Ceramic Grade Feldspar Exports To Vietnam By Aalok Overseas India

Frit Producers — Are Pinholes & Blisters Eating Into Your Yield?

You’ve adjusted the firing curve. Tweaked soaking time. Checked kiln atmosphere.

And the pinholes are still there.

At some point, it’s worth asking:

Is this really a process issue — or a raw material issue?
🔬 What’s Happening Inside the Kiln
Pinholes form when gases move through the glaze and escape at the surface before it has time to heal.

Blisters occur when gases get trapped due to surface tension and viscosity imbalance.

These are not just firing issues — they are strongly influenced by:
Melt viscosity
Surface tension
Particle size distribution
And one raw material plays a major role in all three: feldspar.

⚠️ Where Feldspar Starts Affecting the Outcome
Variations in feldspar — even small ones — can shift glaze behavior:
🔴 Impurities (like Fe₂O₃) can introduce gas evolution during firing
🔴 Inconsistent alkali balance (Na₂O / K₂O) can change melt fluidity
🔴 Non-uniform particle size can lead to uneven melting zones
🔴 Trace contamination can impact colour stability in light glazes

In frit production, these effects often show up as:
→ Surface defects
→ Batch variability
→ Process adjustments that don’t fully solve the issue

📊 Why This Matters More Than It Seems
Frit formulations are usually stable on paper.
But in practice, raw material consistency defines whether that formulation performs predictably or not.

Even when parameters look similar in reports, differences in:
Mineral structure
Impurity distribution
Grinding consistency
Can influence real production outcomes.

💡 A Practical Takeaway
When troubleshooting glaze defects:
Instead of only adjusting firing curves or recipes, it’s worth evaluating:
→ Raw material consistency
→ Chemical stability across batches
→ Behavior during actual melting (not just lab values)