Reviewed by Er. Manoj Kumar — Founder & Chief Formulator · 15+ years lubricant & grease R&D
The newest and most technologically advanced soap grease chemistry — calcium sulfonate complex (CaSX) uses overbased calcium sulfonate concentrate as the structuring agent, converted in situ from amorphous calcite to crystalline vaterite morphology to form the grease gel. The chemistry delivers inherent extreme pressure performance, outstanding rust protection, water washout below 1%, and no true drop point — all in a single thickener without external EP additives. This guide covers the gel-conversion SOP, raw-material specifications, NLGI grade range, ASTM performance targets, and the reactor capability for premium-tier production.
>300°C
No Drop Point Observed
NLGI 1–2
Consistency Range
25–35%
Sulfonate Loading
Inherent EP
No External EP Needed
Chemistry Overview
What Calcium Sulfonate Complex Grease Actually Is
CaSX grease is fundamentally different from soap-thickened greases. Where lithium and calcium soap greases rely on long fibres of saponified fatty acid to trap base oil, CaSX uses crystalline calcium carbonate as the structuring agent — specifically, calcium carbonate in the vaterite crystal morphology, dispersed inside calcium sulfonate micelles.
The starting raw material is overbased calcium sulfonate concentrate (typically TBN 350–400 mg KOH/g, ~40% active material in mineral oil) — the same overbased detergent used in engine oils. Inside this concentrate, surplus calcium beyond the stoichiometric sulfonate is held as amorphous calcium carbonate (calcite) inside surfactant micelles. In CaSX manufacturing, a conversion process — involving a facial acid (12-HSA or stearic), a promoter alcohol (n-hexanol or isopropanol), water, and a calcium hydroxide top-up — transforms this amorphous calcite into the crystalline vaterite polymorph of CaCO₃. The vaterite particles, supported by the surrounding sulfonate surfactant, inter-lock to form a three-dimensional gel structure that thickens the oil.
The performance consequences are striking. Because the structuring agent is calcium carbonate, which does not melt but decomposes only above 800°C, the grease has no true drop point — in ASTM D2265 testing, the result is typically "no drop observed at 300°C". Because the sulfonate surfactant component is itself an EP additive (the same chemistry used in industrial gear oil EP packages), the grease has inherent four-ball weld points of 315–500 kgf without any added EP. Because calcium carbonate is hydrophobic and the sulfonate is highly oleophilic, water washout per D1264 is typically 1–3% — the best of any soap-thickened chemistry. The trade-off is cost: the raw material is expensive, 25–35 wt% sulfonate loading is required, and the conversion process is sensitive to control. CaSX sits alongside the other premium complex soaps such as barium complex grease manufacturing and aluminium complex grease manufacturing in our high-performance range.
Raw Materials
Raw Material Specifications & Suggested Treat Rates
Component group
Typical role
Typical share
Overbased calcium sulfonate
Structuring thickener, TBN 350–400 concentrate
25–35 wt%
Base oil
Carrier fluid
Balance
Conversion charge
12-HSA or stearic acid, promoter alcohol, water, calcium hydroxide — amorphous calcite to vaterite
Process charge
Optional EP top-treat
Sulfurised olefin when a steel-mill weld above 500 kgf is required
0–2 wt%
High-level composition already described on this page. ASTM D2265 is typically reported as no drop at 300°C, four-ball weld is typically 315–500 kgf without added EP, and D1264 water washout is typically 1–3%. Exact components and supplier names are shared under NDA.
Manufacturing SOP
Gel Conversion Process — 6 Steps, Controlled Exotherm
CaSX manufacturing is not a saponification — it is a controlled phase-conversion of an amorphous solid to a crystalline polymorph inside a colloidal carrier. The chemistry is sensitive and the conversion exotherm requires careful temperature control. The following SOP is for a typical 200–500 kg batch in a stainless-steel jacketed reactor. Total cycle time is approximately 8–10 hours.
1
Charge overbased sulfonate and base oil (T = 60–70°C)
Charge the overbased calcium sulfonate concentrate and the base oil (Group II SN500 + SN150 blend) into the jacketed reactor. Heat to 60–70°C with anchor stirrer at 30–60 rpm. Hold 15 minutes after the mass is homogeneously dispersed — the bulk should appear as a clear amber to dark amber liquid at this stage, lower viscosity than the original sulfonate concentrate.
2
Conversion promoter addition (T = 70–80°C)
Add the conversion promoter package in sequence: facial acid (12-HSA, pre-melted in a small amount of base oil), then promoter alcohol (n-hexanol or IPA), then water (slowly — rapid water addition can cause local conversion and inhomogeneous gel), then calcium hydroxide slurry. Stir 15 minutes at 70–80°C for homogeneous mixing. The bulk should remain a clear amber liquid — no gel formation yet at this temperature.
3
Gel conversion exotherm (T = 90–110°C, 60–90 min)
Raise temperature slowly to 90–95°C using jacket steam at moderate rate. The conversion initiates near 90°C and is exothermic — bulk temperature self-rises 15–20°C above jacket setpoint over 10–15 minutes. Have jacket cooling water on standby. The amorphous calcium carbonate inside the sulfonate micelles converts to crystalline vaterite. Bulk viscosity rises dramatically (typically 10× or more) over 20–30 minutes as the gel structure forms. Stirrer torque rises sharply — verify the drive can handle the load. Hold at 105–110°C for 30 minutes to complete conversion.
4
Dehydration and structure consolidation (T = 150–180°C, 30 min hold)
Open vent. Ramp temperature from 110°C to 150–180°C over 30 minutes. Water and promoter alcohol evolve. Hold at 180°C for 30 minutes to fully drive off volatiles and consolidate the vaterite gel structure. Verify water content of a sample is below 0.5%. The grease at this stage has its final structure but no service additives.
5
Cool-down and additive addition (T = 180°C → 90°C over 60 min)
Cool to 90°C using jacket water at moderate flow. CaSX does not require the slow controlled cool of lithium soap (the structure is already established and is not melt-recrystallised) — 60 minutes is adequate. At 90°C add supplementary additives: EP top-up (optional, sulfurised olefin 1–2%), antioxidant, optional rust inhibitor top-up. Stir 20 minutes to fully disperse.
6
Milling and packaging (T = 60–70°C)
Cool to 60–70°C and discharge through a coarse screen. Pass through three-roll mill or homogeniser 2–3 passes (gap 50/25/25 µm). Milling consolidates the vaterite gel and develops final consistency. Test ASTM D217 worked penetration, D2265 drop point (typically >300°C / no drop observed), D1264 water washout, D2783 four-ball weld. Pack into clean drums when in spec.
NLGI 1/2 CaSX for marine stern tube bearings, deck cranes, anchor windlasses, mooring winches — severe salt water exposure, slow speed, high load. Water washout <3% and salt spray pass make CaSX the standard marine premium chemistry.
Salt water
STEEL MILL
Roll Neck & Continuous Casting
NLGI 1/2 CaSX for hot-strip mill roll neck bearings, continuous casting mould oscillator bearings — very high EP, water quench resistance, no-drop-point thermal margin. Premium alternative to LiX where the customer specifies CaSX.
No drop point
PAPER MILL
Wet End & Press Section Bearings
NLGI 2 CaSX for paper machine wet-end and press-section bearings — continuous water exposure (90–100% humidity), 60–120°C temperature, large radial load. CaSX is the dominant chemistry in modern paper-mill lubrication.
High humidity
MINING
Drag Lines & Shovel Bearings
NLGI 2 CaSX for mining shovel bearings, drag-line bucket pins, crusher bearings — shock load, dust ingress, rain exposure. Inherent EP >400 kgf without external additive simplifies the formulation and improves bearing life.
Heavy mining
FOOD GRADE
NSF H1 CaSX Variant
NSF H1 CaSX is available using HX-1 listed overbased calcium sulfonate and USP white oil base. Combines premium performance with food-contact compliance — preferred for high-load food processing bearings, dairy filler bearings.
HX-1 compliant
CEMENT
Kiln Trunnion & Crusher Bearings
NLGI 1/2 CaSX for cement kiln support roller bearings — continuous high temperature (140–180°C bearing bulk), large bearing diameter (often >1 m), very long relubrication intervals. The no-drop-point thermal margin and oxidation stability suit the application.
Continuous high temp
Failure Modes
Common Failure Modes & Production Fixes
Failure Mode
Root Cause
Diagnostic Test
Fix
Conversion does not initiate; mass stays liquid
Promoter package incomplete; water content too low; sulfonate concentrate TBN too low
Bulk viscosity; sulfonate TBN; water content
Verify promoter alcohol 1–2%, water 0.5–1.5%, facial acid 1.5–3%; verify TBN 350+ on incoming sulfonate; warm reactor to 100°C and add more promoter
Runaway exotherm; bulk overshoots 130°C
Heat-up rate too fast; cooling not on standby; agitation inadequate to dissipate heat
Reactor temperature log
Slow ramp rate into conversion zone; have cooling jacket water on standby below 95°C; verify stirrer baffle design
Grease soft / no gel structure
Conversion incomplete (held at too low temperature); or facial acid dose too low
D217 penetration; conversion temperature log
Re-process: raise temperature to 105–110°C and hold 30 min; verify facial acid 1.5–3% of total batch
Grease grainy / gritty texture
Inhomogeneous conversion — local hot spots converted before bulk; agitation poor
Microscope; sensory check
Improve stirrer design (anchor + frame); slower temperature ramp; ensure pre-mixing before conversion temperature
Water washout above 5%
Promoter water/alcohol not fully driven off; or sulfonate-to-base-oil ratio too low
D1264; water content; FTIR
Extend dehydration hold to 60 min at 180°C; verify sulfonate loading 25%+ of total batch
Drop point reported <300°C
Test artefact — oil bleed at high temperature, not gel collapse; or sulfonate loading too low
D2265 retest; verify oil separation
Increase sulfonate loading; reduce free oil content; CaSX typically reports as 'no drop observed at 300°C'
Stirrer drive trips during conversion
Viscosity rise during conversion exceeds drive capacity
Stirrer torque log
Specify variable-frequency drive sized for 3× the base oil viscosity load; reduce stirrer speed during conversion peak
Plant Equipment
Pilot & Production Plant Equipment for CaSX
A CaSX plant requires more specific reactor capability than a lithium plant: 304 or 316 stainless steel construction (preferred over mild steel due to potential mild corrosion from overbased sulfonate and conversion intermediates), oversized stirrer drive to handle the viscosity rise during conversion, and rapid cooling capacity for exotherm management. See our Plant Setup service for complete specification, layout and commissioning.
A jacketed reactor 400–800 L volume in 304 or 316 stainless steel (some manufacturers use glass-lined for the most premium product) rated for 220°C operation. Heating preferably by thermal oil (HTM up to 220°C) or steam (max 220°C requires high-pressure steam). Anchor stirrer with frame agitator, variable-frequency drive, oversized to handle the 10× viscosity rise during conversion — specify drive at 3× the base oil viscosity load. Jacket sized for both heating AND rapid switchover to cooling for exotherm control. Sealed head with vent for promoter alcohol and water evolution and recovery (alcohol recovery is recommended for environmental and cost reasons).
A three-roll mill (locally fabricated 2–3 TPH, 12–18 lakh (~US$14k–21k)) or high-pressure homogeniser 300 bar (10–15 lakh (~US$12k–18k) imported). Dedicated promoter pre-mix vessel (50–100 L stainless). Solvent recovery condenser on the reactor vent for n-hexanol or IPA capture. Lab equipment: high-temperature drop-point apparatus (D2265 to 320°C+), four-ball EP rig, Emcor rust tester (D6138), salt spray chamber (B117), penetrometer. Total plant capex band ₹1–3 crore (~US$118k–354k) for 300–800 kg/batch — significantly higher than equivalent lithium plant due to material grade and lab requirements. For a full breakdown across thickener routes, see our grease plant setup cost guide.
Reactor
400–800 L stainless, 220°C, oversized drive
Heating
Thermal oil with rapid cooling switchover
Lab
Emcor, salt spray, four-ball EP required
Capex band
₹1–3 cr (~US$118k–354k) pilot to production
Questions & Answers
Frequently Asked About CaSX Grease Manufacturing
What is the conversion process in CaSX manufacturing?
Overbased calcium sulfonate concentrate contains amorphous calcium carbonate (calcite) particles dispersed inside calcium sulfonate micelles. CaSX manufacturing converts these particles from amorphous calcite to crystalline vaterite morphology — a polymorph of CaCO₃ with a different crystal habit.
The vaterite particles inter-lock to form the grease gel structure. Without this conversion, the overbased sulfonate is just a liquid additive (the same chemistry sold for engine-oil EP packages). The conversion uses a facial acid + promoter alcohol + water + calcium hydroxide system at controlled temperature.
Why does CaSX have no true drop point?
The vaterite crystalline calcium carbonate that gives CaSX its structure does not melt — calcium carbonate decomposes at ~825°C without a melting transition. The grease therefore has no defined drop point — it does not flow off the test cup even at 300°C. In ASTM D2265 testing the result is typically reported as 'no drop observed at 300°C' or simply '>300°C'. This is the same reason bentone (clay) grease has no drop point.
Why is CaSX more expensive than LiX?
The base raw material — overbased calcium sulfonate concentrate (TBN 350–400) — is significantly more expensive than 12-HSA + LiOH for an equivalent NLGI 2 grease. The conversion process also requires 25–35 wt% sulfonate (vs 9–13% LiX soap) and tight process control to manage the exotherm. Raw-material cost differential is typically 50–80% higher than LiX; finished product market price differential is typically 70–120% premium — justified by the inherent EP/RP performance and no-drop-point thermal margin.
Is the CaSX exotherm dangerous?
It requires careful control but is not inherently dangerous in a properly engineered reactor. The conversion exotherm raises bulk temperature 15–20°C above jacket setpoint over 10–15 minutes. With slow temperature ramp into the conversion zone, jacket cooling on standby, and proper agitation, the reaction is fully controllable. A reactor without cooling capability or with inadequate stirring is the risk — not the chemistry itself. We provide the full safety protocol as part of the SOP.
What reactor material is needed for CaSX?
304 or 316 stainless steel is standard. The active calcium sulfonate and overbased calcium carbonate can be mildly corrosive to mild steel over multiple batches — and CaSX is sold as a premium product, so corrosion artefacts in the grease are unacceptable. Some manufacturers use glass-lined reactors for CaSX to absolutely eliminate metal pickup, especially for export to specific OEM specs.
Is CaSX inherently EP or does it need an additive?
Inherently EP — the overbased calcium sulfonate structure provides four-ball weld points typically 315–400 kgf without any added EP additive, plus excellent rust protection (D1743 pass) and water resistance. A small EP top-up (sulfurised olefin 1–2%) is sometimes added for the most demanding steel-mill specs to push weld point above 500 kgf, but the base chemistry is already EP-capable — drawn from our grease additive package range. The structuring raw material is itself an overbased calcium sulfonate detergent, the same chemistry used in engine-oil detergency. This makes CaSX uniquely simple from an additive standpoint.
What is the water washout for CaSX?
ASTM D1264 water washout at 79°C is typically 1–3% for CaSX — outstanding, the best of any soap-thickened grease. This makes CaSX the preferred chemistry for marine, paper-mill wet-end, mining and any application with severe water exposure where competing chemistries (lithium complex, calcium complex) wash out unacceptably. The hydrophobic vaterite crystals and oleophilic sulfonate surfactant combine to give a structure that simply does not interact with water.
Is CaSX compatible with other grease chemistries?
CaSX is one of the most universally compatible grease chemistries — generally compatible with lithium soap, lithium complex, calcium soap, calcium complex, and most polyurea greases. ASTM D6185 compatibility testing is recommended before mixing in critical equipment, but in practice CaSX is the chemistry of choice when switching from an unknown legacy grease because the compatibility risk is minimised. See our testing service for compatibility evaluation.
We use necessary cookies to send an enquiry. Analytics records pages and company-level network data, and may load Apollo visitor tracking, until you choose Necessary only. Enquiry replies do not require analytics. Privacy policy
WhatsApp us
Allow ChatGPT ad measurement?
With your permission, the OpenAI Pixel measures enquiries from our ChatGPT ads and may match them using securely hashed contact information. Your enquiry works with either choice. OpenAI conversion terms.
Mira · live
Brief this project
No search needed — leave a short note and the formulator picks it up.