Replacing Talc with Nepheline Syenite in Cone 04 White Body

Share from (Lab Documentation and Calculation System) by Digitalfire.

See Also:
Cone 04 Terra Cotta Casting/Throwing Body, Transparent Glaze, Firing Schedule

Is this even possible? Yes. The body is as white or whiter, plasticity is the same, shrinkage and maturity also.

Project Name

Nepheline Syenite low temperature white body

Project Codenumber



This is a project to make a major change to our thinking about this type of body. Talc has always been the "accepted" way of making these bodies. Mixtures of ball clay and talc produce the outstanding working, casting, drying and firing properties that make this usable by hobbyists. Talc is the secret behind raising the thermal expansion to fit commercial cone 06-02 glazes. And the magic mix with ball clay creates fantastic plastic working properties (and casting). Until now, in North America, talc and ball clay grades could be selected to produce a very white burning body. Actually, that is not quite true, only ball clays could be selected. Only one talc was white enough: Texas talc.

However a major problem arose during February 2021: Texas talc, named C-98, is no longer available. Now we are faced with using talcs, that although are much whiter in the raw form, and on paper appear to be just as low in iron, in practice fire significantly darker. And they are not as effective at increasing body expansion as C-98. For a long time we have wanted to stop using talc, mainly because it makes powder handling and pugging of bodies so difficult. Now, the climate of litigation that surrounds it greatly increases our motivation to stop using it in these types of bodies. This is going to cause some pain, but it seems necessary.

Whiteness is very important. These bodies exist mainly because they are white. They are highly porous and have very poor strength in the fired state, but these properties are conveniently ignored in order to provide hobbyists and artware producers a white "canvas" on which to apply colorful glazes! That means the other talcs are "non-starters".

Our testing indicates that Nepheline Syenite, as a substitute, fires just as white. As you will note in the recipe-specific notes, nepheline has some really big advantages over talc, especially here in Canada. Of course, the main issue will be glaze fit. We will study that and develop base glazes as needed (low expansion frits make this possible and practical). We will be doing this work alongside both the L4410C white body and the L4170B terra cotta body (plus it's white engobe). We will document glaze and engobe fit across the entire range of cone 06-02 (and beyond for stoneware up to cone 2-4).

An exciting result of this work will be the ability of the L4410C body to improve the higher it is fired, all the way to cone 6, where it becomes an extremely dense porcelain!

More info and pictures coming soon.

Low Fire White Nepheline Syenite body

Code #


Owner: Joe Schmidt
Materials Amt
KT1-4 50.000 48.54%
Nepheline Syenite 50.000 48.54%
Additions Amt
Bentonite 3.000 2.91%



*L213 is a body made by Plainsman Clays, it has traditionally employed Texas talc and KT1-4 ball clay, a simple 50:50 mix. This is part of a project to explore the possibility that Nepheline Syenite could replace it.

We have been astounded by the results! It works physically in both the plastic form (this one) and the casting version (with 1% bentonite).

For firing, an issue is that at cone 04 this one may crazes commercial glazes that worked on the talc version. At cone 03 and 02 they fit better (we have two thermal expansion adjustable clear glazes, G1916Q and G3879, are testing variation on them to fit).

A huge advantage of this body recipe is that it fires more and more vitreous toward cone 6 and even beyond, achieving stoneware strength and density starting around cone 3 (whereas talc bodies degrade at higher temperatures). Amazingly the G1916Q works well at cone 2 and even above. And G2926B works well from cone 4-5 and up.

This body also has a lower thermal expansion than the talc version.



L4410C casting with 1% and 0.5% bentonite

With 0.5% bentonite many of the rim corners were breaking off during casting, demolding and dry finishing. Increasing to 1% completely solved the problem without increasing casting time too much.


SHAB - Shrinkage/Absorption

1 93.07 92.01 36.92 42.33 -6.0 6.9% 1.1% 14.7%
2 93.24 90.75 37.31 41.59 -4.3 6.8% 2.7% 11.5%
3 93.3 89.83 37.63 41.21 -2.5 6.7% 3.7% 9.5%
4 93.32 89.06 38.76 41.61 -2.0 6.7% 4.6% 7.4%
5 92.98 87.01 38.05 39.44 1.8 7.0% 6.4% 3.7%
6 93.01 86.32 37.67 38.46 3.0 7.0% 7.2% 2.1%
7 94.45 5.6%
8 94.31 5.7%
9 94.27 5.7%
10 94.12 5.9%
11 93.98 86.81 38.95 6.0 6.0% 7.6%
12 93.80 6.2%
13 93.88 6.1%

DFAC - Drying Factor

1 A000 LITE+

CLWC - Clay Water Content - Powder, Plastic

1 30.37 24.16 20.4%

LDW - LOI/Density/Water Content

1 17.34 14.02 19.1%

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Low Fire White Nepheline Syenite body" id="191679" key="15LbdhTh" date="2021-04-15" codenum="L4410C"> <recipelines> <recipeline material="KT1-4" amount="50.000" tolerance=""/> <recipeline material="Nepheline Syenite" amount="50.000" tolerance=""/> <recipeline material="Bentonite" amount="3.000" added="true"/> </recipelines> </recipe> </recipes>

Born: 2021-02-06, Modified: 2021-04-15 15:25:46
z=DrQLYpYP2o, id=191679, person_id=1624, group_id=58

Low Fire Nepheline body + Silica

Code #


Owner: Joe Schmidt
Materials Amt Units
KT #1-4 Ball Clay 12.000 50BG 47.21%
Nepheline Syenite A-270 12.000 50BG 47.21%
*Flint Silica #90 65.000 LB 5.11%
*N.S. 325 Bentonite 6.000 LB 0.47%

Total:576,525.60 (R)


*This is the same at L4410C, but adds 5% silica. We did this to see if it would improve glaze fit. That has not happened.

However we are firing test bars of this version across a wider range and have included it for this reason. We also tried many glazes at many temperatures. As a final mix it is not certain whether we will use this one or the L4410C recipe.


Antonio Hansen 2021-03-18


L4410G fired bars

L4410G, L4170B cone 2 spectrum low fire glazes

Spectrum low temperature 753 yellow, 754 orange glazes are bubbling at cone 2.

Cone 03 with Spectrum 753, 754 glazes

They are working well.

L4410G with G1916Q at cone 03

Looks good out of kiln

Cone 02 with Spectrum 753, 754 glazes

Some pitting is starting.


SHAB - Shrinkage/Absorption

1 93.35 87.88 38.09 40.26 1.0 6.7% 5.9% 5.7%
2 93.26 87.46 39.3 41.06 2.0 6.7% 6.2% 4.5%
3 93.34 86.13 38.75 38.96 5.0 6.7% 7.7% 0.5%
4 93.27 86.30 39.72 40.28 4.0 6.7% 7.5% 1.4%
5 93.3 85.85 39.46 40.63 3.0 6.7% 8.0% 3.0%
6 93.45 85.93 39.3 39.3 6.0 6.6% 8.0% 0.0%
7 93.57 86.42 39.79 39.78 7.0 6.4% 7.6% 0.0%
8 93.36 86.90 39.98 39.98 8.0 6.6% 6.9% 0.0%
9 93.32 92.61 40.22 46.37 -6.0 6.7% 0.8% 15.3%
10 93.13 91.12 39.08 44.08 -4.0 6.9% 2.2% 12.8%
11 93.34 90.35 39.63 44 -3.0 6.7% 3.2% 11.0%
12 92.71 88.81 41.55 45.37 -2.0 7.3% 4.2% 9.2%
13 92.67 87.75 41.97 45.12 -1.0 7.3% 5.3% 7.5%

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Low Fire Nepheline body + Silica" id="193048" key="ASf7FQq3" date="2021-03-27" codenum="L4410G"> <recipelines> <recipeline material="KT #1-4 Ball Clay " amount="12.000" tolerance="" unitabbr="50BG"/> <recipeline material="Nepheline Syenite A-270" amount="12.000" tolerance="" unitabbr="50BG"/> <recipeline material="Flint Silica #90" amount="65.000" tolerance="" unitabbr="LB"/> <recipeline material="N.S. 325 Bentonite" amount="6.000" tolerance="" unitabbr="LB"/> </recipelines> </recipe> </recipes>

Born: 2021-03-08, Modified: 2021-03-27 09:02:57
z=bhCRTnWtyw, id=193048, person_id=1624, group_id=58

Cone 05+ Expansion Adjustable Gloss Base

Code #


Materials Amt
Ferro Frit 3195 65.000 63.73%
Ferro Frit 3110 10.000 9.80%
Ferro Frit 3249 10.000 9.80%
No. 5 Ball Clay 15.000 14.71%
Additions Amt
Red Iron Oxide 2.000 1.96%


Auto Unity Formula + Analysis

CaO 0.56 8.21%
MgO 0.12 1.22%
K2O 0.01 0.35%
Na2O 0.31 5.13%
(KNaO) 0.33
TiO2 0.01 0.19%
B2O3 0.96 17.51%
Al2O3 0.50 13.48%
SiO2 3.19 50.44%
Fe2O3 0.05 1.98%


Si:Al: 6.3:1
SiB:Al: 8.3:1
R2O:RO: 0.3:0.7






0.08 per KG


*This recipe provides the greatest thermal expansion adjustability we have seen in a low fire clear glaze. It combines a middle-of-the-road thermal expansion frit with a very low and very high expansion frit (they cancel each other out but increase gloss of the otherwise silky Frit 3195).

This melts well from cone 05 and is stable to cone 2 or higher.

Do not assume the glaze fits because a piece emerges from the kiln without crazing or shivering. Thermally stress it (by two minute boiling-water and ice-water immersion cycles). We refer to this as the 65:10:10:15 recipe.
If this crazes, try 65:20:15 (3195:3249:EPK).
If it shivers, use 65:20:15 (3195:3110:EPK).

The ball clay also imparts good working properties and it has a lower LOI than EPK (to generate less micro-bubbles in the glaze).

The 2% iron oxide is only needed on dark burning bodies. It enhances the red color of terra cotta (when used as a transparent) and acts as a fining agent to remove the microbubbles they produce. If you are adding stains or using the glaze on a white burning body, remove the iron.

Although drop-and-soak firing schedule helps clarity of transparent glazes at higher temperatures this glaze will produce crystal clear results with fast firing.

We found about 3800 water for 4000 water to get 1.44SG. The slurry gels more than with EPK.


G1916Q at Cone 01 on 3D+iron

Very nice results on L3724E red body at cone 01. Piece is very strong.

1916J and Q fired to 1450F

These glazes are starting to melt, the surface having reached the consistency of a porcelain and have densitfied to very low porosity. Notice the iron in the ball clay really shows up at this stage (it will be less evident later).

G1916Q Cone 04 using 04DSSC schedule

Counterclockwise: L212, Raku, Buffstone, L213, L210, L215 Crazing out-of-the-kiln on Raku and buffstone. Bisque 04-03.

G1916Q and J fired 1650-2000F

Ten-gram balls melted and flattened as they fired. They soften over a wide range, starting well below cone 010! At 1650F carbon material is still visible (even though the glaze has lost 2% of its weight to this point), it is likely the source of the micro-bubbles that completely opacify the matrix even at 1950F (cone 04). This is an 85% fritted glaze, yet it still has carbon; think of what a raw glaze might have! Of course, this is a thick layer, so the bubbles are expected. But they still can be an issue on a piece of ware. So to get the most transparent possible result it is wise to fire tests to find the point where the glaze starts to soften (1450F in this case), then soak the kiln just below that (on the way up) to fire away as much of the carbon as possible.

Success with cyrstal clear glaze cone 03

Uses Cone 03 soak-soak-slow cool schedule. Left: P6282 with 3685U slip and 1916Q. Clear and very good. Glaze is thicker than the other two. Shivering on lip, the slip is not fitting the body. Center: P6282 with G2931F Ulexite clear. Better clarity even though it is applied very thin. Shivering on lip, the slip is not fitting the body. Right: L3724F with 3685U slip. No shivering. Very good coverage of the glaze, very clear, the best I have seen yet!

G1916Q on L215, L212, L210, L213, Buffstone at cone 03

All exited from the klin without crazing. The L215, L213, L210 and L212 samples subsequently survived a 300F/Icewater test without crazing, but the Buffstone did not. The L213 would not likely survive a cold-to-hot test without shivering.

1916Q cone 04, 03

Both were slow cooled. While the cone 04 version is glassy and ultra-gloss, it has significant clouding of micro-bubbles. The cone 03 version, right, is completely transparent.

G1916Q on L210 fired at cone 04

G1916Q+2%Iron on L212 talc body fired at cone 05

This will likely shiver over time. But the speckle that happens on white bodies is clearly visible.

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Cone 05+ Expansion Adjustable Gloss Base" id="56565" key="ozxZPiyi" date="2021-03-18" codenum="G1916Q"> <recipelines> <recipeline material="Ferro Frit 3195" amount="65.000" tolerance=""/> <recipeline material="Ferro Frit 3110" amount="10.000" tolerance=""/> <recipeline material="Ferro Frit 3249" amount="10.000" tolerance=""/> <recipeline material="No. 5 Ball Clay" amount="15.000" tolerance=""/> <recipeline material="Red Iron Oxide" amount="2.000" added="true"/> </recipelines> </recipe> </recipes>

Born: 2014-03-04, Modified: 2021-03-18 20:56:36
z=p2skpCaE1B, id=56565, person_id=10, group_id=58

Cone 06+ Low Expansion Transparent glaze

Code #


Materials Amt
Ferro Frit 3195 65.000
Ferro Frit 3249 20.000
No. 5 Ball Clay 15.000


Auto Unity Formula

CaO 0.54
MgO 0.23
Na2O 0.22
(KNaO) 0.22
B2O3 1.10
Al2O3 0.54
SiO2 3.04


Si:Al: 5.6:1
SiB:Al: 7.7:1
R2O:RO: 0.2:0.8






*This is a lower-thermal-expansion version of G1916Q (which was delay-crazing on the L4410 white cone 04 clay body (a mix of ball clay and nepheline syenite).

The original recipe was 65:10:10 of Frit 3195:3110:3249. This one trades all the high-expansion 3110 for low expansion 3249.

This is melting better and producing dazzling ultra clear results! One reason that it melts so well might be that the recipe contains no silica.

It even shivers on the L4170B, so the thermal expansion is certainly lower.

Equal parts of water/powder seem to create a pleasant slurry that does not settle. This is fitting the L4410C body on testing thus far.


XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Cone 06+ Low Expansion Transparent glaze" id="192370" key="gMKnCG7M" date="2021-04-15" codenum="G1916QL"> <recipelines> <recipeline material="Ferro Frit 3195" amount="65.000" tolerance=""/> <recipeline material="Ferro Frit 3249" amount="20.000" tolerance=""/> <recipeline material="No. 5 Ball Clay" amount="15.000" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2014-03-04, Modified: 2021-04-15 15:23:46
z=GN5sj9MXCr, id=192370, person_id=10, group_id=58

Cone 04 UltraClear Glossy Base

Code #


Materials Amt
Fusion Frit F-524 850.000 82.93%
Fusion Frit F-69 40.000 3.90%
EPK 90.000 8.78%
Silica 45.000 4.39%


Auto Unity Formula

BaO 0.04
CaO 0.44
MgO 0.05
K2O 0.10
Na2O 0.12
(KNaO) 0.21
SrO 0.25
B2O3 0.66
Al2O3 0.47
SiO2 3.91


Si:Al: 8.4:1
SiB:Al: 9.8:1
R2O:RO: 0.2:0.8






3.17 per KG


*I developed this for cone 04 to fit as many clay bodies (without crazing) as possible (my Zero3 clear works well on specific bodies but does not melt enough at cone 04 and its thermal expansion is too high to fit some bodies).

I found the inspiration for this on testing many commercial clears and finding one that stood above the others regarding fit and clarity at 04 (I had it analyzed and reverse engineered it using the materials I have). I have always been under the impression that low fire bodies have a wide enough range of thermal expansions that one glaze cannot be expected to fit them all. And that if a glaze melts well at cone 04 it will have too much melt fluidity past cone 02. But this glaze has made me question both, I am shocked at how it is possible that it can fit so many bodies and work across such a wide temperature range. So I had it analyzed at a lab and then created a recipe to source its chemistry. A stroke-of-luck was that a frit we already use to produce another glaze, Fusion Frit F-524, is close to the complete chemistry needed.

I have been surprised by other aspects of this recipe. It is crystal-clear on any body at any thickness (at cone 04 and above)! Additions of tin and zircon produce a white that melts just as well as the clear. It is amazing how the mobile the melt is, how it runs right off my fluidity checker! Yet it is not significantly more mobile at cone 1 than cone 04 (I glazed lots of pieces up to cone 2, it seems the higher the temperature the better this works!). And it has the amount of SiO2 and Al2O3 that a cone 6 glaze has! There is some kind of magic with this chemistry that I am anxious to learn more about.

While it hardens to a powdery surface, it is amazing how little gum solution is required to make it dry hard and hang on to the bisque when other layers are added on top.

If you want to make bright colored glazes this should be an excellent base (remember, this is the clear glaze recipe currently used by at least one commercial supplier of bright coloured glazes). Encapsulated stains are fantastic at low fire and they can be mixed to fine tune to color. If you are targeting a specific or exotic color then the ability to achieve it will be determined by your ability to source an exotic stain!

For the first mix I added 3000g of powder to 2400g of water to produce a specific gravity of 1.48SG. This produced a watery slurry. I added epsom salts to the point where further additions did not thicken the slurry (up to a total of 7g). This improved it considerably but it was still a little thin (although it covered and applied like a typical dipping glaze, drying in seconds on bisque ware). However the surface was too powdery so I removed 400g of water and replaced it with 400g gum solution. This slowed dip time to about a minute (waiting for the dripping to stop) but it now tolerates thick overlaying of Majolica colors (without them pulling it away from the bisque). For a single-coat dipping (where no overglaze work will be done) I would use about half the amount of gum solution.

I am continuing work on determining how to mix a good slurry of this recipe. It appears it may need to be gelled with VeeGum, that will also harden it and remove the need for the VeeGum.

This recipe also has implied adjustability (by increasing the low expansion Frit F-69 at the expense of Frit F-524).


Antonio Hansen 2019-05-13

Mike ODonnell and Fusion Frits says many customers use F280 and F38. He suggested F5 might be most similar to this. But I found that F524 was by far the closest.

Antonio Hansen 2021-03-07

If you want to make this into a air brushing glaze, which actually applies better to the sample board side discs, the glaze must be screened 200 mesh and then specific gravity adjusted to 1.40 and at this S.G. the powder to water ratio would be approx. 54% glaze powder and 46% water content.

Antonio Hansen 2021-03-07

Joe: Made some this glaze up in March of 2020 and checked June 2020 ( 3 months later), and glaze has hard panned quite badly, but was able to remix with a little effort. The next day it was easier to remix. The Specific Gravity was adjusted to 1.50 and a moisture content was taken at this point in time and found to be 54.25% glaze powder and 45.75% water content. This glaze was used on the low temperature sample boards for the L215 "bottom" side samples, as well as the L210 "top" side samples. The samples were bisqued in the cone 06-05 range and glaze fired at the same temperature more or less.


G3879 Clear glaze on Plainsman L211 - Cone 04

Glossy, crystal clear, no crazing! And this is a 42 mesh body containing zero talc.

Melt fluidity comparison with #1 commercial clear

We tested half-a-dozen commercial clears and found G3859 to be the best all-around one. This one has a very similar melt fluidity.

G3879 on Plainsman L210, L215 at cone 04

These are 42 mesh low fire bodies. They normally have issues with pinholing but using this glaze the results are stunning. The L210 contains no talc, the L215 has 10%, yet this glaze does not craze on either one (over time it shivers on the L215).

G3878 has a high surface tension

As can be seen in the way it has melted here.

G3879 on SIAL 25F, Plainsman J2, L4170 TerraCotta

These are very different bodies. The leftmost contains talc to raise the thermal expanison to help prevent crazing with commercial glazes. The center one contains nepheline syenite (for the same purpose). The terra cotta on the right is just Redart and ball clay. This glaze fits are all three! After a year, both the 25F and J2 were difficult to break, very strong!

Sial 10F, 25F with G3879 clear glaze at cone 03

Tile like these were done on a variety of bodies and fired at different temperatures. After a year: Sial 10F Cone 02: No crazing Cone 04: Moderate crazing over time Cone 06: Severe crazing Cone 03: No crazing Sial 25F Cone 1: No crazing Cone 03: No crazing Cone 04: Crazing badly L215 Cone 04: No crazing L210 Cone 04: No crazing L212 Cone 04: Crazing Cone 1: No crazing L213 Cone 04: No crazing

G3879 Clear on L4170 TerraCotta Casting

The clear glaze is G3879. The white on the outside of the one on the left has 10% added zircopax. The overglaze colors are Spectrum Majolica colors.

G3879 with 5% Tin Oxide on SIAL 10F

When mixing Tin (as an opacifer), it is very important to mix it well. The one on the left was mixed poorly (at high speed with my propeller mixer but not for long enough). The one on the right was mixed much better and so produces better opacity. Tin is expensive so this is important. This was not crazed after a year (cone 03).

G3879 on Plainsman Buffstone - cone 03

Buffstone is an entry-level low-price body not intended to fit commercial glazes. Yet this glaze fits at cone 03 (still fitting after a year)! And without any surface defects. At cone 04 it does craze over time.

G3879 Zircon White on SIAL 25F, 10F - cone 03

10% zircopax has been added. It is melting well so the percentage could be increased for great opacity on red burning bodies.

G3879 at cone 1 on SIAL 10F, 25F

Crystal clear, no running. Perfect!

GBMF test on G3879 at cone 1

It is not running and flowing nearly as much as expected. The melt surface tension holds it in place, so it should be able to fire to cone 2 and beyond.

G3879 on terra cotta at cone 04, 02, 1

This is on the L4170 body, it is a lighter firing product, 25F, from SIAL. After use on various bodies, it was clear that fit at cone 03 is better than at 04 and much better than 06.

G1916M, G3879, G2931K on L215 - Thick

Thickly applied encourage poor fit to show up. Clearly, as shivering and cracking demonstrate, G3879 is under excessive compressive on L215. The other two are not showing any issues (other than heavy bubbling because of the thickness). G1216M is a blend of 3124/3124 with kaolin. G2931K is the Zero3 clear.

L213 with G3879 glaze at cone 04

Survived 325F:IceWater test with almost no crazing. However there was a little shivering on the rim after a month. Another mug had no crazing on the inside after several months.

G3879 on L4115J2 buff body at cone 04

Glaze is ultra clear. It was refired at cone 022 to apply a decal. It was 325F to icewater tested without crazing. It was waterlogged (the bottom is bare clay) and then put in a microwave for two minutes. Despite getting incredibly hot it did not fracture or craze! Was still fitting after a year+.

G3879 on SIAL 10F at cone 02

No crazing after several months. Flawless service.


B - Tin White

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Cone 04 UltraClear Glossy Base" id="154451" key="gKbdawPR" date="2021-03-26" codenum="G3879"> <recipelines> <recipeline material="Fusion Frit F-524" amount="850.000" tolerance=""/> <recipeline material="Fusion Frit F-69" amount="40.000" tolerance=""/> <recipeline material="EPK" amount="90.000" tolerance=""/> <recipeline material="Silica" amount="45.000" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2019-04-15, Modified: 2021-03-26 10:50:09
z=ymC27QCiJ2, id=154451, person_id=10, group_id=58