Sulphate vs chloride process titanium dioxide
How the two pigment manufacturing routes differ — and why procurement should compare the finished grade, surface treatment and application trial instead of selecting on process name alone.
Neither process is an automatic quality grade.
The sulphate process dissolves titanium feedstock in sulphuric acid, hydrolyses titanyl sulphate and calcines the hydrate into anatase or rutile. The chloride process converts feedstock to titanium tetrachloride and oxidises it at high temperature, producing pigmentary rutile. Chloride grades often have a reputation for clean colour, while a well-designed sulphate rutile can meet demanding coatings, plastics and ink requirements. Buyers should approve the specific pigment, not the route label.
Spelling note: sulphate is the British spelling and sulfate is the U.S. spelling; both refer to the same production route.
What changes — and what does not.
| Factor | Sulphate process | Chloride process |
|---|---|---|
| Core intermediate | Titanyl sulphate solution followed by hydrolysis and calcination. | Purified titanium tetrachloride followed by gas-phase oxidation. |
| Crystal forms | Can produce pigmentary anatase or rutile. | Produces pigmentary rutile. |
| Feedstock flexibility | Can use a wider range of ilmenite and upgraded feedstocks. | Normally requires feed suitable for chlorination and purification. |
| Performance controls | Hydrolysis, calcination, milling and surface treatment control the final pigment. | Oxidation, particle-size control, milling and surface treatment control the final pigment. |
| Finished-grade decision | Compare TiO2 content, colour, undertone, tint strength, surface treatment, dispersion, moisture/volatiles, oil absorption, durability and application results. | |
TiO2 Source portfolio: R818, R838, R868, R878 and A1 are positioned as sulphate-process grades. A chloride-process alternative can be sourced when the buyer's approved-vendor list or performance target requires it.
When the process route matters.
Approved-vendor or origin requirement
Some global formulations specify a named chloride or sulphate grade. Treat this as a contractual requirement and qualify equivalents through change control.
Anatase requirement
If the application genuinely needs pigmentary anatase, the production route is sulphate. Review rutile vs anatase before finalising the RFQ.
Exterior coating performance
Crystal form and surface treatment matter more than the process name alone. Compare weathering, chalking, gloss retention and colour change in the actual paint.
Masterbatch processing
Moisture, organic treatment, dispersion, filter pressure, lacing and heat stability are more useful acceptance criteria than sulphate/chloride alone.
How to compare two TiO2 quotations
- Normalize grade, crystal form, surface treatment, packaging, Incoterm and delivery basis.
- Request current TDS, SDS and a recent lot COA rather than relying on catalogue process descriptions.
- Specify the buyer's analytical methods where results can vary by method.
- Run side-by-side dispersion and finished-product trials using the same addition level and process conditions.
- Evaluate total formulation cost: pigment dosage, dispersant demand, throughput, rejects, gloss, hiding and durability.
Specification boundary
A process route cannot guarantee colour, opacity, gloss, durability or plastics processing. Those are finished-grade and formulation properties. The approved specification should therefore combine measurable pigment parameters with a defined application test.
Industry and technical sources.
Industry-association background on titanium dioxide, common applications and sulphate/chloride manufacturing routes.
Independent industry reference only. TiO2 Source is not affiliated with TDMA, and no TDMA endorsement is implied.
Professional explanation of route, particle-size formation, milling, inorganic/organic treatment and their effect on performance.
Supports comparing final grade properties, dispersion and formulation performance rather than relying on production route alone.
Sulphate vs chloride questions.
Is chloride-process TiO2 always higher quality?
No. Chloride and sulphate are production routes, not universal quality levels. The correct comparison is the specific finished grade and its performance in the buyer's formulation.
Can sulphate process make rutile TiO2?
Yes. The sulphate process can make rutile or anatase pigment. The TiO2 Source R-series grades are sulphate rutile.
What should be on a process-comparison RFQ?
State whether process route is mandatory, then define crystal form, surface treatment, analytical limits, application tests, pack, volume, destination and documentation.
Can TiO2 Source supply a chloride-process alternative?
Yes, subject to the required grade, producer approval, volume and destination. Send the incumbent TDS or target specification for matching.
Compare sulphate and chloride grades on the same basis.
Send the incumbent grade, application test, required documents, volume and destination for a matched proposal.
Compare the five verified TiO₂ grade specifications.
Review crystal form, TiO₂ content, surface treatment, oil absorption, pH, tinting-method boundaries and manufacturer-listed applications in one evidence-aligned matrix.