Client Background
The client — a mid-sized ceramic tile manufacturer based in the Morbi ceramic cluster of Gujarat, India — operates two production lines focused on polished and glazed wall tiles in 600×600mm and 600×1200mm formats. Monthly output at the start of the engagement was approximately 320,000 square meters, of which roughly 60,000 sqm was being lost to firing defects, dimensional instability, and surface quality issues.
The plant's technical manager had been experimenting with body formulation adjustments for over a year without achieving consistent improvement. Rejection rates were fluctuating between 17% and 22% depending on the kiln cycle and raw material batch.
The Challenge
Before engaging Dragon Chemical, the plant's body formulation relied heavily on calcium carbonate as the primary calcium source, with plastic clays and feldspar completing the recipe. Three persistent problems were eroding margins:
- High firing shrinkage variance: tiles in the same kiln cycle were shrinking inconsistently, causing out-of-tolerance dimensional rejects of 4-6% per cycle.
- Surface defects after polishing: pinholes and micro-craters appeared in approximately 8-10% of polished tiles, requiring rework or downgrading.
- Moisture sensitivity in green body: cracking during drying accounted for an additional 3-4% loss before tiles even entered the kiln.
Cumulative wastage was sitting at 18-19% of total production, against an industry benchmark of 10-12% for comparable product mixes in the Morbi cluster.
Calcium carbonate releases CO₂ during firing (Loss on Ignition ~43%), contributing to gas-evolution defects like pinholes and blisters. It also requires higher firing temperatures to fully decompose, increasing energy cost per square meter. Wollastonite — a natural calcium silicate — contains no volatile components and contributes calcium without gas evolution.
Our Approach
Dragon Chemical's Technical Division, led by Mr. Naveen and Mr. Manoj, conducted a 3-day on-site diagnostic at the client's Morbi facility in October 2025. The engagement followed our standard 4-stage technical collaboration process:
Body formulation audit
Reviewed the existing recipe, raw material sources, particle size distributions and firing curve. Identified calcium carbonate as the primary contributor to gas-evolution defects. Mapped the relationship between body moisture, drying schedule and green-body cracking.
Laboratory trials
Prepared three body formulations in our Foshan R&D lab — partial replacement (35%), substantial replacement (65%), and full replacement (100%) of calcium carbonate with W3 wollastonite grade. Tested firing behavior at 1180°C, 1200°C and 1220°C. Measured shrinkage, water absorption, MOR (modulus of rupture), and surface quality after polishing.
Pilot production run
Trialed the 65% replacement formulation on one production line for a 4-week pilot. Dragon's Technical Division was on-site for the first week of pilot production to fine-tune pressing pressure, drying curve, and kiln setting. Adjusted wollastonite content to 70% based on real-time defect data.
Full rollout and optimization
Rolled out the optimized formulation to both production lines. Continued weekly remote monitoring of defect rates and yield data. Made incremental adjustments to feldspar content (reduced from 22% to 19%) to compensate for the lower flux contribution of wollastonite. By week 12, the plant was operating at steady-state with the new formulation.
The Solution: W3 Wollastonite Grade
Based on the lab trials and pilot production data, the formulation adjustment centered on Dragon Chemical's W3 wollastonite grade — selected for its higher opacity and brighter L-value (96.5), which suited the client's polished tile product mix. Key characteristics of W3 in the new body formulation:
| Parameter | Specification | Why it mattered for this client |
|---|---|---|
| Whiteness (ISO) | 85.0% | Brighter body, less glaze opacity needed |
| L-value | 96.50 | Consistent polished tile appearance |
| Loss on Ignition | < 2.0% | Negligible gas evolution during firing |
| Particle size (D50) | ~12 µm | Improved pressing density, less cracking |
| Free CaO | < 1.5% | Stable hydration behavior in slip |
Results — Before vs After
After 90 days of full production with the new wollastonite-optimized body, the plant achieved measurable improvements across every key metric tracked by their quality team:
| Metric | Before | After | Change |
|---|---|---|---|
| Total wastage rate | 18.8% | 13.5% | −28% |
| First-pass yield | 81.2% | 89.9% | +8.7 pts |
| Dimensional rejects | 5.4% | 1.9% | −65% |
| Pinhole / blister defects | 9.2% | 3.1% | −66% |
| Green-body cracking | 3.7% | 1.4% | −62% |
| Kiln firing temperature | 1218°C | 1195°C | −23°C |
| Energy cost per sqm | Baseline | −9% | −9% |
| Cost per sqm (full recipe) | Baseline | −18% | −18% |
Wastage rate trajectory — 24 weeks of observation
Wastage rate measured weekly across both production lines. Implementation began week 1; full rollout completed by week 6. Steady-state achieved by week 12 and sustained through week 24 (end of observation period).
"Dragon's team didn't just sell us a mineral — they spent three weeks on our plant floor. The wollastonite switch was the catalyst, but the body formulation work and kiln curve adjustments they made alongside it were what actually delivered the 28% reduction. We had tried switching raw materials before. The difference this time was the technical depth."
— Technical Manager, Morbi ceramic tile manufacturer(Name withheld at client's request. Case study verified through plant records and yield data.)
Why It Worked
Three factors combined to deliver the result. None of them alone would have been sufficient.
1. The mineral itself
Wollastonite's near-zero Loss on Ignition eliminated the gas evolution that was causing pinholes and blisters during firing. Its acicular (needle-like) crystal structure also improved green-body strength, which directly addressed the cracking-during-drying problem.
2. The formulation adjustment
Wollastonite has lower flux contribution than the calcium carbonate it replaced. The Technical Division's adjustment to feldspar content — reducing from 22% to 19% — was counter-intuitive but essential: it compensated for the wollastonite's refractory behavior while maintaining the firing range the kiln operators were used to.
3. The process adjustments
The kiln firing temperature was lowered by 23°C, and the drying schedule was extended by 8 minutes. Both changes were small in isolation but compound into a meaningful energy saving and a measurable reduction in thermal-shock defects.
The pilot phase revealed that wollastonite's lower plasticity affected slip viscosity earlier than expected. In future engagements, we would adjust deflocculant dosage during the slip preparation stage from day one, rather than waiting for the green-body cracking signal. This would compress the timeline by approximately 2 weeks.
Applicability — Does This Apply to Your Plant?
This case study is most directly applicable to ceramic tile manufacturers facing:
- Wastage rates above 15% on polished or glazed tile lines
- Body formulations using calcium carbonate as the primary calcium source
- Pinhole, blister, or micro-crater defects in glazed or polished surfaces
- Dimensional instability or shrinkage variance in large-format tiles (600×600mm and above)
If your plant's challenges match two or more of the above, a wollastonite body optimization program is likely to deliver similar results. Our Technical Division offers a no-commitment diagnostic visit — we will review your current body formulation, kiln curve and defect data, and provide a written assessment of the improvement opportunity before you decide whether to proceed.
Want a diagnostic visit for your plant?
Our Technical Division visits ceramic plants across India, Southeast Asia, Middle East and Africa. Tell us about your current wastage rate and product mix — we'll respond within 24 hours.
Request a free diagnostic →Methodology & Verification
All data in this case study was collected from the client's own quality control records and verified by Dragon Chemical's Technical Division during on-site visits. Wastage rates are calculated as (input − saleable output) ÷ input, measured at the kiln exit and again after polishing. Yield figures exclude intentionally downgraded product. Energy and cost-per-sqm calculations were provided by the client's production accounting team and are presented as relative changes against the pre-implementation baseline.
The client reviewed and approved the data presented in this case study prior to publication. Identifying details have been withheld at the client's request; the Technical Manager's quote is reproduced with permission.
Frequently Asked Questions
How much wastage reduction did the Morbi plant achieve with wollastonite?
The Morbi ceramic tile plant reduced production wastage by 28% over a 90-day period, improving first-pass yield from 81% to 89.9% after switching to Dragon Chemical's W3 wollastonite grade and implementing body formulation adjustments recommended by our Technical Division.
How long does it take to see results after switching to wollastonite?
In this case study, the Morbi plant saw measurable improvements within 4 weeks of implementation, with full 28% wastage reduction achieved by week 12. Timeline depends on plant size, current formulation complexity, and intensity of technical support.
What is the cost-benefit of switching to wollastonite-based body formulation?
The Morbi plant reported ROI within 60 days of full implementation. Wastage reduction of 28% combined with lower rejection rates translated to approximately 18-22% reduction in cost-per-square-meter of finished tile, before accounting for the labor and energy savings from reduced rework.