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Colouring Porcelain


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#1 High Bridge Pottery

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Posted 24 May 2013 - 01:20 PM

What is the best way to colour porcelain black? My thoughts were just to try adding some black iron oxide to the slip.

Looking to make slip cast moulds for cups and saucers to be black on the outside and white on the inside.

#2 Stuart Altmann

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Posted 24 May 2013 - 01:55 PM

What is the best way to colour porcelain black? My thoughts were just to try adding some black iron oxide to the slip.

Looking to make slip cast moulds for cups and saucers to be black on the outside and white on the inside.



Reply by Stuart Altmann: Iron oxides can produce a surprising range of colors, depending just on firing temperature and kiln atmosphere during firing alone. That is because iron has five(?) oxides, each with its own color. For example, a common, simple iron glaze recipe from Penland--I'm on the road now and don't have the formula memorized--starts with Fe2O3 (common 'red rust' ) and gives either a dark tomato red or jet black. In cone 10-11 in electric oxidation firing, this gives a dark tomato red, with various amounts of irregular black splotches.

#3 Marcia Selsor

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Posted 24 May 2013 - 03:31 PM

I thought Chris would jump in here. This is her area of expertise
. I would recommend using Black mason Stain #6600.
But check the blogs on Chris's website.
http://ccpottery.com

Marcia

#4 bigDave

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Posted 24 May 2013 - 04:39 PM

What is the best way to colour porcelain black? .


Maganese Dioxide and iron ox, are cheaper and can give nice dark tones, but fluuuxxxx the clay so what ever you are currently using...

Test

I use 6% Mang-ox in buff ^5 slip, and drop 4 cones to accomodate the lower melt/flux , make a nice dark dark brown


That is a starting place perhaps

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#5 Marcia Selsor

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Posted 25 May 2013 - 10:19 AM

Manganese Dioxide is toxic ,penetrates the skin, fumes are bad as is ingestion.
I wouldn't use it in a clay body. If I use it in a glaze I don't have my hands in it. Dave Shaner thinks it is what effected his health. Hans Coper also. Cheap is not necessarily wise.
Marcia

#6 High Bridge Pottery

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Posted 26 May 2013 - 07:21 AM

Thanks for the tips, I do not have any manganese anyway so testing out a little iron oxide with some porcelain today. Will add some pictures once I have completed the test Posted Image

#7 Chris Campbell

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Posted 26 May 2013 - 01:39 PM

I thought Chris would jump in here. This is her area of expertise
. I would recommend using Black mason Stain #6600.
But check the blogs on Chris's website.
http://ccpottery.com

Marcia


You are right Marcia ... It's called 'best black' too ... It is very black at about 8%.

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#8 bigDave

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Posted 26 May 2013 - 04:19 PM



You are right Marcia ... It's called 'best black' too ... It is very black at about 8%.


Thats precious ...@ 94.55 usd for 5 pounds...

Id be right out of business.

Thanks for the concern ladies, good motives

And good luck testing, High Bridge Potter


Big D

#9 High Bridge Pottery

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Posted 15 June 2013 - 12:36 PM

Well after some testing here is the black that I have produced. Porcelain (unknown recipe) 2 parts to 1 part black iron oxide.

I found that the natural clay was a much deeper black than when I added a transparent glaze on top. I think that is partially because the transparent has a slight white tinge to it.

Anyway turns out it is near perfect for a saucer unglazed which is a bonus :D and my saucer glazing technique is a little rough at best. All turned out quite nice as I didn't want to try other colorants. I just trust iron oxide, maybe I am uninformed but it seems safe to me.

Posted Image


#10 OffCenter

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Posted 15 June 2013 - 02:42 PM

Well after some testing here is the black that I have produced. Porcelain (unknown recipe) 2 parts to 1 part black iron oxide.

I found that the natural clay was a much deeper black than when I added a transparent glaze on top. I think that is partially because the transparent has a slight white tinge to it.

Anyway turns out it is near perfect for a saucer unglazed which is a bonus Posted Image and my saucer glazing technique is a little rough at best. All turned out quite nice as I didn't want to try other colorants. I just trust iron oxide, maybe I am uninformed but it seems safe to me.

Posted Image


Usually the pictures inserted into posts are too big but this one is too small. That is a really interesting cup and saucer but the picture is too small for me to get a good look at it. Do you have other cup & saucers?

Jim
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#11 High Bridge Pottery

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Posted 16 June 2013 - 09:01 AM

Yes it is a little small, I will sort out a bigger one sometime this week. My co-worker who is a good photographer was not in the studio. I had to battle with his complicated camera which is why it ended up so little. I can sort out a better resolution sometime this week Posted Image

I could not get the camera to focus on the work unless I was 2 meters away, never been able to understand lenses, apertures and so on...

I should have designed and fired the 'final' idea soon so will post some more then and grab a few pictures of other tests.

#12 justanassembler

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Posted 16 June 2013 - 10:50 AM

Manganese Dioxide is toxic ,penetrates the skin, fumes are bad as is ingestion.
I wouldn't use it in a clay body. If I use it in a glaze I don't have my hands in it. Dave Shaner thinks it is what effected his health. Hans Coper also. Cheap is not necessarily wise.
Marcia


Marcia,
I think you are incorrect with regards to manganese penetrating skin, it has been explained to me that because of the particle size of MnO2 and the fact that it is not soluble it cannot be absorbed through skin. I do know that it can cause mild skin irritation in some people, perhaps this is what you were thinking?




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