CINDI ANDERSON on thu 29 nov 01
Often that is the iron from the clay showing through.
Cindi
Fremont, CA
GlassyClass wrote:
> I was wondering what clay body, or is it the glaze, that gives the dark
> brown or black specks in the glaze.
>
> Sincerely,
> Bud Britt
> Tustin, CA, USA
> glassyclass@worldnet.att.net
> http://www.homestead.com/glassyclass/
GlassyClass on thu 29 nov 01
I was wondering what clay body, or is it the glaze, that gives the dark
brown or black specks in the glaze.
Sincerely,
Bud Britt
Tustin, CA, USA
glassyclass@worldnet.att.net
http://www.homestead.com/glassyclass/
Dave Finkelnburg on fri 30 nov 01
Hi all!
At times somewhat coarse magnetite is used as an additive to clay. This
can causes a speckled appearance, depending on the glaze, and especially if
the clay is fired in reduction. The iron in the magnetite bleeds through
light-colored glazes and gives an "oatmeal" look.
You can get a similar effect by adding a small amount of magnetite
directly to a light-colored glaze. The problem is keeping the very dense
magnetite uniformly suspended during the glazing process! :-(
Rod's Bod from Laguna Clay is one body that contains heavy particles
high in iron which give such a speckled look in reduction firing.
Good glazing!
Dave Finkelnburg
>GlassyClass wrote:
>
>> I was wondering what clay body, or is it the glaze, that gives the dark
>> brown or black specks in the glaze.
Wade Blocker on fri 30 nov 01
Bud,
To get black or brown spots in a glaze just add 1% of granular
ilmenite,coarse manganese, iron filings, and if you are lucky enough to
have some black beach sand from Hawaii that will work also. Mia in sunny
ABQ
Jeff Lawrence on fri 30 nov 01
Hi,
In glazes I think you can use commercial color specks, granular anything --
ilmenite, manganese, rutile, rusted steel wool, key shavings (for
copper/tin/zinc). Some of these might not be bad in a clay body, too,
but the key shavings might color the language at the potters wheel
too strongly.
Thanks to whoever mentioned magnetite -- At cub scout camp one of the
activities in New Mexico is magnetite mining -- troll the arroyo sands
with a magnet and haul in magnetite galore.
I'm looking forward to trying some Hawaiian black sand in a clay body --
-- brought back a water bottle full and got the agriculturual quarantine
officers really excited until they realized it was just sand, which is
legal.
Jeff Lawrence
jml@cybermesa.com
Ron Roy on sat 1 dec 01
If the firing is in reduction and iron particles are resent like form
fireclay - it's the reduced (black iron) that fluxes through the glazes to
give the black specks.
If the firing is in oxidation it is probably granular manganese melting
through the glaze.
Adding granular manganese to a glaze can have the same effect and so can
granular rutile if the glaze is heavily fluxed although the specks are more
brown than black. The problem becomes - how to keep the granules suspended
while apply the glaze.
RR
>I was wondering what clay body, or is it the glaze, that gives the dark
>brown or black specks in the glaze.
>
>Sincerely,
>Bud Britt
>Tustin, CA, USA
>glassyclass@worldnet.att.net
> http://www.homestead.com/glassyclass/
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
Ababi on sun 2 dec 01
This is how I use the Manganese Dioxide.
To dry weight claybody I add no more than 0.3% as followed.
0.15% granular to about 24-40# 0.15% 60# I think it is a little too
much.
I recently purchased a 120# sieve to be able to wash away the powder. I
made it for health reason, but I thought it will help me to control the
background color.
I wight the clay add water, when it is soft I mix the claybody with a
jiffy mixer. when I have fine slurry I add the 0.3% manganese and dry.
This can be done shorter using recycled clay.
You can see it in my stoneware page.
..The manganese I bought from the nearest shop, clayart center.(in
Tacoma Wa.
Ababi Sharon
Kibbutz Shoval- Israel
Glaze addict
ababisha@shoval.org.il
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
http://www.israelceramics.org/
)
---------- Original Message ----------
>If the firing is in reduction and iron particles are resent like form
>fireclay - it's the reduced (black iron) that fluxes through the glazes
>to
>give the black specks.
>If the firing is in oxidation it is probably granular manganese melting
>through the glaze.
>Adding granular manganese to a glaze can have the same effect and so can
>granular rutile if the glaze is heavily fluxed although the specks are
>more
>brown than black. The problem becomes - how to keep the granules
>suspended
>while apply the glaze.
>RR
>>I was wondering what clay body, or is it the glaze, that gives the dark
>>brown or black specks in the glaze.
>>
>>Sincerely,
>>Bud Britt
>>Tustin, CA, USA
>>glassyclass@worldnet.att.net
>> http://www.homestead.com/glassyclass/
>Ron Roy
>RR# 4
>15084 Little Lake Rd..
>Brighton,
>Ontario, Canada
>KOK 1H0
>Residence 613-475-9544
>Studio 613-475-3715
>Fax 613-475-3513
>________________________________________________________________________
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