Cone 10R Base Engobe

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

These two variations of the recipe match fired shrinkages to the specifically named bodies (of course, they should fit any body having a similar fired shrinkage). For a zero-porosity porcelain (e.g. Grolleg), try increasing nepheline to 20 at the expense of ball clay.


White/Black Cone 10 Engobe Recipe

For Plainsman H550, H450

Code #

L3954N

Batch #

3

Materials Amt
Nepheline Syenite 10.000 9.80%
Silica 20.000 19.61%
Ball Clay 60.000 58.82%
Zircopax 10.000 9.80%
Bentonite 2.000 1.96%

Total:102.00

Auto Unity Formula + Analysis

CaO 0.03 0.26%
MgO 0.03 0.23%
K2O 0.06 1.00%
Na2O 0.12 1.26%
(KNaO) 0.18
TiO2 0.04 0.59%
Al2O3 1.00 17.40%
SiO2 6.31 64.68%
Fe2O3 0.02 0.67%
ZrO2 0.31 6.59%

Ratios

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

Expansion

5.4 (Molar:5.0)

LOI

7.3

Notes

*This is the product of a series of tests where the percentage of nepheline syenite was progressively reduced (from 25% originally) to reduce the firing shrinkage of to match H550 (it is important that engobes shrink the same as the body or they will flake or crack off during firing or later during ware use). Amazingly only 10% nepheline syenite is needed to make this fit Plainsman H450, H550. Again, do not use this recipe on porcelains (e.g. P700) or whitewares (e.g. H570, P600), the recipe needs more nepheline for them (to increase firing shrinkage, we have another recipe, L3954J that does this).

This engobe is very plastic so it sticks well to leather hard clay.

The zircopax makes this fire quite white. If you want black, switch it to 5-10% Mason 6600. Be careful with other stains, some of them will flux and increase the fired shrinkage.

To mix this follow the instructions on using an engobe at the Digitalfire Reference Library. Our approximate recipe is: Mixed 3000 grams powder with 2380 water to get SG 1.47. Darvan 9.5g. That amount of Darvan works in our studio with our water and material (yours will be different). Start with with 8.0 and add more until it is thin enough. Be super careful not to add too much (if you do it might be necessary to thicken the engobe with some Epsom salts, but again, a little at a time to avoid gelling it).

Pictures

Variations

1 - Black

We normally use 10% black stain, but have tested lesser amounts down to 5%. Just use as much as you need to get the degree of black you want.

Testdata

SHAB - Shrinkage/Absorption

FLEN FWT BWT CONE DSHR FSHR ABS
12 85.43 43.26 43.88 10R 1.4%

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="White/Black Cone 10 Engobe Recipe" keywords="For Plainsman H550, H450" id="136925" key="NfyyofPk" date="2021-02-01" codenum="L3954N"> <recipelines> <recipeline material="Nepheline Syenite" amount="10.000" tolerance=""/> <recipeline material="Silica" amount="20.000" tolerance=""/> <recipeline material="Ball Clay" amount="60.000" tolerance=""/> <recipeline material="Zircopax" amount="10.000" tolerance=""/> <recipeline material="Bentonite" amount="2.000" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2016-12-12, Modified: 2021-02-01 16:05:13

Black Cone 10 Whiteware Engobe Recipe

For Plainsman H570

Code #

L3954J

Batch #

3

Materials Amt
Nepheline Syenite 15.000 15.08%
Silica 15.000 15.08%
Ball Clay 57.000 57.29%
*Mason 6600 Black 10.000 10.05%
Bentonite 2.500 2.51%

Total:99.50

Notes

*This is a variation on L3954N. This has a higher fired shrinkage to match more vitreous bodies (like Plainsman H570, P580 which have 0.5-1% fired porosity). However this does not shrink enough to match a vitreous Grolleg porcelain (like P700), more nepheline would be needed.

Batch Ticket Notes

Mixed 3000 grams powder. with 2380 water to get SG 1.47. Darvan 9.5g.

April 10/18 Joe tried a gum version:
L3954J powder 500 gms.
Water 280 grams
Laguna Gum Solution 75 grams.
This just so fits in a 1 pint jar.

This flakes on the insides of P700 pieces and pulls dramatically toward itself on an EBCT with P700.

Pictures

H570 P6629 has no solubles, works with black slip

L3954J engobe fit is perfect (as can be seen on the straight CLWC engobe compatibility test bars. Something is wrong because the engobe shrinks 2% more on firing.

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.

L3954J Engobe fit cone 10R

Back to front: H450, H550, H570 and white version of same engobe For some reason the fit is almost perfect on all except H550 (toward 550 on drying, toward J on firing for a total of 7mm).

L3954J and H are compatible

The black stain is not changing the fired shrinkage.

G2571A of black and brown L3954 engobe

On H450 at cone 10R

L3954 cone 10R engobe fired bars

On P700 flakes inside, outside OK

The shrinkage difference is not great enough for this dramatic result so the engobe is not forming a good bond with the porcelain.

With P700

Pulls 11 toward the J on drying and then back straight on firing. That means the J needs less firing shrinkage, more drying shrinkage to work with P700.

Testdata

SHAB - Shrinkage/Absorption

DLEN FLEN FWT BWT CONE DSHR FSHR ABS
8 94.04 86.65 39.7 39.74 8.0 6.0% 7.9% 0.1%
10 94.16 87.71 39.22 40.94 10.0 5.8% 6.9% 4.4%
12 94.18 86.36 37.77 37.77 10R 5.8% 8.3% 0.0%

EBCT - Engobe Body Compatibility Test

MATA MATB BNDR BNFR BCON
1 engobe H450 4.7/450 2/450 10R
2 engobe H570 .5/570 .7/570 10R
3 G3954H G3954J 3mm/J 1.5mm/J 10R
4 H55O L3954J 3.5/H550 3.5/J 10R
5 P700 L3954J 11/J 0/J 10R

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Black Cone 10 Whiteware Engobe Recipe" keywords="For Plainsman H570" id="130962" key="gC6Nr8HL" date="2021-02-01" codenum="L3954J"> <recipelines> <recipeline material="Nepheline Syenite" amount="15.000" tolerance=""/> <recipeline material="Silica" amount="15.000" tolerance=""/> <recipeline material="Ball Clay" amount="57.000" tolerance=""/> <recipeline material="Mason 6600 Black" amount="10.000" tolerance=""/> <recipeline material="Bentonite" amount="2.500" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2016-12-12, Modified: 2021-02-01 16:05:19

Variation of Recipe L3954N

White/Black Cone 10 Engobe Recipe

Code Number Extension

L3954N - 1

Recipe Name Extension

Black


Base Recipe For This Variation

Materials Amt
Nepheline Syenite 10.000 9.80%
Silica 20.000 19.61%
Ball Clay 60.000 58.82%
Zircopax 10.000 9.80%
Bentonite 2.000 1.96%
Additions Amt
Mason 6600 10.000 9.80%

Total:112.00

Auto Unity Formula + Analysis

CaO 0.03 0.26%
MgO 0.03 0.23%
K2O 0.06 1.00%
Na2O 0.12 1.26%
(KNaO) 0.18
TiO2 0.04 0.59%
Al2O3 1.00 17.40%
SiO2 6.31 64.68%
Fe2O3 0.02 0.67%
ZrO2 0.31 6.59%

Ratios

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

Expansion

5.4 (Molar:5.0)

LOI

7.3

Cost

4.54 per kg

Notes for this variation

We normally use 10% black stain, but have tested lesser amounts down to 5%. Just use as much as you need to get the degree of black you want.

Pictures

L3954N black On L4048A H550

L3954N Black on L4048A H550 Test

Black cone 10R slip fired bar

Testdata

SHAB - Shrinkage/Absorption

DLEN FLEN FWT BWT CONE DSHR FSHR ABS
12 92.77 85.43 43.26 43.88 10.5R 7.2% 7.9% 1.4%

EBCT - Engobe Body Compatibility Test

MATA MATB BNDR
1 L4050A L3954N-1 15/L4050A
2 L4048A L3954N 10/L4048A