Snakeskin come 6 glaze discovered by accident

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

An example of how a glaze fault, crawling induced by zinc oxide, is actually a mechanism to produce a snakeskin surface


G2934 (glossed using ZnO)

Code #

G2934J1

Materials Amt
Ferro Frit 3110 11.600 13.43%
EPK 22.500 26.04%
Wollastonite 8.300 9.61%
Silica 8.300 9.61%
Zinc Oxide 3.900 4.51%
Silverline Talc (Talc) 16.600 19.21%
Calcined Kaolin 15.200 17.59%

Total:86.40

Auto Unity Formula

CaO 0.29
MgO 0.44
K2O 0.01
Na2O 0.10
(KNaO) 0.11
ZnO 0.16
B2O3 0.01
Al2O3 0.52
SiO2 2.78

Ratios

Si:Al: 5.3:1
SiB:Al: 5.4:1
R2O:RO: 0.1:0.9

Expansion

5.8 (Molar:5.6)

LOI

4.8

Cost

0.00 per kg

Notes

*This removes B2O3, adds Al2O3

Start with 50:50 water:powder mix for a good slurry.

This is going to need some gum to prevent cracking during drying.

Pictures

G2934J1 G2934 glaze cracking badly

Even when very thin.

G2934J1 glaze

Left sample: The J1 on the right is high gloss but when we remixed (right sample) it does not work. Since the intention was to create more matteness than G2934J the gloss one must have been an error.

G2934J1 G2934 on P300

Creating an interesting pattern because of the cracking during drying.

Typecodes

C6-Cone 6 Glazes

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="G2934 (glossed using ZnO)" id="216096" key="YEcxJJY6" date="2023-12-08" typecodes="C6" codenum="G2934J1" picturebasename=""> <recipelines> <recipeline material="Ferro Frit 3110" amount="11.600" tolerance=""/> <recipeline material="EPK" amount="22.500" tolerance=""/> <recipeline material="Wollastonite" amount="8.300" tolerance=""/> <recipeline material="Silica" amount="8.300" tolerance=""/> <recipeline material="Zinc Oxide" amount="3.900" tolerance=""/> <recipeline material="Silverline Talc" lookup="Talc" amount="16.600" tolerance=""/> <recipeline material="Calcined Kaolin" amount="15.200" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2014-03-21, Modified: 2023-12-08 20:53:32

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

Auto Unity Formula + Analysis

CaO 0.54 9.77%
MgO 0.39 5.06%
K2O 0.01 0.19%
Na2O 0.06 1.23%
(KNaO) 0.07
TiO2 0.00 0.07%
P2O5 0.00 0.04%
B2O3 0.12 2.61%
Al2O3 0.45 14.85%
SiO2 2.71 52.42%
Fe2O3 0.00 0.14%

Ratios

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

Expansion

5.8 (Molar:5.7)

LOI

13.6

Cost

0.00 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. In our standard firings this recipe produces both good mattenss and a very functional surface coupled with very low chance of crazing. It is not as interesting as reactive mattes but this is better for functional and durable surfaces. This is also adjustable, the degree of matteness can be controlled by blending in a glossy.

WARNING: The degree-of-matteness is very dependent on cooling rate in the kiln. Fast cooling (e.g. our PLC6DS firing schedule in a lightly-loaded or smaller kiln) produces a silky matte or even glossy surface. Slower cooling (e.g. a heavily loaded kiln or the C6DHSC schedule) may produce a matter surface than you need (which is more subject to cutlery marking). Control the degree of mattness by either adapt the firing curve or blending in some glossy G2926B (simply the slurries pouring together, volumetrically is a good way to determine the ratio needed).

https://plainsmanclays.com/g2934 documents this recipe using a variety of stains.

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

Incredible cone 6 speckle body with G2934 matte glazes

This clay, L4115J3S, a Plainsman 3D-based body, fires vitreous and dense, yet there is no hint of bloating. With these matte glazes very durable and functional pieces are produced.

Outside glaze on both is G2934W (adds 10% zircopax). In our C6DHSC firings this produces as matte a surface as is possible without having excessive staining problems. To add a little gloss we blend in 15% of the G2926B Glossy clear.

Inside glazes:
Left mug: L4423A (85:15 mix of G2934 matte/G2926B clear glossy). It does not contain any zircopax.
Right mug: G2926B ball milled glossy, producing a striking visual yet highly functional surface.

These mugs look as close to cone 10R dolomite-glazed ware as we have ever seen! Especially the L4423A recipe

Melt flow comparison: G2934 with Frit 3124, Frit F-19

Fusion Frit F-19 is giving a more fluid melt.

The difference cooling-rate makes

These are the G2934 black glaze at cone 6. The piece on the left was fired using the C6DHSC firing schedule (drop-and-hold at 2100F then 150F/hr to 1400F). The one on the right was fired using the PLC6DS schedule (drop-and-hold at 2100F then free-fall from there). The slow cool gives the glaze on the left time to crystallize, creating a stony matte.

G2934 Cone 6 Matte + 4% iron oxide

Left: PLC6DS firing
Right: C6DHSC firing

URLs

Prepared public do..om Plainsman Clays

Typecodes

C6-Cone 6 Glazes

Alternate Code Number:MG6CDM

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="KAmBXHig" date="2024-03-08" typecodes="C6" codenum="G2934" picturebasename=""> <recipelines> <recipeline material="Ferro Frit 3124" amount="19.400" tolerance=""/> <recipeline material="EPK" amount="18.300" tolerance=""/> <recipeline material="Dolomite" amount="23.500" tolerance=""/> <recipeline material="Silica" amount="26.960" tolerance=""/> <recipeline material="Calcined Kaolin" amount="13.900" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2014-03-21, Modified: 2024-03-08 20:40:00

G2934 with ZnO for Brown Stains

Code #

G2934J

Materials Amt
Fusion Frit F-19 23.600
EPK 22.500
Wollastonite 8.300
Silica 13.300
Zinc Oxide 4.400
Silverline Talc (Talc) 16.600
Calcined Kaolin 11.200

Total:99.90

Auto Unity Formula

CaO 0.38
MgO 0.38
Na2O 0.08
(KNaO) 0.08
ZnO 0.16
B2O3 0.14
Al2O3 0.45
SiO2 2.76

Ratios

Si:Al: 6.1:1
SiB:Al: 6.5:1
R2O:RO: 0.1:0.9

Expansion

5.7 (Molar:5.6)

LOI

4.1

Cost

0.00 per kg

Notes

*Glossy at cone 6 and 8. Needs more MgO, less SiO2, more Al2O3, less B2O3.

Pictures

G2934J at cone 6 on M370 is firing ultra gloss

Typecodes

C6-Cone 6 Glazes

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="G2934 with ZnO for Brown Stains" id="215445" key="19sjkki2" date="2022-05-26" typecodes="C6" codenum="G2934J" picturebasename=""> <recipelines> <recipeline material="Fusion Frit F-19" amount="23.600" tolerance=""/> <recipeline material="EPK" amount="22.500" tolerance=""/> <recipeline material="Wollastonite" amount="8.300" tolerance=""/> <recipeline material="Silica" amount="13.300" tolerance=""/> <recipeline material="Zinc Oxide" amount="4.400" tolerance=""/> <recipeline material="Silverline Talc" lookup="Talc" amount="16.600" tolerance=""/> <recipeline material="Calcined Kaolin" amount="11.200" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2014-03-21, Modified: 2022-05-26 18:59:41