Question

Lead glaze are fire at which range of cone temperature?

• A. Cone010 to cone-2
• B. Cone012 to con -06
• C. Cone 06 to cone -4
• D. Cone012 to con -6

Hint:

Logic Tip: Lead is a super-melter. It goes on low-fire earthenware, which is almost universally fired in the Cone 06 to Cone 04 range.

Answer 1

The Correct Option is C

Concept:
Lead has historically been used in ceramics as a powerful flux. A flux is a material that lowers the melting point of silica to create glass (glaze).

Step 1:
Lead oxide is an incredibly strong flux. It causes glazes to melt beautifully, lay flat, and produce brilliant, vibrant colors. Because it is so powerful, it requires very little heat to melt.

Step 2:
Because lead fluxes so easily, lead glazes are strictly classified as low-fire glazes. If fired too hot, the lead will literally boil, vaporize, and blister.

Step 3:
The standard low-fire temperature range for traditional earthenware and lead glazes in studio practice falls right in the middle of the low-fire spectrum, generally between $990^{\circ}C$ and $1060^{\circ}C$.

Step 4:
Looking at the standard pyrometric cone chart:
• Cone 06 is approximately $999^{\circ}C$
• Cone 04 is approximately $1060^{\circ}C$ This range (Cone 06 to 04) is the classic sweet spot where lead glazes mature perfectly without volatilizing into dangerous gasses.

Step 5:
Therefore, the correct standard firing range for lead glazes is Cone 06 to Cone 04. \[ \boxed{\text{(3) Cone 06 to cone -4}} \]