a band saw, belt sander and s=
crap
wood, a spool of trolling wire for cut off wires. bisque fired
knobs. every kid
had their own set of pottery making tools, cut up an old foam mattress and
you have sponge...just soak the pieces overnight in a bucket with vinegar.
(clean as can be.) big pieces for clean up. small pieces to tape to a stic=
k.
everything was custom made.
mel
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html
new book: http://www.21stcenturykilns.com
John Rodgers on mon 26 apr 10
Mel........WOW!
Thanks for putting up that tip.
I have for years been hoarding a couple of 5 gallon buckets of volcanic
ash from Mt. Redoubt (many have heard of it) and Mt. Spur (not so many
have heard of it) - both across Cook Inlet from Kenai and Anchorage in
Alaska - and I figured one day - maybe - I would get around to using the
stuff. I collected it up long ago - way before I ever got to this stage
in my clay work. I really had no idea where to begin, but begin I would
at some point. Now you have given me a starting point and incentive.
This is gonna be fun.
John
John Rodgers
Clayartist and Moldmaker
88'GL VW Bus Driver
Chelsea, AL
Http://www.moldhaus.com
On 4/26/2010 6:48 AM, mel jacobson wrote:
> i have used volcanic ash mixed with gertsley borate for years
> in the high school room as a base glaze.
>
> it was 60-40. made a nice cone 4-6 glaze.
> zircopax for opacity.
>
> in some catalogs it is listed as pumice.
> a glaze of 90-10 would be cone 10-11.
>
> reverse it, 80-20 and you have a raku glaze.
>
> the thing was: ash came in a 60 lb bag, gertsley was 40 lb.
> add a bag of each to a 50 gallon garbage can, add water and you
> have a base glaze. it cost like 30 bucks for 40 gallons. add that up
> with pint jars for 190 kids at 5 bucks a jar. it was how i could run
> a program with that many kids, we made our own.
>
> and we made all of our own hand tools, we had a band saw, belt sander
> and scrap
> wood, a spool of trolling wire for cut off wires. bisque fired
> knobs. every kid
> had their own set of pottery making tools, cut up an old foam mattress
> and
> you have sponge...just soak the pieces overnight in a bucket with
> vinegar.
> (clean as can be.) big pieces for clean up. small pieces to tape to a
> stick.
> everything was custom made.
> mel
> from: minnetonka, mn
> website: http://www.visi.com/~melpots/
> clayart link: http://www.visi.com/~melpots/clayart.html
> new book: http://www.21stcenturykilns.com
>
>
Roxanne Hunnicutt on mon 26 apr 10
Re: volcanic ash as glaze
I USED Mt. St. Helen's ash straight at cone six. It was gawd awful glossy
but a glaze all by itself.
NOW where can I get this new ash? I saw a picture of a bunch of farmers
sweeping a roof off and I thought, put that in a box and send it to me!
Think anyone in Iceland is poor enough to want to share some?
MAYBE a potter there!?
Tell me if you know a way: IT IS TOO FUN! Like a xmas present: YOU Do not
know what you will get!
Rox in OR! I hear there are pretty clean deposits somewhere's around here
of mt. mazama's ash from way back when!
Paul Lewing on mon 26 apr 10
On Apr 26, 2010, at 8:43 AM, John Rodgers wrote:
I have for years been hoarding a couple of 5 gallon buckets of volcanic
ash from Mt. Redoubt (many have heard of it) and Mt. Spur (not so many
have heard of it) - both across Cook Inlet from Kenai and Anchorage in
Alaska - and I figured one day - maybe - I would get around to using the
stuff. I collected it up long ago - way before I ever got to this stage
in my clay work. I really had no idea where to begin,
I worked up a very nice glaze using Mt. St, Helens ash years ago. I
did it by getting an analysis of the ash and building a formula with
Insight. It was one of my first successes using glaze calculation
software and I hit it right on the first time, meaning the recipe I
designed melted to the surface characteristics I wanted and fit my
clay body.
Keep in mind that volcanic ash is not any one thing. It's the rock
spewed out by a particular volcano, so it is whatever rock happens to
be beneath that volcano. The ash that Mel was using was probably from
Kansas or somewhere in that area and was spewed out by the gigantic
volcano in New Mexico. The mountains around Ghost Ranch and Los
Alamos are the caldera from that volcano. It's a particularly fine
grain, consistent, and pure powder. Mt. St. Helens ash is not that
pure or that consistent, and since they are small (relatively) I doubt
that Mt. Redoubt or Mt. Spur ash is consistent either. meaning it will
vary considerably from location to location. The finest stuff settles
out last, so the closer to the mountain it was, the coarser it will
be. But you only have one sample of each, so this is not an issue for
you. And since the two mountains are from the same range, chances are
the chemistry is pretty similar.
The other characteristic of all volcanic ash is that it's powdered
rock, so it will settle to the bottom of the bucket really quickly.
MSH ash doesn't even give you time to pick your pot up and dip after
you've stirred it and it's back at the bottom of the bucket. That's
why Mel's choice of Gerstley Borate is the perfect addition to the
ash, because of its hydrological properties. We all know how GB turns
to jelly, and in this case that's a good thing. The glaze I designed
with MSH ash also uses lots of it. Addition of clay would also be a
good idea.
Materials like volcanic ash can be really valuable especially in
oxidation. It's so hard to get any kind of visual interest or texture
in oxidation glazes, and coarse materials like ash can really help. I
found MSH ash to be nice because it had speckles in it, and unlike the
speckles from ilmenite or granular manganese, they were varied in size
and color.
Paul Lewing
www.paullewingtile.com
www.paullewingart.com
David Hendley on mon 26 apr 10
Volcanic ash is wildly variable. I don't think there is anything
as "standard volcanic ash". It can be almost white, to black,
it can be a strong flux or refractory.
Mount St. Helen's ash from the '70's, for example, was very
dark in color and produced dark glazes. The Texas ash
I currently use is creamy yellow and makes a light brown
glaze and is prone to crawling.
It will interesting to see what kind of glazes the new
Eyjafjallaj=F6kull ash will make.
If you want to use ash as a glaze ingredient, glaze calculation
won't help you and the only way to find out what you have
is to mix up tests and line blends and fire them.
David Hendley
david@farmpots.com
http://www.farmpots.com
----- Original Message -----
>i have used volcanic ash mixed with gertsley borate for years
> in the high school room as a base glaze.
>
> it was 60-40. made a nice cone 4-6 glaze.
> zircopax for opacity.
>
> in some catalogs it is listed as pumice.
> a glaze of 90-10 would be cone 10-11.
>
Neon-Cat on mon 26 apr 10
I woke up thinking about putting some of my ancient Fort Worth
volcanic ash on a few more things so I was delighted to see Mel's post
bright and early today.
My local stuff when screened and used alone makes a lovely shiny green
glaze with stringers at cone 10 reduction. Golden to olive green in
oxidation. Takes colorants well.
The Kansas Geological Survey has a site (Kansas Volcanic Ash
Resources) where they tell of some work with their fall of the same
ash that once covered my area. They give some recipes and potter tips
for working with their local ash that might be of interest:
http://www.kgs.ku.edu/Publications/Bulletins/96/06_uses.html
Have fun John, it is fun (and easy)!
Marian
Neon-Cat
Paul Lewing on mon 26 apr 10
On Apr 26, 2010, at 9:33 AM, David Hendley wrote:
Mount St. Helen's ash from the '70's, for example, was very
dark in color and produced dark glazes.
It did in reduction. In oxidation it was a speckled grey green. And =3D20=
=3D
just in the interest of accuracy, it was May 18, 1981 and there is no =3D20=
=3D
apostrophe in Mt. St, Helens.
It will interesting to see what kind of glazes the new
Eyjafjallaj=3DF6kull ash will make. If you want to use ash as a glaze =3D20
ingredient, glaze calculation
won't help you and the only way to find out what you have
is to mix up tests and line blends and fire them.
It will if you can find an accurate analysis. I did for MSH ash. I'd =3D2=
0=3D
bet there will be analyses available for this ash before too long. I =3D20=
=3D
found (in Scientific American) analyses of ash from 10 different =3D20
locations for MSH ash, and an average. The chemistry varied slightly =3D20=
=3D
with distance from the source, mostly in higher iron levels closer to =3D20=
=3D
the mountain, but not enough that an average wouldn't have served just =3D2=
0=3D
as well.
Paul Lewing
www.paullewingtile.com
www.paullewingart.com
Elizabeth Priddy on mon 26 apr 10
That is my kind of glaze!=3D0A=3D0AIf I am making "my" work, I want complet=
e cl=3D
arity and control.=3D0A=3D0ABUT if I am going to just glaze it, I want it t=
o be=3D
an adventure.=3D0A=3D0AI have made simple ash glaze from a base of clear a=
nd a=3D
ddition of ash from the wood kiln. I have fired cone 6 up or down 4 cones.=
=3D
I like to see what stuff does when you heat it up. That is exciting, not=
=3D
knowing what is going to happen. I don't base my business or mortgage on =
=3D
this work, though, lest anyone think I lost my mind.=3D0A=3D0AI love volcan=
o st=3D
uff and so does my 5 year old. I would fire any ash and be pleased with wh=
=3D
atever comes out.=3D0A=3D0AGlaze calculation glazes may work better, but ta=
ke a=3D
ll the fun out of it, for me.=3D0A=3D0A=3D0A- ePriddy=3D0A=3D0AElizabeth Pr=
iddy=3D0ABea=3D
ufort, NC - USA=3D0A=3D0Ahttp://www.elizabethpriddy.com=3D0A=3D0A> It will =
interest=3D
ing to see what kind of glazes the new=3D0A> Eyjafjallaj=3DF6kull ash will =
make=3D
.=3D0A> =3D0A> If you want to use ash as a glaze ingredient, glaze=3D0A> ca=
lculat=3D
ion=3D0A> won't help you and the only way to find out what you have=3D0A> i=
s to=3D
mix up tests and line blends and fire them.=3D0A> =3D0A> David Hendley=3D0=
A> dav=3D
id@farmpots.com=3D0A> http://www.farmpots.com=3D0A>=3D0A=3D0A=3D0A
Eric Hansen on mon 26 apr 10
Folks: The volcanic ash available through your ceramics supplier is Mt. Etn=
a
ash. Its firing range is slightly different than Mt. St. Helens. Sheldon
Carey, former Prof. of Ceramics at KU wrote a Kansas Geological Bulletin on
Volcanic Ash deposit in Kansas - the book I think is still available. The
would be a much more sedimentary deposit - a long way from any volcano, it
would have been both wind - and water - bourne. Natural deposits of volcani=
c
ash are useful sources of glaze material where the occur. Try line blending
your local ash with a more fusible material to find your range. A number of
glaze recipes are in the archives they could be starting points as well.
Mel - your'e a great teacher - what a fantastic experience for those kids!
h a n s e n
On Mon, Apr 26, 2010 at 7:48 AM, mel jacobson wrote:
> i have used volcanic ash mixed with gertsley borate for years
> in the high school room as a base glaze.
>
> it was 60-40. made a nice cone 4-6 glaze.
> zircopax for opacity.
>
> in some catalogs it is listed as pumice.
> a glaze of 90-10 would be cone 10-11.
>
> reverse it, 80-20 and you have a raku glaze.
>
> the thing was: ash came in a 60 lb bag, gertsley was 40 lb.
> add a bag of each to a 50 gallon garbage can, add water and you
> have a base glaze. it cost like 30 bucks for 40 gallons. add that up
> with pint jars for 190 kids at 5 bucks a jar. it was how i could run
> a program with that many kids, we made our own.
>
> and we made all of our own hand tools, we had a band saw, belt sander and
> scrap
> wood, a spool of trolling wire for cut off wires. bisque fired
> knobs. every kid
> had their own set of pottery making tools, cut up an old foam mattress an=
d
> you have sponge...just soak the pieces overnight in a bucket with vinegar=
.
> (clean as can be.) big pieces for clean up. small pieces to tape to a
> stick.
> everything was custom made.
> mel
> from: minnetonka, mn
> website: http://www.visi.com/~melpots/
> clayart link: http://www.visi.com/~melpots/clayart.html
> new book: http://www.21stcenturykilns.com
>
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