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Calcined Talc

Classification：

Product

Product Model：

91#,88#,90#,93#

Usage: Widely used in ceramics, coatings, plastics, rubber, paper and other industries as functional filler or reinforcing material. Recommended dosage: Depends on different industries and product formulas. Usually about 15%-35% is added in plastic modification, about 1%-10% is added in ceramic body, and about 5%-20% is added in coating. Advantages: It has good chemical stability and thermal stability; it can effectively improve the hardness, rigidity and dimensional stability of products; it reduces production costs; it has good dispersion and weather resistance. Appearance: white or off-white fine powder, smooth to the touch. Packaging: Packed in 25kg or 50kg laminated woven bags
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Calcined Talc

PRODUCT DETAILS

Overview | Core Specs | Selection Guide | Product Details | FAQ | Inquiry

Calcined Talc for Ceramics: MgO Flux Grades & Whiteness Selection

Four precision grades — 93# (95.3% whiteness), 91# (32.1% MgO), 90# (92.8% whiteness), 88# (cost-balance) — engineered for ceramic body and glaze formulations. High MgO content lowers firing temperature and improves thermal shock resistance. Batch-specific COA, TDS and SDS available from Goway.

Match Your Project to the Right Grade Request TDS / COA / Sample

What Is Calcined Talc Used for in Ceramics?

Calcined talc is a heat-treated magnesium silicate mineral widely used as flux and structural filler in ceramic body and glaze formulations.

Quick Answer: Calcined talc is used to lower ceramic body and glaze firing temperatures by 20–60°C through its MgO fluxing action, improve thermal shock resistance, and contribute to whiteness (up to 95.3% depending on grade). Typical dosage in ceramic bodies: 5–20%; in glazes: 5–15%.

Talc (Mg₃Si₄O₁₀(OH)₂) is the primary industrial source of MgO in ceramic formulations. Raw talc contains chemically bound water (hydroxyl groups) that is released during firing, causing unpredictable shrinkage and potential defects such as pinholing or bloating. Calcination at 900–1050°C eliminates this bound water before use, making the material chemically stable and dimensionally predictable during ceramic firing.

In ceramic body formulations, calcined talc serves three primary functions:

  • Fluxing agent: MgO (28.8–32.1% depending on grade) lowers the liquid-phase formation temperature, reducing energy consumption and kiln cycle time.
  • Structural filler: SiO₂ (64.7–66.5%) contributes to the aluminosilicate framework, providing body strength and dry integrity.
  • Thermal shock modifier: Talc-containing bodies develop lower thermal expansion coefficients, improving resistance to cracking during rapid firing or cooling cycles.

In ceramic glazes, calcined talc contributes MgO as a flux component, enhances scratch resistance, and produces matte or satin surface finishes when used at appropriate concentrations. (Goway in-house testing, 2025.)

Calcined Talc vs. Raw Talc in Ceramic Bodies

Understanding the critical differences helps you select the correct material for your ceramic formulation.

Table 1 — Calcined Talc vs. Raw Talc: Key Differences in Ceramic Applications
Property Calcined Talc Raw Talc
Bound Water (LOI) 0.11–0.57% (low) 4.5–5.5% (high)
Chemical Stability High — pre-stabilized at 900–1050°C Releases water during firing
Body Shrinkage Controlled, reduced by 2–4% Higher and less predictable
Glaze Melting Behavior Consistent, predictable fluxing Inconsistent, risk of pinholes
Thermal Shock Resistance Improved Moderate
Typical Use in Ceramics Preferred for body and glaze formulations Limited to specialized applications

Practical guidance: For production-scale ceramic body and glaze formulations, calcined talc is the standard choice due to its predictable behavior and consistent quality. Raw talc may be considered for low-cost applications where formulation control is less critical, but the risk of defects from water release typically outweighs the cost saving. (Goway in-house testing, 2025.)

Complete Chemical & Physical Specifications

All data from Goway in-house quality control. Every batch verified before dispatch with batch-specific COA.

Quality Statement

Goway calcined talc products are produced under ISO-quality-controlled conditions. Purity levels and particle size distributions are optimized for ceramic applications. Fe₂O₃ and Al₂O₃ content directly affects final ceramic color — select grade based on your whiteness target.

Table 2 — Goway Calcined Talc Chemical Specifications (Source: Goway Technical Data Sheet, 2025)
Parameter 93#
Ultra-White Premium		 90#
High Whiteness		 91#
High MgO		 88#
Balanced Cost
Whiteness (1200°C) 95.3 92.8 90.3 88.8
SiO₂ (%) 65.7 65.84 64.71 66.45
MgO (%) 31.09 28.8 32.1 29.2
CaO (%) 2.57 3.3 0.73 2.55
Al₂O₃ (%) 0.12 0.98 1.59 0.92
Fe₂O₃ (%) 0.04 0.03 0.29 0.07
Na₂O (%) 0.01 0.01 0.12 0.01
K₂O (%) 0.01 0.02 0.22 0.01
L.O.I (%) 0.31 0.57 0.11 0.57

Whiteness measured at 1200°C firing temperature. All values from Goway in-house QC testing. Request batch-specific COA for delivery verification.

How MgO in Calcined Talc Lowers Firing Temperature

MgO content is the primary driver of fluxing strength in calcined talc. Understanding this relationship helps optimize energy consumption and kiln throughput.

Magnesium oxide (MgO) acts as an intermediate flux in ceramic systems. Unlike strong alkalis (Na₂O, K₂O) that melt aggressively, MgO provides controlled, gradual fluxing action that improves melt homogeneity without excessive liquid formation. This results in better bubble elimination, smoother glaze surfaces, and more predictable body properties.

Quick Answer: Each 1% increase in MgO content across the talc grade range corresponds to approximately 2–4°C reduction in effective firing temperature. 91# (32.1% MgO) can reduce body firing temperature by 30–60°C compared to talc-free formulations; 93# (31.09% MgO) achieves similar effect with added whiteness benefit.

The MgO-to-SiO₂ ratio also affects melt viscosity. Higher MgO grades (91#) produce lower viscosity melts at a given temperature, improving glaze leveling and body densification. However, excessively low viscosity can cause glaze running or sagging on vertical surfaces.

Table 3 — MgO Flux Strength Comparison by Grade (Goway in-house testing, 2025)
Grade MgO Content Relative Fluxing Strength Estimated Firing Temp Reduction Best For
91# 32.1% Strongest (reference) 30–60°C reduction Low-temp firing, energy saving
93# 31.09% Strong 25–50°C reduction White premium bodies
88# 29.2% Moderate 20–40°C reduction Standard tiles, general use
90# 28.8% Moderate 18–35°C reduction Balanced performance

Application note: The actual firing temperature reduction depends on the complete body or glaze composition, heating rate, and kiln type. Pilot trials are recommended to establish the precise relationship for each specific formulation. (Goway in-house testing, 2025.)

Quick Selection Guide

Choose based on your primary requirement: maximum whiteness, strongest fluxing, or cost-performance balance.

Which Calcined Talc Grade Is Right for Your Application?

Ultra-White Bodies

Priority: Maximum whiteness (L* > 93)

→

High MgO / Fluxing

Priority: Lower firing temperature

→

Cost-Balance

Standard white tiles, general use

93# — Highest Whiteness (95.3%) 91# — Highest MgO (32.1%) 90# — Lowest Fe   2O  3 (0.03%) 88# — Cost-Effective Standard

Technical Review

Data verified by Goway Product Team. MgO content directly correlates with fluxing strength — higher MgO grades reduce firing temperature more effectively. Fe₂O₃ content determines color purity in oxidizing atmospheres. Whiteness target (L*) should guide grade selection for visible ceramic surfaces. (Goway in-house testing, 2025.)

Recommended Dosage of Calcined Talc in Ceramic Body and Glaze

Dosage depends on formulation goals: whiteness, fluxing strength, thermal shock resistance, or cost reduction.

Table 4 — Recommended Dosage by Application and Grade (Goway Technical Guidelines, 2025)
Application Recommended Dosage Best Grade(s) Key Consideration
Premium white body (L* > 93) 5–10% 93# (95.3% whiteness) Use lowest Fe₂O₃ grade; combine with high-purity feldspar
Standard white tile body 8–12% 90# (92.8% whiteness) Balance of whiteness, cost and fluxing
Low-temperature firing body 10–18% 91# (32.1% MgO) Monitor dry strength; add bentonite binder if needed
Thermal shock-resistant body 12–20% 91# / 88# High talc content reduces thermal expansion coefficient
Ceramic glaze (matte/satin) 5–15% 90# / 93# D90: 20–45μm; adjust for target surface finish
Economic floor tile body 8–15% 88# (cost-balance) Most cost-effective for standard applications
Processing Note

High talc additions (above 15% in bodies) may reduce dry strength and green body integrity. If adding more than 15% talc, consider supplementing with 0.2–0.5% bentonite clay or 0.1–0.3% CMC (carboxymethyl cellulose) as binder. Pre-wet the talc before mixing to reduce dust and improve dispersion. (Goway in-house testing, 2025.)

Troubleshooting: Whiteness, Fe₂O₃ and Thermal Shock

Common issues when using calcined talc in ceramic formulations and how to address them.

Whiteness Below Target (L* < Expected)

Check: Fe₂O₃ source. Even 0.1% Fe₂O₃ difference produces visible color shift in white bodies under oxidizing firing.

Action: Upgrade to 93# (0.04% Fe₂O₃) or 90# (0.03% Fe₂O₃). If budget-constrained, reduce talc addition and supplement with higher-purity whitening agents.

Test: Measure whiteness on fired tiles using CIE L* at D65 illuminant.

Excessive Body Shrinkage or Warping

Check: Raw (uncalcined) talc contamination or excessive L.O.I. in the talc source.

Action: Verify talc is properly calcined (L.O.I < 1.0%). Goway grades: 91# has lowest L.O.I (0.11%), confirming complete calcination. Reduce addition rate or increase kaolin content to compensate.

Test: Fire test bars and measure linear shrinkage at your actual firing temperature.

Thermal Shock Cracking in Fast-Firing

Check: Thermal expansion coefficient and body elasticity.

Action: Increase talc content (thermal shock resistance improves with higher talc up to 20%). Consider 91# for highest MgO ratio, or add cordierite precursors if MgO alone is insufficient.

Test: Quench test: air-cool tiles from peak firing temperature and inspect for cracks.

Detailed Product Specifications

Click each grade to expand technical details, typical applications, and processing recommendations.

Calcined Talc 93# — Ultra-White Premium Grade

93# 95.3% Whiteness 31.09% MgO Ultra-Low Fe   2O  3 (0.04%)
95.3
Whiteness
0.04
Fe   2O  3 %
0.12
Al   2O  3 %

Key Characteristics

Highest whiteness in Goway talc lineup. Ultra-low Fe₂O₃ (0.04%) and Al₂O₃ (0.12%) minimize color contamination. 31.09% MgO provides strong fluxing while maintaining structural integrity.

Benefits

Enables production of premium white ceramics with L* values exceeding 93. Reduces need for expensive whitening additives. Consistent batch-to-batch performance under strict QC standards.

Chemical Profile

MgO: 31.09% | SiO₂: 65.7% | CaO: 2.57% | Fe₂O₃: 0.04% | Al₂O₃: 0.12% | L.O.I: 0.31%

Typical Applications

  • Premium porcelain tiles (Class A whiteness, L* > 93)
  • Sanitaryware bodies requiring high L* values
  • White-glazed products where color purity is critical
  • High-value tableware and giftware ceramics

Selection Notes

  • If cost is primary concern: Consider 90# (92.8% whiteness, lower price point)
  • If highest MgO fluxing needed: Consider 91# (32.1% MgO, 90.3% whiteness)
Processing Recommendation

Recommended addition: 5–15% in ceramic bodies. For maximum whiteness, use in combination with high-purity feldspar. Firing temperature can be reduced by 20–40°C compared to standard talc grades. Maintain proper ball milling to achieve D90 below 45μm for optimal dispersion. (Goway in-house testing, 2025.)

Calcined Talc 90# — High Whiteness Grade

90# 92.8% Whiteness 28.8% MgO Lowest Fe   2O  3 (0.03%)
92.8
Whiteness
0.03
Fe   2O  3 %
0.57
L.O.I %

Key Characteristics

Excellent balance of whiteness (92.8%) and cost-performance. Lowest Fe₂O₃ content (0.03%) across all grades ensures clean color development. 28.8% MgO provides reliable fluxing effect.

Benefits

Delivers premium whiteness without premium pricing. Consistent CaO content (3.3%) provides good mineral balance in body formulations. Widely suitable for standard to premium ceramic tile production.

Chemical Profile

MgO: 28.8% | SiO₂: 65.84% | CaO: 3.3% | Fe₂O₃: 0.03% | Al₂O₃: 0.98% | L.O.I: 0.57%

Typical Applications

  • Premium ceramic tiles (Class B whiteness, L* 90–93)
  • Glossy wall tiles requiring clean base color
  • Medium-grade sanitaryware
  • Ceramic glazes as flux component (5–15% addition)

Selection Notes

  • If maximum whiteness required: Upgrade to 93# (95.3% whiteness)
  • If budget is primary concern: Consider 88# (88.8% whiteness, lower cost)
Processing Recommendation

Optimal for bodies requiring L* values of 90–93. The 3.3% CaO content complements MgO fluxing. Recommended addition in bodies: 8–12%. In glazes: 5–10%. Pre-mix with water before adding to reduce dust and improve dispersion. (Goway in-house testing, 2025.)

Calcined Talc 91# — High MgO Fluxing Grade

91# 32.1% MgO Highest Fluxing Strength 90.3% Whiteness
32.1
MgO %
0.11
L.O.I %
90.3
Whiteness

Key Characteristics

Highest MgO content (32.1%) in Goway talc lineup. Maximum fluxing strength lowers firing temperature effectively. Lowest L.O.I (0.11%) indicates complete calcination and minimal volatiles during firing.

Benefits

Strongest fluxing action reduces energy consumption and kiln cycle time. Low CaO (0.73%) and high MgO ratio provides controlled melting behavior. Suitable for bodies requiring thermal shock resistance and fast-firing cycles.

Chemical Profile

MgO: 32.1% | SiO₂: 64.71% | CaO: 0.73% | Fe₂O₃: 0.29% | Al₂O₃: 1.59% | L.O.I: 0.11%

Typical Applications

  • Low-temperature firing bodies (1100–1180°C)
  • Thermal shock-resistant ceramic bodies
  • Cordierite-containing technical ceramics
  • Fast-firing ceramic tile bodies

Selection Notes

  • If whiteness is priority: Consider 93# or 90# (both above 92% whiteness)
  • If ultra-low Fe₂O₃ needed: Consider 90# (0.03% vs 0.29%)
Processing Recommendation

Use 91# when energy cost reduction is priority. Firing temperature can be reduced by 30–60°C compared to talc-free formulations. Recommended addition: 10–18% in bodies. Monitor body plasticity as high talc content reduces dry strength — consider adding bentonite or CMC as binder if needed. (Goway in-house testing, 2025.)

Calcined Talc 88# — Balanced Cost-Performance Grade

88# Cost-Effective 29.2% MgO 0.07% Fe   2O  3
88.8
Whiteness
66.45
SiO₂ %
29.2
MgO %

Key Characteristics

Best cost-performance balance in Goway talc lineup. Ultra-low Fe₂O₃ (0.07%) ensures clean color development for standard applications. Highest SiO₂ content (66.45%) provides good structural contribution.

Benefits

Cost-effective solution for standard ceramic tile production. Reliable batch-to-batch consistency. Widely available with consistent supply chain. Good balance of fluxing (29.2% MgO) and structural properties.

Chemical Profile

MgO: 29.2% | SiO₂: 66.45% | CaO: 2.55% | Fe₂O₃: 0.07% | Al₂O₃: 0.92% | L.O.I: 0.57%

Typical Applications

  • Standard ceramic floor tiles
  • Economic wall tile bodies
  • Ceramic pigments and colorants carrier
  • General-purpose glaze formulations

Selection Notes

  • If higher whiteness needed: Upgrade to 90# or 93#
  • If maximum fluxing needed: Consider 91# (32.1% MgO)
Processing Recommendation

Standard addition rate: 8–15% in bodies. The 66.45% SiO₂ provides good alumina-silica balance in formulations. Suitable for both oxidizing and mild reducing atmospheres. Dust control measures recommended during handling due to fine particle size. (Goway in-house testing, 2025.)

Frequently Asked Questions

Technical guidance on selecting and using calcined talc in ceramic formulations.

Q What is the difference between calcined talc and raw (uncalcined) talc in ceramics?
Calcined talc has been heat-treated at 900–1050°C to remove combined water (chemically bound OH groups) and organic impurities. This process: (1) Increases chemical stability during firing, (2) Reduces body shrinkage by 2–4%, (3) Provides more consistent melting behavior in glazes, and (4) Improves thermal shock resistance. Raw talc may cause pinholes and bloating due to water release during firing.
Q How does calcined talc affect glaze melting temperature?
MgO acts as a moderate flux in ceramic glazes. Adding 5–15% calcined talc typically reduces glaze melting temperature by 30–80°C. Higher MgO grades (91# at 32.1%) provide stronger fluxing effect than lower MgO grades. This enables energy savings or use of faster firing cycles.
Q Which calcined talc grade should I choose for white-bodied tiles?
For premium white bodies (L* > 93), 93# with 95.3% whiteness and ultra-low Fe₂O₃ (0.04%) is recommended. For standard white tiles (L* 88–93), 90# at 92.8% whiteness offers excellent value. 88# provides cost-effective performance for general applications. Match your whiteness target to the appropriate Fe₂O₃ grade.
Q What is the typical dosage of calcined talc in ceramic bodies?
Typical addition rates: 5–20% depending on formulation goals. High additions (12–20%) maximize fluxing and thermal shock benefits. Low additions (5–10%) provide mild fluxing without major body property changes. Note: High talc content may reduce dry strength — add bentonite or organic binders if needed.
Q How does Fe₂O₃ content affect final ceramic color?
Fe₂O₃ contributes to yellow-brown coloration after firing. In oxidizing atmospheres: 93# (0.04% Fe₂O₃) and 90# (0.03% Fe₂O₃) produce the cleanest colors. In reducing atmospheres: Iron converts to lighter Fe²⁺, so higher Fe₂O₃ is more tolerable. For premium white bodies (L* > 93), use the lowest Fe₂O₃ grades.
Q How should calcined talc be stored and handled?
Store in dry conditions (max humidity 60%) to prevent moisture absorption. Use FIFO inventory rotation. During handling: wear dust mask (N95 minimum) due to fine particles. Pre-wet or use dust suppression systems when transferring. Shelf life: 24 months in sealed packaging when stored properly.

Download Complete Technical Package

Get TDS, SDS, and product selection guides for all four calcined talc grades. Sample requests processed within 24 hours.

Download All TDS (PDF) Request Sample Kit

Technical Consultation & Sample Request

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Direct contact:

info6@goway-china.com

Reviewed by: Goway Technical & Quality Team

Last updated: May 2026

Data source: Goway batch COA and internal ceramic application testing, 2025–2026.

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Founded in 2009, we specialize in producing and supplying ,ceramic additives and related products, committing to supplying stable, environmentally friendly,professional and ceramic materials.

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