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GreyBird

Hudson River Clay

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Mary:

calcium bentonite is also abundant along the Hudson. Magnetite (iron) will present itself dark grey to black in sedimentary deposits. Plenty of mica and calcite around the Hudson as well. When I was candling some of the material, got that musty aroma of humus as well, albeit very low %. At this point, my prime suspects in your Hudson River clay.

arsenic is a normal by- product of natural oxidation/reduction of iron, especially magnetite. https://pubs.acs.org/doi/abs/10.1021/es702625e

Tom

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Both of these are 50% Hudson, 20% potash, 5% lithium, 20% silica. Added titanium to one of them. Did the job of melting, but the potassium created some pin hole issues. Will need a hold at peak. I took them out of the kiln at 350F, and plunked them into cold water- survived well enough.

image.jpg.e1db3a18338ba46e415f658524c9e05b.jpg

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Well, Here are my results... My conclusion being that I still need much adjusting. When I adjusted the Old Gold Albany Recipe to:

New Old Gold Albany:
Albany Slip - 75
Frit 3195 - 20
Alumina Hydrate - 5
Tin ox - 4

 

New Old Gold Hudson:
Hudson Clay - 75
Frit 3195 - 15
EPK - 15
Tin ox - 4


I got this (See Pic.) Did not shiver but the color is dreadful. I suppose I can work with it from here to try and lighten it and give it interest, but it has become very opaque and what I liked about the original was it was semi transparent and broke nicely over texture so I'll need to make some adjustments for sure. It is the glossy one on the left. The Old Gold Hudson is the same solid color but a matte version so I will make adjustments to that one as well and keep trying to come up with a glaze that I like.... more in line with the original recipes but that don't shiver of course. Maybe switching back to 12% Zircopax would be a good place to start :)

IMG-2877.jpg

Edited by GreyBird

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Well, Here are my results... My conclusion being that I still need much adjusting. When I adjusted the Old Gold Albany Recipe to:

New Old Gold Albany:
Albany Slip - 75
Frit 3195 - 20
Alumina Hydrate - 5
Tin ox - 4

I got this (See Pic.) Did not crawl but the color is dreadful. I suppose I can work with it from here to try and lighten it and give it 
interest, but it has become very opaque and what I liked about the original was it was semi transparent and broke nicely over texture so I'll need to make some adjustments for sure. It is the glossy one on the left. The Old Gold Hudson is the same solid color but a matte version so I will make adjustments to that one as well and keep trying to come up with a glaze that I like.... more in line with the original recipes but that don't shiver of course.

Edited by GreyBird
Trying to delete as it is a duplicate post

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On 9/16/2018 at 9:56 AM, glazenerd said:

Both of these are 50% Hudson, 20% potash, 5% lithium, 20% silica. Added titanium to one of them. Did the job of melting, but the potassium created some pin hole issues. Will need a hold at peak. I took them out of the kiln at 350F, and plunked them into cold water- survived well enough.

image.jpg.e1db3a18338ba46e415f658524c9e05b.jpg

Glazenerd, Why did you take out and plunge into cold water? Is that pat of the testing process? Maybe I'll also try some tiles with your recipe and add some Zircopax. As I read about Tin and Zircopax it seams they are opacifiers and I am not looking to make the glaze more opaque, but do they also act as Lighteners? Might they Lighten the color of the glaze? Oh and what clay body are these? Thanks!

Edited by GreyBird

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Also worth trying, Early on in this thread Magnolia Mud had suggested dropping the Lithium and seeing what happens or subbing Sodium or Potassium carbonate for it. The other two recipes I had tried were Bright Matte Albany andBright Mottled Albany. The bright Matte Albany came out fine albeit ugly, and the bright Mottled shivered so much the tile cracked into pieces. The major difference in the recipes is that the Bright Mottled had WAY more Lithium so I am also going to do a test with the original recipe and drop the Lithium and one where I sub it with Sodium or Potassium Carb. I've attached a pic of those tiles as well here:

IMG-2880.jpg

Edited by GreyBird

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Mary:

the hot dunk is just a preliminary test to check for crazing and in this case: shivering. There is a more formal test, but I do this as a "quick" check. In essence, checking stability. I mix all of my own clays: but in the pics above: a very clean white stoneware. Actually I have two shelves full of my early " learn to throw" pieces; good for testing or the landfill. This perticular clay/slip falls into the abyss in regards to glaze chemistry and/or clay chemistry. All I am doing at this point is stabilizing: as in no shivering, while maintains a full melt. Typically, a glaze has a maximum of 20% clay content! more often between 3-10%. So in dealing with 50-75% clay content, it gets interesting.

every clay variety you fire this on is going to change the color. < insert lengthy chemistry discussion here>. 

T

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On 9/18/2018 at 5:53 PM, GreyBird said:

Glazenerd, Why did you take out and plunge into cold water? Is that pat of the testing process? Maybe I'll also try some tiles with your recipe and add some Zircopax. As I read about Tin and Zircopax it seams they are opacifiers and I am not looking to make the glaze more opaque, but do they also act as Lighteners? Might they Lighten the color of the glaze? Oh and what clay body are these? Thanks!

I wondered why you added the tin. If you want a beige or tan, it or Zircopax might be a lightener in greater quantities, but don't waste the tin to lighten your iron red, Zirco is more economical. 

Iron reds like to be applied thinly. They also do look best on lighter clay (I think you discovered that with another test).

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1 hour ago, C.Banks said:

Try refiring your tests with lithium to an 06 bisque or there-abouts. You might be pleasantly surprised.

;)

C. Banks, what is the glaze used in your Avatar? :) It looks to be on a dark Stoneware... is it?

 

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local clay    43.48
silica    17.39
bone ash    8.70
spodumene    8.70
gerstley borate    8.70
black iron oxide    8.70
kona F-4 soda feldspar    4.35

The clay body is a buff stoneware - plainsman 450 iirc. The local clay we were digging resembled albany/alberta.

The original totaled 115. This was a very nice glaze in oxidation and liked a warm 9. When it was working well it showed red/orange with very little brown. It broke to black and behaved very well.

I sort of gave up on it for a bit but one day found some tidbit of inspiriation. I left it alone after that. I forget why the f4 is there - I left it in for luck.

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4 minutes ago, C.Banks said:

local clay    43.48
silica    17.39
bone ash    8.70
spodumene    8.70
gerstley borate    8.70
black iron oxide    8.70
kona F-4 soda feldspar    4.35

The clay body is a buff stoneware - plainsman 450 iirc. The local clay we were digging resembled albany/alberta.

The original totaled 115. This was a very nice glaze in oxidation and liked a warm 9. When it was working well it showed red/orange with very little brown. It broke to black and behaved very well.

I sort of gave up on it for a bit but one day found some tidbit of inspiriation. I left it alone after that. I forget why the f4 is there - I left it in for luck.

Thank You! I'll give it  whirl :)

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local clay     80

whiting     15

cobalt    2

rutile    4

This was another happy glaze. It worked first try.

I'd post a picture but I forget how i was resizing my photos. It fired to a not quite shiny, speckled black/gold. The cobalt showed a lot of character through a translucent titanium white.

I look at it now and think that 2% cobalt looks like a lot. Cobalt was a bit cheaper back then.

 

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7 minutes ago, C.Banks said:

local clay     80

whiting     15

cobalt    2

rutile    4

This was another happy glaze. It worked first try.

I'd post a picture but I forget how i was resizing my photos. It fired to a not quite shiny, speckled black/gold. The cobalt showed a lot of character through a translucent titanium white.

I look at it now and think that 2% cobalt looks like a lot. Cobalt was a bit cheaper back then.

 

 

Thank you so much!  If you are using a Mac just open in preview and go to "tools" then "adjust size" :) I will post results. I am firing to cone 6 so may need some adjustments.

Edited by GreyBird
additional info.

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On 9/21/2018 at 7:34 PM, C.Banks said:

local clay    43.48
silica    17.39
bone ash    8.70
spodumene    8.70
gerstley borate    8.70
black iron oxide    8.70
kona F-4 soda feldspar    4.35

The clay body is a buff stoneware - plainsman 450 iirc. The local clay we were digging resembled albany/alberta.

The original totaled 115. This was a very nice glaze in oxidation and liked a warm 9. When it was working well it showed red/orange with very little brown. It broke to black and behaved very well.

I sort of gave up on it for a bit but one day found some tidbit of inspiriation. I left it alone after that. I forget why the f4 is there - I left it in for luck.

C.Banks... Doing a quick search for Black Iron Oxide brought up Synthetic Black Iron Oxide... Nothing from my Ceramic shop. Not sure if it is the same thing. Do you know? Someone had posted a link of a good place for me to get ceramics materials but I'm looking though my posts and can't find it now. Don't you hate when that happens!

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My ceramics store has synthetic black iron oxide and magnetite.  They're chemically the same I suppose, but the synthetic has a finer particle size and is 99.9% pure whatever that means.  I know some friends who use granulated magnetite as a speckling agent in their clay bodies.  I use the synthetic for glazes and slips because it's super fine powder.

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7 hours ago, GreyBird said:

C.Banks... Doing a quick search for Black Iron Oxide brought up Synthetic Black Iron Oxide... Nothing from my Ceramic shop. Not sure if it is the same thing. Do you know? Someone had posted a link of a good place for me to get ceramics materials but I'm looking though my posts and can't find it now. Don't you hate when that happens!

Red iton oxide will work just fine. There is some high temperature science going on that changes red iron to black iron at some particular temperature or some such iirc.

I use black because it cleans up easier.

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I haven't read thru the whole thread so I may be repeating these references but here goes: http://www.nysm.nysed.gov/research-collections/geology/resources/hudson-river-lake-clay-exposures

http://www.clays.org/journal/archive/volume 1/1-1-19.pdf

http://www.co.dutchess.ny.us/CountyGov/Departments/Planning/nrichapthree.pdf   discussion of surface deposits starts on page 19

Don't know if it helps but may explain some of the sources for various elements. Its a thread of literature you can follow. 

 

 

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1 minute ago, terrim8 said:

I haven't read thru the whole thread so I may be repeating these references but here goes: http://www.nysm.nysed.gov/research-collections/geology/resources/hudson-river-lake-clay-exposures

http://www.clays.org/journal/archive/volume 1/1-1-19.pdf

http://www.co.dutchess.ny.us/CountyGov/Departments/Planning/nrichapthree.pdf   discussion of surface deposits starts on page 19

Don't know if it helps but may explain some of the sources for various elements. Its a thread of literature you can follow. 

 

 

Thanks, it's all helpful :)

 

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So here are some fun results… although most failed. Something is learned with each…

An ash Glaze from Glaze.org which I liked well enough and had only recently just tested (but didn’t come out anything like the glaze pictured) was just called Cone 6 electric Ash Glaze. The recipe was:
Wood Ash 54.56
Whiting 11.36
Ball Clay 11.36 (Subbed Hudson River Clay on the right tile)
Silica 11.36
Potash Feldspar 11.36
+
Copper Carb 03.00
Cobalt Carb 01.00

That is the tile on the left id the original recipe. The one on the left I subbed the ball clay for Hudson Clay :)

Ash.jpg

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