Black Porcelain

[L BURCH]

Any of you guys and gals have any ideas, and or recipes, on how to make
black porcelain (cone 10) ?

Thanks in Advance

leonard

[hambone]

Any particular reason cone 10? Obsidian doesn't happen at cone 10 but
lower...
H A M

[David McBeth]

David McBeth
Department of Visual and Theatre Arts
University of Tennessee at Martin
Martin, Tennessee 38238

731-881-7416

Thanks in Advance

leonard

I have been making black porcelain slip to decorate bowls and platters lately. I use cobalt-free black mason stain, I fot get the number. Why not mix that in to the claybody either by hand or in the pugger mill.

Dave

[Paul Herman]

Hello All,

I took a colored clay workshop once where we just wedged dry stains
into soft clay. It worked just fine.

With black clays, the trick is in getting it black without adding so
much metal oxide that you get bloating. Some of the black clay we
made up did bloat. If I were to do it again, I suppose a line blend
of clay and stain would help.

Best,

Paul Herman

Great Basin Pottery
Doyle, California US
http://greatbasinpottery.com

> <winmail.dat>
>

[rickma...@comcast.net]

The thought Black Porcelain made me smile.   I smiled because I am a dinosaur in this business and we learned and I still adhere to the definintion that porcelain is white - blue white.   So much for history.  ;-)

 

I agree with the statement that too much metal will cause the body to flux - leading to bloating and other bad things.

 

In the olden days there were things called body stains that were more refractory than glaze stains.

I would think if you either lower your firing temp (maybe not practical) or use a higher firing clay you might be ok with a black clay body.

 

If you want an optical black - one that absorbs all wavelenghts of visible light - you need iron, cobalt, chrome, manganese, and nickel in the mix.  I used to use Iron Chromate as part of the mix to make black glass.  I think I would start with a smooth stoneware and make the black claybody that way.   For a slip I would use porcelain.

 

Rick Mahaffey

Tacoma Community College

 

-------------- Original message --------------
From: Paul Herman <potte...@frontiernet.net>

>
> Hello All,
>
> I took a colored clay workshop once where we just wedged dry stains
> into soft clay. It worked just fine.
>
> With black clays, the trick is in getting it black without adding so
> much metal oxide that you get bloating. Some of the black clay we
> made up did bloat. If I were to do it again, I suppose a line blend
> of clay and stain would help.
>
> Best,
>
> Paul Herman
>
> Great Basin Pottery
> Doyle, California US
> http://greatbasinpottery.com
>
>
> On Dec 6, 2006, at 8:04 AM, David McBeth wrote:
>
> >
> >
> > David McBeth
> > Department of Visual and Theatre Arts

> & gt; University of Tennessee at Martin

[craig edwards]

Hello: I have used Ceramic Color & Cemical's,   1612-c black stain. CCC makes stains that are made to colour clay. I use 5% and it works well.You could do a line blend to see if a smaller % would work. I have a feeling that you could get by with less, but 5% works and doesn't do any bad bloating.
Make good pots!
~Craig

[L BURCH]

I reformulated and batched out the Hiratsu Spar supplied by Lee Love some time back.  It seems to work well in several of the cone 10 firings recently.  I was curious how it would look on a black porcelain body, as well as other shino type glazes.  I was looking for a quick fix by posting my request, I see now that I will have to take the bull by the horns and do a line blend on my porcelain that I am currently using.  I well probably use a combination of both iron and manganese.  Thanks to all that have generously offer their responses and suggestions.  Much appreciated.

[David McDonald]

Ham,

 

    I've been concerned about this thread since it started, and now it's time to speak up. The problem with adding metallic oxides to clay bodies for colorant is pretty basic: Risk to the potter. Manganese is highly toxic, and easily absorbed through the skin. I don't know of any way to make pots without a great deal of hand to clay contact. ANYONE READING THIS, please consider carefully the toxic materials you add to your clay, realizing that you will be physically in contact with it. Adding these materials to glaze or slip formulas is a different story; it's much easier to avoid contact with the skin.

 

    I don't mean to scare anyone off from the wonderful possibilities that can be explored in ceramics. If a person really wants to try something out, there's always a safe way to do it. The important thing is to be very consciously aware of the hazards.

 

    David McDonald

[Lee]

On 12/7/06, David McDonald <da...@limberlostpottery.com> wrote:

> I've been concerned about this thread since it started, and now it's
> time to speak up. The problem with adding metallic oxides to clay bodies for
> colorant is pretty basic: Risk to the potter. Manganese is highly toxic, and
> easily absorbed through the skin. I don't know of any way to make pots
> without a great deal of hand to clay contact.

A friend told me that the black clays here in Japan often go blue
under a glaze, because the black is helped with cobalt. I would
skip the manganese. Go with black mason stains or a combination of
cobalt, iron and copper.

--
Lee in Mashiko, Japan
http://potters.blogspot.com/
"Let the beauty we love be what we do." - Rumi

[Paul Herman]

David,

I think you are mistaken about easily absorbing manganese through the skin. The fumes from firing are the really dangerous stuff. Manganese in the kiln fumes is of molecular size, and easily absorbed by breathing.

Best,

Paul Herman

Great Basin Pottery

Doyle, California US

http://greatbasinpottery.com

[craig edwards]

Hmmmmmmmm...... Does anyone know if having manganese in a stain makes it inert, both in the clay stage and firing ie fumes?
David, thanks, for bringing up safety, it is always good to examine the safety issues. So often I will be doing things that twenty years later turned out to be not a good thing to do. It would be nice to help start folks out armed with some knowledge.
Make good pots,
~Craig

[Tim Lynch]

David:  thank you for this post.  When this thread started my first reaction was that black porcelain was an oxymoron.  As it grew I wondered about the safety issues involved with the metal oxides involved.  Since this list reaches both novices and experts I welcome the cautionary note.  Gloves and a proper respiratory filter are absolutely necessary in this endeavor.

Tim


--
Tim Lynch
The Clay Man
541 S. Kentucky.
East Wenatchee, WA 98802

[Mike]

I have heard this as well, but not from what you would call a definitive source. There is a clay here called Kuromikage that fires out at pure black and comes with various amounts/sizes of grog. It's a really beautiful clay and doesn't do nasty things at even cone 11 or 12. I asked the rep what made it black and he told me manganese. I said isn't that dangerous, he laughed and said no, just the fumes during firing, so vent well. While my first impression is to believe him, he is trying to sell clay, and I'd rather err on the side of safety. I've seen a lot of potters use this clay here, but that doesn't mean it's safe. I'd want to be sure before I started using it on a regular basis. A weakened rice ash glaze breaks a really beautifull hazy light blue over that black body.
Some odd ideas about health here sometimes, without basis in fact. I saw some bottled water the other day in the store. Something like $5 a liter. Couldn't believe the price. The selling point was that it was deep sea water, and was healthy because of it's vanadium content. Isn't vanadium toxic?
As for the Manganese, does Eduard have any info on this?

Mike

Mike
in Taku, Japan

karatsupots.blogspot.com
potteryofjapan.com