Cone 6 Red Stoneware Recipe

[tinbucket]

I am looking to develop a red/orange clay body for cone 6. I will be using the clay for throwing functional work so I would like it to be vitreous (or low porosity) and have some degree of plasticity. I have read for earthenware that as you approach 0% porosity the iron is dissolved/fluxed and you lose the bright orange-red color, moving more toward red-brown. Is the same true for stoneware? I will be scouring the internet for recipes and begin testing materials that I think will be useful.  I have considered using a virteous stoneware recipe and coloring it with mason stains, imagine a clay with the color of terracotta and the tightness of porcelain. I think this would be very costly and unnecessary, but I will test it just to see the result.  Any information/thoughts on the subject will be greatly appreciated - thanks in advance. 

[liambesaw]

I use a yellow cone 6 stoneware called Klamath yellow and it fires a beautiful red at cone 04, but at cone 6 it's darn near black from the iron.  My kiln does usually end up with a bit of reduction which converts a bit of that iron to Fe₃O_4.

Mason stains sure sound expensive as a clay additive but would give you the ability to use porcelain as your body.

[glazenerd]

Tin:

Newman Red and Redart are the two primary clays used in red bodied stoneware: there are others. Newman (now a blended clay) is more tolerant of heat than Red Art is: it will retain color at higher cones. That said, all high iron clays turn increasingly darker as the cone fire climbs. You could formulate a body at cone 3-4, that would retain a color closer to what you are after. Formulated correctly, the absorption could be held to 3-4%. Potassium would be a better flux choice; sodium creates a fair amount of pin hole issues in stoneware. You would have to hit 2100F in order to achieve any kind of vitrification: appreciable amounts of glass does not begin to form until 2050F. I would also explore alternate flux choices; and you could cheat by using frits. Fritware creates psuedo vitrification because frit begins to melt around 1450-1475. The frit creates the glass content in the body, which in turns reduces absorption. Depends how far down the rabbit hole you care to go: I live down here, so no big deal for me.

Tom

[GEP]

Are you dead set on making your own clay? Or would you be interested in a commercially made clay? Years ago I used a clay called 308 Brooklyn Red made by Standard. It’s quite an intense red/orange at cone 6. 

https://www.clayworkssupplies.com/product/308-standard-brooklyn-red/

[tinbucket]

Nerd: Thank you for the considerations, I am very much willing to test any suggestions. I have considered frit but I am heard the firing range can be very narrow when used in a body and it can make the fired ware brittle. I will definitely give that a shot. I have heard the same about using redart in a stoneware body, something about the fluxes effecting the the overall body differently because it is an earthenware. Some sources of iron I have considered so far: Redart, Newman, Lizella, Laterite, and Yellow Banks. I will look into sources of potassium, I may not need additional flux if I am using earthenware to lower the vitrification temp of the body. 

GEP: Thank you for the suggestion, but I am in a ceramics program at a university that requires me to mix my own clay. Also I think it will be a valuable experience to design a clay body to meet my specifications. 

[glazenerd]

Tin:

then I would start at

30% Newman Red,  25% OM4, 25% silica and 20% mahavir feldspar,  Cone 6.

stay away from laterite and lizella. Both have chemistry that will cause some issues.

tom

note: this is a starting point. Increase Newman by 10% until you get a color you like. Adjust OM4, silica, and spar downward .

[glazenerd]

Frit by the way; operates on a simple premise:

at cone 04 up to 33%, and as the cone climbs! the additions decline. Cone 6 for instance 10-15%. Cone 10- 0%.

[tinbucket]

Thanks again, nerd. What about Lizella is problematic? I really like the coarse texture it gives a clay body

 

[Magnolia Mud Research]

On ‎9‎/‎8‎/‎2018 at 12:21 AM, tinbucket said:

I am looking to develop a red/orange clay body for cone 6. I will be using the clay for throwing functional work so I would like it to be vitreous (or low porosity) and have some degree of plasticity.

Here is a clipped quote from Mel Jacobson's Clayart post dated: Mar 29, 2018:

quote: 
[Clayart] cone6, mel6 recipe (open source)
...
this is the recipe i sent to vendors, clayart friends, and
i call it open source clay recipe...mel6

this recipe is the old mackenzie, minnesota clay 1965 or so.
it is still my favorite, and [ *****]  has used it for years.
Fire Clay 50 (can be pounds etc.
Goldart Clay 50
Ball Clay 25
Sand (silica) 25
Feldspar 12
Redart Clay 30
any oxide for color
like ochre, iron ox, or black ox
or, in comination

in theory, you can use any quality stoneware clay recipe
that fires to cone 10.

they are much the same....the sand in this recipe gives it a very
broad range for throwing and hand construction.

the redart makes for a smooth, very long and workable
throwing quality. if you need more glass maker...add silica about
8. this body is totally vitrified at cone 6. it has been tested.

:end quote 

photos of the electric kiln fired ware are the last two images on mel's clayart website: http://www.melpots.com/CLAYART.HTML  the clay body is exposed below the glaze line at the bottom of the mugs.  

 

LT

[glazenerd]

Tin:

mostly because potters try to doctor up lizella to get it to seal up at cone 6. Lizella has some percentage of chlorite minerals ( green cast.). The iron is lower than the more common clays such as red art and Newman. Greenstripe tends to bloat easier than most.

you are trying to customize a fired color: which can be done. You need to do samples at 30%, then 40%, and 50%. Once in you get into your color zone, the 5% increments. 35% etc.

tom

[neilestrick]

When I worked for A.R.T. Clay we had a body that was a beautiful red/orange/brown at cone 6, that used spodumene to develop the color. The downside is that the lithium reduced the shrinkage rate a lot so that most typical glazes did not work on it.

[tinbucket]

Thank you neil, that is something I never would have considered. Maybe I can add enough to get a color response without lowering the thermal expansion too much. 

 

 

[David Gary Wright]

Check this out: http://www.davidgarywright.com/Neuman_Clay.html