Orton 3 Hole Plaque for Large Cones

Orton 3 Hole Plaque for Large Cones

An Orton 3-Hole Plaque is a ceramic holder designed to support Large Regular Base (LRB) Pyrometric Cones in a kiln. It ensures that the cones are positioned correctly for accurate heatwork measurement.

How to Use an Orton 3-Hole Plaque with LRB Cones:

1. Insert the Cones – Place the LRB cones into the three angled holes of the plaque. The cones should be inserted so that they lean slightly (about 8° forward).
2. Position in the Kiln – Set the plaque on a kiln shelf in a location that represents the general heat distribution of the kiln.
3. Cone Selection – Typically, three cones are used:
   • Guide Cone (Lower temperature than target) – Starts bending first to indicate the approach of the firing range.
   • Firing Cone (Target temperature cone) – Bends at the correct heatwork level.
   • Guard Cone (Higher temperature than target) – Helps ensure over-firing doesn’t occur.
4. Observe the Results – After the firing cycle, check the bending pattern of the cones:
   • A properly fired cone should bend to about 90 degrees.
   • If under-fired, the cone will remain upright or only slightly bent.
   • If over-fired, the cone will bend too much or collapse.

Using a 3-Hole Plaque with LRB cones provides a consistent and stable way to track firing accuracy across different kiln loads.