G2934 Cone 6 Matte Base Glaze and Variants

Share from Insight-live.com (Lab Documentation and Calculation System) by Digitalfire

Left column is the original G2934, a widely used matte (with dolomite). These variants source the MgO from talc and a frit, raise thermal expansion and smooth the surface, decrease crawling, add zinc, increase hardness.


Project Name

G2934Y Variations

Notes

All of these have the same chemistry as the original G2934. But they have different recipes of materials to source that chemistry.

These adjustments improve the application and firing performance in various ways. All of them are better than the original. They are also more expensive.

Don't forget that the degree of matteness is dependent on cooling rate. Faster cools are glossier (and more pleasant to the touch). If you cannot cool fast enough then blend in some glossy glaze (e.g. G2926B, G3806N).

Cone 6 Magnesia Matte Base

Code #

G2934

Materials Amt
Ferro Frit 3124 19.400 19.01%
EPK 18.300 17.93%
Dolomite 23.500 23.03%
Silica 26.960 26.42%
Calcined Kaolin 13.900 13.62%

Total:102.06

RO Unity Formula

CaO 0.54
MgO 0.39
Na2O 0.06
(KNaO) 0.06
B2O3 0.12
Al2O3 0.45
SiO2 2.71

Ratios

Si:Al: 6.0:1
SiB:Al: 6.2:1
R2O:RO: 0.1:0.9

Expansion

5.8

LOI

13.6

Cost

66.21 per kg

Notes

This matte recipe was developed at Plainsman Clays. It descends from a high-dolomite recipe that was originally used to compare shipments of dolomite for consistency.

WARNING: The degree-of-matteness is very dependent on cooling rate. Fast cooling (e.g. free-fall in a lightly-loaded or smaller kiln) produces a silky matte surface. Slower cooling (e.g. a heavily loaded kiln) produces a more matte and drier surface (subject to cutlery marking). Either adapt your firing curve or adapt this recipe to your firings (e.g. if not silky enough blend in some glossy G2926B, the mixing can be done by simply pouring together, volumetrically, the two slurries).

PlainsmanClays.com documents this recipe using a variety of stains.

Comments

2017-09-06

This is a slight variation of the Master recipe wherein the Frit 3124 has been increased, and the Flint Silica quantity is slightly higher.

G2934W has 4% tin oxide.

This is based on the 3728, a recipe that we use to compare new shipments of dolomite. However this raises the Al2O3 and SiO2 to the same levels as G2928C Ravenscrag matte.

URLs

Prepared public do..om Plainsman Clays

Pictures

G2934 with Hemlock Green, Pansy Purle Stains

10 gram balls have been melt down onto a tile at cone 6.
Top: G2934 with normal flow
Left: 8% 6213 Hemlock Green. Needs significant flux.
Right: 8% 6305 Violet stain. Flowing a little less, needs a little flux.

True mattes should still be matte if overfired

The G2934 is a high-MgO matte, it melts well and does not cutlery mark or stain easily. As evidence that it is a true matte, notice that it is still matte when fired to cone 7 or 8. VC71, while having a similar pleasant silky matte surface at cone 6, converts to a glossy if fired higher (suggesting that its cone 6 matteness is due to incomplete melting). For the same reason the VC71, it is whiter in color (but as soon as it begins to melt and have depth the color darkens).

G2934 + 5% Titanium thinner/thicker on M390

Typecodes

C6-Cone 6 Glazes

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Cone 6 Magnesia Matte Base" id="56852" key="hheZ5hKS" date="2019-03-20" typecodes="C6" codenum="G2934" picturebasename=""> <recipelines> <recipeline material="Ferro Frit 3124" amount="19.400"/> <recipeline material="EPK" amount="18.300"/> <recipeline material="Dolomite" amount="23.500"/> <recipeline material="Silica" amount="26.960"/> <recipeline material="Calcined Kaolin" amount="13.900"/> </recipelines> </recipe> </recipes>

Born: 2014-03-21, Modified: 2019-03-20 21:51:20

G2934 (lower-LOI)

Code #

G2934Y

Materials Amt
Ferro Frit 3249 10.000
Nepheline Syenite 10.500
Wollastonite 21.500
Talc 14.000
EPK 20.500
Silica 13.000
Calcined Kaolin 10.500

Total:100.00

Auto Unity Formula

CaO 0.54
MgO 0.40
K2O 0.02
Na2O 0.05
(KNaO) 0.06
B2O3 0.12
Al2O3 0.45
SiO2 2.73

Ratios

Si:Al: 6.1:1
SiB:Al: 6.4:1
R2O:RO: 0.1:0.9

Expansion

5.8

LOI

3.8

Cost

32.70 per kg

Notes

This is an "MgO matte". High MgO content is a common matting mechanism at cone 10 but also works at cone 6. This recipe has the same chemistry as G2934, however it sources the MgO from a frit and talc rather than from dolomite. The frit has a predictable chemistry, produces a much lower LOI (3.8 vs. 13.6), a smoother fired surface and better melt fluidity to host stains (stains look fantastic in this base).

WARNING: Like the original, the degree-of-matteness is very dependent on cooling rate. Fast cooling (e.g. free-fall in a lightly-loaded or smaller kiln) produces a silky matte surface. Slower cooling (e.g. a heavily loaded kiln) produces a matter and drier surface (subject to cutlery marking). Test in your circumstances to decide whether to adjust your firing to accommodate this or blend in some glossy G2926B produce the silky surface.

Fusion Frit F-69 can be used instead of Ferro Frit 3249 (actually, it is better). This recipe employs a mix of calcined and raw kaolin to keep the drying shrinkage down (to avoid cracking on drying). If you use pure kaolin it will likely crack during drying. If you do not have calcined kaolin just make your own (bisque fire a container of powder).

This glaze has a very low thermal expansion and will not craze an any common clay body. It accepts stains exceptionally well.

We recommend doing cutlery marking tests on your ware. If they mark, blend in a little transparent glossy glaze (like G2926B). This will compromise the matteness a little but will reduce the marking.

Again, although matte in appearance, this glaze has a high melt fluidity. That means that brush-on colors could bleed.

Because this contains both calcined and raw kaolins you can adjust their ratios to control the compromise between dry hardness and drying shrinkage. If better gelling response to Epsom salts (or other flocculant) is needed trade one or two percent raw kaolin for bentonite (to increase the particle surface area).

1100 water, 1000 powder to get creamy mix.
Regular 2934 (with dolomite) took more water, about 1300. Nicer surface than G2934, same matteness, better fluidity.

Joe: April 29/19 Mixed up a batch and added 10% Mason #6021 Red stain. Final totals were:
G2934Y + 10% stain weighed 5045 grams.
Water weighed 5450 grams.
Let glaze sit for 3 days to saturate before adding final water to bring to a S.G. of 1.43 and viscosity was approx. 12 seconds with ford cup.
At these quantities, the final ratios would be:
Glaze powder (including stain) 48%
Water 52%
This mixture yielded about 7.3 litres of mixed glaze. This glaze was screened 80 mesh and has no Epsom salts added.

Pictures

G2934Y plus 8% Cerdec orange stain on Polar Ice, P300

The stain is #239616 encapsulated. The silky surface is stunning. The color is brighter on whiter porcelains.

G2934Y vs. G2934 melt flow balls

10 gram balls were melted down onto these tiles at cone 5.5.
On darker clay bodies the glaze is translucent. For white on this type of clay body a zircopax addition would be needed.

G2934Y vs G2934 melt flow test

The difference is quite amazing. The chemistry is the same. But the MgO is much more readily released from its source materials in the Y version. Also, even thought the melt is more fluid, it is still just as matte. Part of the reason for the extra fluidity could be the much lower entrained micro-bubble population in the Y (these possibly impeding the flow of the dolomite version on the left).

G2934Y matte with Cerdec red, orange stains

8% stain in each. Cone 6. Drop and hold firing. The surface quality is truly stunning!

G2934Y matte on M370 - cup

Surface very pleasant and finer than the standard G2934.

G2934 (left) vs G2934Y (right) at cone 6

G2934Y with brushwork decoration - By Ingeborg Koot

It is not bleeding significantly because the glaze has not been applied too thick.

Typecodes

C6-Cone 6 Glazes

Variations

16 - Yellow

1680 dry and 1400 water produced SG of 1.44. Pretty thick, added a little darvan.

239616 - Orange

Cerdec stain. Required no Epsom salts at 1.43 SG. Joe: Aug.2/18 Made a batch of this glaze: Total Powder 3400 grams Total Water 4000 grams S.G via Viscometer 1.417 Viscosity via Ford Cup 12

4 - Overglaze Blue

Test this as a brush-on color for using over G2934Y. We should demonstrate to customers how to fine tune the melt fluidity of an overglaze color and how to mix it with gum to make it paintable.

6000 - Shell Pink

Joe: Aug.8/18 made a batch using same percentages as when I made a batch of the Orange version on Aug.2/18. Total Powder: 2500 grams Water: 2946 grams. S.G. vis Viscometer was 1.401 Viscosity Ford

6213 - Hemlock Green

A little dark. Very intense. Mixed 110 water to 100 dry (3575/3250) to get 1.43 SG.

6304 - Purple

6364 - Baby Blue

3380 powder, 2800 water. 1.43 SG. Worked perfectly.

6700 - White

Pink - Mason 6020

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="G2934 (lower-LOI)" id="113976" key="GktjEoKg" date="2019-10-22" typecodes="C6" codenum="G2934Y" picturebasename=""> <recipelines> <recipeline material="Ferro Frit 3249" amount="10.000"/> <recipeline material="Nepheline Syenite" amount="10.500"/> <recipeline material="Wollastonite" amount="21.500"/> <recipeline material="Talc" amount="14.000"/> <recipeline material="EPK" amount="20.500"/> <recipeline material="Silica" amount="13.000"/> <recipeline material="Calcined Kaolin" amount="10.500"/> </recipelines> </recipe> </recipes>

Born: 2014-03-21, Modified: 2019-10-22 13:52:07

G2934Y (Anti-Crawling)

Code #

G2934Y1

Materials Amt
Ferro Frit 3249 10.000 10.10%
Nepheline Syenite 10.500 10.61%
Wollastonite 21.500 21.72%
Talc 14.000 14.14%
EPK 15.000 15.15%
Silica 13.000 13.13%
Calcined Kaolin 15.000 15.15%
Additions Amt
CMC Gum 0.200 0.20%

Total:99.20

Auto Unity Formula

CaO 0.54
MgO 0.40
K2O 0.02
Na2O 0.05
(KNaO) 0.06
B2O3 0.12
Al2O3 0.45
SiO2 2.73

Ratios

Si:Al: 6.1:1
SiB:Al: 6.4:1
R2O:RO: 0.1:0.9

Expansion

5.7

LOI

3.0

Cost

32.98 per kg

Notes

This change reduces drying shrinkage and increases dry hardness (to prevent crawling). The calcined kaolin is supplying more of the Al2O3 and the raw kaolin less. The overall chemistry remains the same. The glaze will not dry as hard but will shrink less (but the gum will compensate for this).

Increase the gum to as high as can be tolerated (the higher the percentage used the slower the glaze will dry and the more dripping will occur, but it will dry harder and bond better with the bisque). Sufficient gum will completely eliminate cracking (and therefore crawling).

Pictures

Typecodes

C6-Cone 6 Glazes

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="G2934Y (Anti-Crawling)" id="156653" key="ijaC3epq" date="2019-07-27" typecodes="C6" codenum="G2934Y1" picturebasename=""> <recipelines> <recipeline material="Ferro Frit 3249" amount="10.000"/> <recipeline material="Nepheline Syenite" amount="10.500"/> <recipeline material="Wollastonite" amount="21.500"/> <recipeline material="Talc" amount="14.000"/> <recipeline material="EPK" amount="15.000"/> <recipeline material="Silica" amount="13.000"/> <recipeline material="Calcined Kaolin" amount="15.000"/> <recipeline material="CMC Gum" amount="0.200" added="true"/> </recipelines> </recipe> </recipes>

Born: 2014-03-21, Modified: 2019-07-27 23:51:56

G2934Y (Higher COE/Stony)

Code #

G2934Y2

Materials Amt
Fusion Frit F-69 7.500
Ferro Frit 3110 21.000
Wollastonite 15.000
Talc 14.500
EPK 20.000
Silica 7.000
Calcined Kaolin 15.000

Total:100.00

Auto Unity Formula

CaO 0.44
MgO 0.40
K2O 0.02
Na2O 0.15
(KNaO) 0.17
B2O3 0.12
Al2O3 0.45
SiO2 2.81

Ratios

Si:Al: 6.3:1
SiB:Al: 6.5:1
R2O:RO: 0.2:0.8

Expansion

6.3

LOI

3.7

Cost

17.69 per kg

Notes

The G2934 and G2934Y have very low thermal expansions. That is good to prevent crazing but it can cause shivering for some bodies. This version increases KNaO (sourcing it from Ferro Frit 3110) at the expense of CaO.

This change has the additional effect of making the matte surface physically smoother and more bone-like. It does cutlery mark somewhat, but is quite striking.

The Fusion Frit F-69 is the very similar chemistry as Ferro Frit 3249 (it is preferred since 3249 is maintained for the abrasives industry and the chemistry is not as consistent).

Pictures

Very smooth yet stony matte G2934Y2 Cone 6

Cutlery marks but almost cleanable. On M370.
Surface porcelain like, almost invisible on ware are first glance.

G2934Y2 matte on outside of polar ice piece

Typecodes

C6-Cone 6 Glazes

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="G2934Y (Higher COE/Stony)" id="143110" key="gL1Nrkem" date="2019-07-27" typecodes="C6" codenum="G2934Y2" picturebasename=""> <recipelines> <recipeline material="Fusion Frit F-69" amount="7.500"/> <recipeline material="Ferro Frit 3110" amount="21.000"/> <recipeline material="Wollastonite" amount="15.000"/> <recipeline material="Talc" amount="14.500"/> <recipeline material="EPK" amount="20.000"/> <recipeline material="Silica" amount="7.000"/> <recipeline material="Calcined Kaolin" amount="15.000"/> </recipelines> </recipe> </recipes>

Born: 2014-03-21, Modified: 2019-07-27 23:15:06

G2934 Super Durable

Code #

G2934Y3

Materials Amt
Nepheline Syenite 5.400 5.39%
Wollastonite 17.900 17.88%
Talc 17.900 17.88%
EPK 12.100 12.09%
Silica 25.300 25.27%
Calcined Alumina 10.600 10.59%
Ferro Frit 3134 10.900 10.89%

Total:100.10

Auto Unity Formula

CaO 0.53
MgO 0.39
Na2O 0.07
(KNaO) 0.07
B2O3 0.10
Al2O3 0.45
SiO2 2.72

Ratios

Si:Al: 6.1:1
SiB:Al: 6.3:1
R2O:RO: 0.1:0.9

Expansion

5.9

LOI

2.7

Cost

63.30 per kg

Notes

A customer, who makes floor tiles, wanted more durability so he did research finding that industrial tile technicians supply some of the Al2O3 from calcined alpha alumina to add durability to a glaze. The surface has stayed almost the same as G2934Y. And it still has the same chemistry as G2934.

We added 2g of VeeGum T per 1000g of dry glaze.

Pictures

G2934Y3/Y4 mix with 10% Mason 6600

More matte than usual, but very striking. Cutlery marks. Needs some glossy glaze added.

G2934H vs. G2934Y3 Melt Fluidity

Firing was not held at cone 6, but dropped and soaked at 2100F.

G2934Y3 on M340, M390, Coffee

Surface is smoother, very nice.
Well melted. Not cutlery marking.

Typecodes

C6-Cone 6 Glazes

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="G2934 Super Durable" id="155345" key="pBd1eFSJ" date="2019-09-27" typecodes="C6" codenum="G2934Y3" email="zeega.tomc@gmail.com" picturebasename=""> <recipelines> <recipeline material="Nepheline Syenite" amount="5.400"/> <recipeline material="Wollastonite" amount="17.900"/> <recipeline material="Talc" amount="17.900"/> <recipeline material="EPK" amount="12.100"/> <recipeline material="Silica" amount="25.300"/> <recipeline material="Calcined Alumina" amount="10.600"/> <recipeline material="Ferro Frit 3134" amount="10.900"/> </recipelines> </recipe> </recipes>

Born: 2014-03-21, Modified: 2019-09-27 16:15:17

G2934 Super Durable #2

Code #

G2934Y4

Materials Amt
Ferro Frit 3110 9.000
Wollastonite 21.000
Silverline Talc 14.000
Bentonite 2.000
Silica 23.000
Calcined Alumina 10.000
EPK 12.000
Ferro Frit 3249 9.000

Total:100.00

Auto Unity Formula

CaO 0.55
MgO 0.38
Na2O 0.06
(KNaO) 0.06
B2O3 0.11
Al2O3 0.45
SiO2 2.72

Ratios

Si:Al: 6.1:1
SiB:Al: 6.4:1
R2O:RO: 0.1:0.9

Expansion

5.8

LOI

2.7

Cost

57.85 per kg

Notes

This sources as much MgO from a frit as possible. It also incorporates bentonite to produce better response to Epsom salts. And sources KNaO from frit 3110 rather than Nepheline.

This still melts incredibly well for a glaze that only has 0.11 boron!

Pictures

G2934Y4 melt fluidity test

Not held at cone 6, but dropped 100F and held for 30 minutes. Compared to G2934 (which is not running as well as usual). This one, on the right, looks identical to Y3. That means the frit:talc combo is not really melting it any better than the talc alone did.

G2934Y4 on M370, M390 fired cone 6

Stunning silky matte surface of very fine texture.

G2934 (left) vs G2934Y4 on M370

They look almost the same. Cone 6. Slow cool firing.

G2934 (left) vs. G2934Y4

Cone 6 on M390, M340, Coffee Clay

G2934Y4 on a range of american pottery clays

Fired cone 6. Bodies from Standard, Sheffield, Laguna.

Typecodes

C6-Cone 6 Glazes

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="G2934 Super Durable #2" id="159276" key="vmd4TgdG" date="2019-08-06" typecodes="C6" codenum="G2934Y4" email="zeega.tomc@gmail.com" picturebasename=""> <recipelines> <recipeline material="Ferro Frit 3110" amount="9.000"/> <recipeline material="Wollastonite" amount="21.000"/> <recipeline material="Silverline Talc" amount="14.000"/> <recipeline material="Bentonite" amount="2.000"/> <recipeline material="Silica" amount="23.000"/> <recipeline material="Calcined Alumina" amount="10.000"/> <recipeline material="EPK" amount="12.000"/> <recipeline material="Ferro Frit 3249" amount="9.000"/> </recipelines> </recipe> </recipes>

Born: 2014-03-21, Modified: 2019-08-06 13:19:39