Making your own pyrometric cones

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

This is not a chemistry project, it is about an organized program of physical testing and record keeping to develop body recipes for various common cones.


Project Name

Making Our Own Pyrometric Cones

Project Codenumber

UnAssigned

Notes

This page is about developing the recipes for making cones. First, I want to develop a mix that bends correctly at cone 6. Then develop rules on how much to increase and decrease the frit to adjust for bending at cones 7-10 and 2-5. Or, it might be better to develop a recipe that works for cone 10 and then make the intermediate cones by mixes of the 6 and 10.

It seems logical that the body recipe would contain frit to control melting range, clay to impart plastic forming properties, feldspar and silica as fillers to stabilize against temperature response volatility. And of course gums or binders to provide dry hardness (of course, homemade cones could be more fragile since they do not need to survive a lot of handling). That being said, dry cast cones may turn out to be stronger than expected.

Pyrometric cone pressing body #2

Code #

L4532A

Materials Amt
Nepheline Syenite 25.000 22.12%
Pioneer Kaolin 40.000 35.40%
Silica 25.000 22.12%
Fusion Frit F-75 20.000 17.70%
Veegum 3.000 2.65%

Total:113.00

Auto Unity Formula + Analysis

CaO 0.20 1.40%
MgO 0.01 0.06%
K2O 0.12 1.43%
Na2O 0.66 5.06%
(KNaO) 0.79
TiO2 0.05 0.51%
B2O3 0.05 0.46%
Al2O3 1.59 19.94%
SiO2 8.90 65.89%
Fe2O3 0.01 0.17%

Ratios

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

Expansion

6.6 (Molar:6.5)

LOI

5.1

Notes

*This is version 2 of the series, it doubles the initial frit percentage and adds VeeGum as a plasticizer (and removes CMC gum). It is possible to press this into the 3D printed molds when it is very stiff. However drying is an issue, the top thinner section is drying first and sometimes cracking away partway down.

Clearly, this recipe change is going in the right direction, this cone is almost bending enough at cone 7.

Pictures

L4532A at cone 7

An orton cone on the left, this trial on the right. This is almost bending enough at cone 7.

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Pyrometric cone pressing body #2" id="221646" key="u8swbKku" date="2022-08-16" codenum="L4532A"> <recipelines> <recipeline material="Nepheline Syenite" amount="25.000" tolerance=""/> <recipeline material="Pioneer Kaolin" amount="40.000" tolerance=""/> <recipeline material="Silica" amount="25.000" tolerance=""/> <recipeline material="Fusion Frit F-75" amount="20.000" tolerance=""/> <recipeline material="Veegum" amount="3.000" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2021-03-08, Modified: 2022-08-16 19:05:34

Cone pressing body #3

Code #

L4532B

Materials Amt
Nepheline Syenite 20.000 19.32%
Pioneer Kaolin 35.000 33.82%
Silica 20.000 19.32%
Fusion Frit F-75 25.000 24.15%
Veegum 3.500 3.38%

Total:103.50

Auto Unity Formula + Analysis

CaO 0.23 1.81%
MgO 0.01 0.06%
K2O 0.11 1.45%
Na2O 0.66 5.83%
(KNaO) 0.76
TiO2 0.04 0.49%
B2O3 0.06 0.63%
Al2O3 1.30 19.03%
SiO2 7.63 65.68%
Fe2O3 0.01 0.16%

Ratios

Si:Al: 5.9:1
SiB:Al: 5.9:1
R2O:RO: 0.8:0.2

Expansion

7.0 (Molar:6.8)

LOI

4.9

Notes

*The recipe has been retotalled to 100 (plus the Veegum) and the frit has been increased at the expense of silica. This should be plenty to bend it too much at cone 6. Then a blend of this and L4532A will produce the desired recipe.

Pictures

L4532A and L4532B at cone 6 (with Orton cone 6)

L4532B at cone 5 (with Orton cone 5)

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Cone pressing body #3" id="221717" key="hhcRCNEv" date="2022-08-16" codenum="L4532B"> <recipelines> <recipeline material="Nepheline Syenite" amount="20.000" tolerance=""/> <recipeline material="Pioneer Kaolin" amount="35.000" tolerance=""/> <recipeline material="Silica" amount="20.000" tolerance=""/> <recipeline material="Fusion Frit F-75" amount="25.000" tolerance=""/> <recipeline material="Veegum" amount="3.500" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2021-03-08, Modified: 2022-08-16 19:07:20

Cone pressing body #5

Code #

L4532D

Materials Amt
Nepheline Syenite 22.500 20.98%
Pioneer Kaolin 37.500 34.97%
Silica 22.500 20.98%
Fusion Frit F-75 21.500 20.05%
Veegum 3.250 3.03%

Total:107.25

Auto Unity Formula + Analysis

CaO 0.21 1.55%
MgO 0.01 0.06%
K2O 0.12 1.43%
Na2O 0.66 5.33%
(KNaO) 0.78
TiO2 0.05 0.51%
B2O3 0.06 0.52%
Al2O3 1.48 19.66%
SiO2 8.40 65.75%
Fe2O3 0.01 0.17%

Ratios

Si:Al: 5.7:1
SiB:Al: 5.7:1
R2O:RO: 0.8:0.2

Expansion

6.8 (Molar:6.6)

LOI

5.0

Notes

*In comparing this with L4532B, which bent correctly at cone 5, this has 3.5% less frit, and is bending correctly (like the Orton) at cone 6.

It is going to be a learning process to decide whether to vary the percentage of frit, trade the frit for another ingredient, focus on the chemical analysis or the chemical formula.

The casting version of this uses 1% Veegum (instead of 3.25%) and we add 5.5g Darvan to 250g water and blender mix 500g powder into that. This produces a 1.7 specific gravity. Each cone weighs about 6g when dry.

Pictures

L4532D cone at cone 6

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Cone pressing body #5" id="222636" key="ioZ8dpgv" date="2022-10-04" codenum="L4532D"> <recipelines> <recipeline material="Nepheline Syenite" amount="22.500" tolerance=""/> <recipeline material="Pioneer Kaolin" amount="37.500" tolerance=""/> <recipeline material="Silica" amount="22.500" tolerance=""/> <recipeline material="Fusion Frit F-75" amount="21.500" tolerance=""/> <recipeline material="Veegum" amount="3.250" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2021-03-08, Modified: 2022-10-04 13:01:57

Cone 5 Cone-casting v.1

Code #

L4532F

Materials Amt
Nepheline Syenite 22.500 21.63%
OM4 Ball Clay 37.500 36.06%
Silica 22.500 21.63%
Fusion Frit F-75 21.500 20.67%

Total:104.00

Notes

*Releasing from the mold better.

This is bending at cone 5.

Using ball clay instead of kaolin has removed the need for the Veegum and has increased bending by at least a cone.

Pictures

L4532F at cone 5 and 6

The rear cones are Orton 5 and 6.
The front ones are L4532F, bending too much at six and not quite enough at cone 5.

XML (to paste into Insight)

<?xml version="1.0"?> <recipes version="1.0" encoding="UTF-8"> <recipe name="Cone 5 Cone-casting v.1" id="224470" key="Qr5iomNE" date="2022-11-18" codenum="L4532F"> <recipelines> <recipeline material="Nepheline Syenite" amount="22.500" tolerance=""/> <recipeline material="OM4 Ball Clay" amount="37.500" tolerance=""/> <recipeline material="Silica" amount="22.500" tolerance=""/> <recipeline material="Fusion Frit F-75" amount="21.500" tolerance=""/> </recipelines> </recipe> </recipes>

Born: 2021-03-08, Modified: 2022-11-18 14:05:14