Cone 10R speckles, rich red clay surfaces, bamboo glazes

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See Also:
Iron reduction body development

This showcases things cone 10R can do better than any other firing process. And it is the domain of potters only!


H440C (concentrate) #5

Code #

L4168G5

Materials Amt
Saint Rose Red 50.000
A2 Ball Clay 40.000
Custer Feldspar 10.000
Additions
Barium Carbonate 0.350

Total:100.35

Notes

*This is an effort to produce the reddest possible speckling reduction firing body that is still dense enough to be useful in making functional ware. The key to this is the high percentage of St. Rose Red (for color), the A2 for speckle and plasticity and the feldspar (which develops enough vitrification to neutralize the reduced iron and prevent black coring).

A little soft when throwing. But this is the best so far, pretty plastic. Not smooth but has tolerable tooth.

Pictures

G4168G5 mugs with Ravenscrag, G2571 glazes

These mugs were fired at cone 10R. The body is L4168G5 (50% Saint Rose Red, 40% A2, 10% Custer feldspar). The heavy iron specking is being sourced by both of these very unique clays. The left glaze is GR10-CW Ravenscrag Talc matte with added Zircopax. The right one has that same glaze on the inside and G2571A bamboo matte on the outside.
The G9 recipe ended up adding more A2 (thus less St Rose) and using Nepheline instead of Custer.

L4168G2 to G5 Cone 10R bars

These demonstrate varying proportions of St. Rose and A2 along with adjustments to the percentage of feldspar to study the impact on surface character and color. The G5 achieved the surface we want (but it used Custer Feldspar which is no longer available and was still a little short on plasticity). The G9 mix resolves both issues.

L4168G5 cone 9 fired bars

Typecodes

MAS-Master Ticket

Alternate Code Number:FIRERED

Testdata

SHAB - Shrinkage/Absorption

DLEN FLEN FWT BWT CONE DSHR FSHR ABS
992.9288.2641.9144.1910.07.1%5.0%5.4%
1292.8688.9941.7943.7210R7.1%4.2%4.6%
893.2188.9740.9543.988.06.8%4.5%7.4%
1092.597.4%

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="H440C (concentrate) #5" id="230587" key="WDSN7MXQ" date="2023-04-20" typecodes="MAS" codenum="L4168G5" picturebasename=""> <recipelines> <recipeline material="Saint Rose Red" amount="50.000" tolerance=""/> <recipeline material="A2 Ball Clay" amount="40.000" tolerance=""/> <recipeline material="Custer Feldspar" amount="10.000" tolerance=""/> <recipeline material="Barium Carbonate" amount="0.350" added="true"/> </recipelines> </recipe> </recipes>

Born: 1995-10-13, Modified: 2023-04-20 15:52:09

Ravenscrag Cone 10R Talc Matte White

RavenTalc White Matte

Code #

GR10-CW

Materials Amt
Ravenscrag Slip 35.000
Ravenscrag Slip 1000F Roast 52.000
Silverline 303 Talc 10.000
Additions
Zircopax 6.000

Total:103.00

Notes

*The Zircopax addition increases the gloss and the opacity of the GR10-C base recipe.

In our lab 1000 powder and 920 water produce a good consistency for use as a dipping glaze.

The 52:35 ratio is being used (rather than the normal 45:45) to minimize cracking during drying and compensate for the zero LOI of the roast material.

Pictures

Ravenscrag GR10 glaze variations

Left mug inside: G1947U clear
Left & right mugs outside: GR10-CW White
Right mug inside: GR10-A transparent (pure Ravenscrag Slip)
Clay body is H550.

G3952 Ravenscrag Talc Matte White on H440

GR10-CW white on outside of H550 mug

G1947U clear on the inside.

GR10-CW on H440 tests (dark and light)

Alternate Code Number:G3952

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Ravenscrag Cone 10R Talc Matte White" keywords="RavenTalc White Matte" id="224882" key="ftM2zH7W" date="2023-07-28" codenum="GR10-CW" picturebasename=""> <recipelines> <recipeline material="Ravenscrag Slip" amount="35.000" tolerance=""/> <recipeline material="Ravenscrag Slip 1000F Roast" amount="52.000" tolerance=""/> <recipeline material="Silverline 303 Talc" amount="10.000" tolerance=""/> <recipeline material="Zircopax" amount="6.000" added="true"/> </recipelines> </recipe> </recipes>

Born: 2004-09-15, Modified: 2023-07-28 11:06:10

G2571A Rutile Bamboo

Code #

L4028

Location

BD 840

P Materials Amt
Wollastonite 5.500
Custer Feldspar 28.500
EP Kaolin 28.000
Silica 15.000
Dolomite 19.000
Gerstley Borate 4.000
P Additions
* Ceramic Rutile 3.500
* Zircopax 10.000

Total:113.50

Auto Unity Formula

CaO 0.52
MgO 0.33
K2O 0.10
Na2O 0.05
(KNaO) 0.15
B2O3 0.05
Al2O3 0.47
SiO2 2.62

Ratios

Si:Al: 5.6:1
SiB:Al: 5.7:1
R2O:RO: 0.1:0.9

Expansion

6.7 (Molar:6.3)

LOI

14.5

Notes

*We transplanted the rutile and zircopax addition into this base after seeing it in another glaze recipe. This base produced a more velvety surface with less tendency to stain. This glaze is worth mixing in a large bucket, we use alot of it.

To mix a batch we use the following proportions:
Glaze powder: 51.3%
Water 48.7%
5000 grams will produce a specific gravity of about 1.5 and volume of 7 litres.

Pictures

G2571A L4028 bamboo on P6589 H550

L4028 bamboo on H550

L4028 vs. L4027 Bamboo

Both have the same rutile, zircopax addition.
The 4028 is based on G2571A, it is silkier. Likely more functional.
Body is H440.

L4028, 4027 bamboos very similar on H443

G2571A on H450 with L3954J black engobe

Fired at cone 10R. The black engobe has been applied inside and half way down the outsides.
Glaze on left is G2571A with 5% added rutile (Bamboo).
On the inside of the first mug is GR10-C Ravenscrag silky matte. The black engobe appears black under the clear glaze but brown under the bamboo glaze.

L4050B vase with G2571A bamboo

Typecodes

ST-Untitled typecode

Alternate Code Number:GS10-G

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="G2571A Rutile Bamboo" id="131711" key="QXtT9dFZ" date="2020-12-10" typecodes="ST" codenum="L4028" location="BD 840" picturebasename=""> <recipelines> <recipeline material="Wollastonite" amount="5.500" tolerance=""/> <recipeline material="Custer Feldspar" amount="28.500" tolerance=""/> <recipeline material="EP Kaolin" amount="28.000" tolerance=""/> <recipeline material="Silica" amount="15.000" tolerance=""/> <recipeline material="Dolomite" amount="19.000" tolerance=""/> <recipeline material="Gerstley Borate" amount="4.000" tolerance=""/> <recipeline material="Ceramic Rutile" amount="3.500" added="true"/> <recipeline material="Zircopax" amount="10.000" added="true"/> </recipelines> </recipe> </recipes>

Born: 2006-03-16, Modified: 2020-12-10 11:52:32

Cone 10R Silky Matte Bamboo 2

Code #

G2571B

P Materials Amt
Wollastonite 21.000
Custer Feldspar 32.000
EP Kaolin 20.000
Calcined Kaolin 9.000
Talc 14.000
Ferro Frit 3249 4.000
P Additions
* Rutile 3.500
* Zircopax 10.000

Total:113.50

Auto Unity Formula

CaO 0.52
MgO 0.34
K2O 0.10
Na2O 0.04
(KNaO) 0.14
B2O3 0.05
Al2O3 0.48
SiO2 2.66

Ratios

Si:Al: 5.5:1
SiB:Al: 5.6:1
R2O:RO: 0.1:0.9

Expansion

6.6 (Molar:6.2)

LOI

3.7

Notes

*This alters the G2571A base as follows:
-It sources CaO and MgO from wollastonite, talc and frit (instead of dolomite and talc). This change drops the LOI dramatically and eliminates even the silica from the recipe (the talc and wollastonite supply the SiO2)!
-This employs a combination of calcined and raw kaolin, that enables trading them one-for-another to fine-tune the slurry and drying properties.
-The frit 3249 sources B2O3 (enabling dropping the Gerstley Borate) and MgO (in a much more readily meltable form).

The fired result are visually the same as L4028 (the original bamboo base), but on close inspection that has a more silky and finer surface.

A darker color would be better, for the next test add a little iron oxide, 1 and 2%.

Pictures

G2571B Bamboo on H550, H443 Cone 10R

G2571B Bamboo on H550 mugs

L3954N engobe is under it on the left mug.

Untitled

Typecodes

ST-Untitled typecode

Alternate Code Number:GS10-G

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Cone 10R Silky Matte Bamboo 2" id="132632" key="1xDDFMwp" date="2022-11-18" typecodes="ST" codenum="G2571B" picturebasename=""> <recipelines> <recipeline material="Wollastonite" amount="21.000" tolerance=""/> <recipeline material="Custer Feldspar" amount="32.000" tolerance=""/> <recipeline material="EP Kaolin" amount="20.000" tolerance=""/> <recipeline material="Calcined Kaolin" amount="9.000" tolerance=""/> <recipeline material="Talc" amount="14.000" tolerance=""/> <recipeline material="Ferro Frit 3249" amount="4.000" tolerance=""/> <recipeline material="Rutile" amount="3.500" added="true"/> <recipeline material="Zircopax" amount="10.000" added="true"/> </recipelines> </recipe> </recipes>

Born: 2006-03-16, Modified: 2022-11-18 14:57:46