Ravenscrag Slip cone 6 base pottery glaze - Adjustable using two frits

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

See Also:
Cone 6 white matte and glossy that do not crawl

The original employed frit 3134 however a newer version incorporates frit 3249 to lower thermal expansion. Add opacifiers to produce an awesome ivory white.


Ravenscrag Original Cone 6 Base Glaze

Code #

G2936C

Materials Amt
Ravenscrag Slip 50.000
Ravenscrag Slip 1000F Roast 30.000
Ferro Frit 3134 20.000

Total:100.00

Auto Unity Formula

CaO 0.68
MgO 0.11
K2O 0.08
Na2O 0.12
(KNaO) 0.21
TiO2 0.01
B2O3 0.21
Al2O3 0.33
SiO2 3.13
Fe2O3 0.01

Ratios

Si:Al: 9.5:1
SiB:Al: 10.1:1
R2O:RO: 0.2:0.8

Expansion

7.0 (Molar:6.8)

LOI

5.3

Notes

*Also known as GR6-A at PlainsmanClays.com. This differs from a regular clear glaze made from industrial minerals in that the fired appearance is more organic, less sterile.

Crazing: Traditionally we have used Ferro Frit 3134 in this recipe but some people get crazing. Our G2936 variation addresses that problem.

If entrained bubbles are an issue, a 2% addition of Zircopax can be helpful as a fining agent. For white increase the Zircopax to 10% (see G2936 and G2936A).

Ravenscrag Slip suspends well in water and normally one can just mix it 80:20 with a frit. But we have found that this can crack during drying. Thus we use a 50:30 mix of raw:roast Ravenscrag.

Add opacifiers, colorants and variegators to produce all manner of visual effects.

Pictures

GR6-A Ravenscrag Clear cone 6

On M370, M340 and M390.

GR6-A Ravenscrag white cone 6

Adds 10% zirocpax to the GR6-A recipe.
On M370, M340 and M390.

G2936 vs GR6-A - Cone 6 on M370

G2936 vs GR6-A - Cone 6 on M370

On M370

GR6-A on M390 cone 6

Alternate Code Number:GR6-A

Variations

1 - Pink

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Ravenscrag Original Cone 6 Base Glaze" id="56548" key="wz2g2or2" date="2024-05-09" codenum="G2936C"> <recipelines> <recipeline material="Ravenscrag Slip" amount="50.000" tolerance=""/> <recipeline material="Ravenscrag Slip 1000F Roast" amount="30.000" tolerance=""/> <recipeline material="Ferro Frit 3134" amount="20.000" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2014-03-03, Modified: 2024-05-09 02:33:12

Ravenscrag Low Expansion Cone 6 Base

Code #

G2936

Materials Amt
Ravenscrag Slip 80.000
Ferro Frit 3249 20.000

Total:100.00

Auto Unity Formula

CaO 0.55
MgO 0.33
K2O 0.09
Na2O 0.02
(KNaO) 0.11
TiO2 0.01
B2O3 0.29
Al2O3 0.44
SiO2 3.39
Fe2O3 0.01

Ratios

Si:Al: 7.7:1
SiB:Al: 8.4:1
R2O:RO: 0.1:0.9

Expansion

5.9 (Molar:5.6)

LOI

7.0

Notes

*This frit lowers the coefficient of thermal expansion dramatically. And it produces better melted results than the standard Frit 3134 version G2936C (less dimples, surface defects). This thermal expansion is so low that it is likely that a mix of Frit 3134 and 3249 would be best. Tune the mix to fit your clay body (more 3249 if it crazes, more 3134 if it shivers).

The reason this does not use a roast:raw mix is that we mixed it as a brushing glaze using CMC gum.

Pictures

G2936A - Ravenscrag with 20% Frit 3249

Cone 6 PLC6DS firing. Excellent results, no pinholes, bubbles as can happen with frit 3134.

G2936 clear vs G2936A white - Cone 6 PLC6DS firing

G2936 vs G2936A - Cone 6 PLC6DS firing

G2936+ 10% Zircopax at cone 5

P6954 at cone 5 - G3936 inside glaze crazed

Slow cool firing
Outsides: G3903 (AltaSlip + Frit FZ16)
Insides:
G2936 Ravenscrag with Ferro 3249, pleasant matte, quite transparent (crazed over time, very strange, likely needs cone 6).

G2926SX: Needs to be a little thicker application.

G2936 at cone 3

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Ravenscrag Low Expansion Cone 6 Base" id="57080" key="TNaErcai" date="2024-05-09" codenum="G2936" picturebasename=""> <recipelines> <recipeline material="Ravenscrag Slip" amount="80.000" tolerance=""/> <recipeline material="Ferro Frit 3249" amount="20.000" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2014-03-17, Modified: 2024-05-09 02:01:18

Ravenscrag Low Expansion White Base 2

Code #

G2936B

Materials Amt
Ravenscrag Slip 80.000
Ferro Frit 3249 20.000
Additions
Zircopax 5.000
Tin Oxide 3.000

Total:108.00

Auto Unity Formula + Analysis

BaO 0.01 0.22%
CaO 0.55 8.08%
MgO 0.33 3.50%
K2O 0.09 2.21%
Na2O 0.02 0.37%
(KNaO) 0.11
TiO2 0.01 0.29%
B2O3 0.29 5.32%
Al2O3 0.44 11.73%
SiO2 3.48 54.78%
Fe2O3 0.01 0.59%
SnO2 0.07 2.76%
ZrO2 0.10 3.09%

Ratios

Si:Al: 7.9:1
SiB:Al: 8.6:1
R2O:RO: 0.1:0.9

Expansion

5.9 (Molar:5.6)

LOI

7.0

Notes

*This modifies G2936A, which just has 10% Zircopax, whitening using a mix of tin oxide and zircopax, that helps to reduce crawling.

At 1.6 specific gravity with ~0.25% CMC gum this produces a base coat dipping glaze.

For a 500ml jar of brushing glaze we blender-mix 340 powder, 440 water, 5 CMC gum and 3.5 Veegum.

This white variation of the GR6-A glaze can be quite striking (compared to the "toilet bowl" appearances of other whites. The low thermal expansion should eliminate issues with crazing on just about any clay body.

Batch Ticket Notes

Added 0.35% CMC powder to the glaze recipe and mix 110 powder to each 100 water. Much too watery, evaporated down to 1.6SG.

Pictures

G2936B RavenWhite vs G2926B white

G2926B white vs G2936B RavenWhite

G2926B white vs G2936B RavenWhite

G2936B RavenWhite with G3948C over it at cone 6

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Ravenscrag Low Expansion White Base 2" id="224213" key="iMoadC6r" date="2024-05-09" codenum="G2936B" picturebasename=""> <recipelines> <recipeline material="Ravenscrag Slip" amount="80.000" tolerance=""/> <recipeline material="Ferro Frit 3249" amount="20.000" tolerance=""/> <recipeline material="Zircopax" amount="5.000" added="true"/> <recipeline material="Tin Oxide" amount="3.000" added="true"/> </recipelines> </recipe> </recipes>

Born: 2014-03-17, Modified: 2024-05-09 02:04:40