Two 200 m²/g hydrophilic fumed silicas go head-to-head on specs, thickening performance, and total delivered cost for North American formulators.
SEMISIL 200 vs CAB-O-SIL M-5: Spec-Grade Comparison for North American Formulators
Two 200 m²/g hydrophilic fumed silicas go head-to-head on specs, thickening performance, and total delivered cost for North American formulators.
SEMISIL 200 and CAB-O-SIL M-5 are both general-purpose hydrophilic fumed silica grades manufactured via high-temperature flame hydrolysis of chlorosilanes. CAB-O-SIL M-5, produced by Cabot Corporation at facilities in Midland, MI and Tuscola, IL, has been the default 200 m²/g grade specified in North American formulations for decades. SEMISIL 200 is a direct functional equivalent manufactured by Shandong Semichen — same nominal BET surface area, same amorphous SiO₂ chemistry, same primary particle size range (7–9 nm). Both grades carry ≥99.8% SiO₂ purity on an anhydrous basis. The core difference is supply chain: SEMISIL 200 ships from Chinese production with warehousing options in US ports, offering formulators a second-source strategy that reduces single-supplier risk.
In thixotropic applications — the primary use case for both grades — performance is governed by the silanol group density on the particle surface and the resulting hydrogen-bond network. Both SEMISIL 200 and CAB-O-SIL M-5 carry approximately 2.5 silanol groups per nm², producing comparable viscosity build in epoxy systems, unsaturated polyester resins, and solvent-borne coatings. At typical loading levels of 1–3 wt%, both grades deliver structured viscosity with a shear-thinning profile that prevents sag and settling while still allowing brush or spray application. Formulators switching from M-5 to SEMISIL 200 generally find no adjustment needed in loading level — the 200 m²/g BET equivalence translates directly to equivalent thixotropic efficiency.
CAB-O-SIL M-5 currently trades at approximately $4.50–5.50/kg for pallet-scale orders delivered within the continental US. SEMISIL 200, imported with US port warehousing, typically lands at $3.50–4.50/kg at comparable volumes — a 15–25% cost reduction depending on freight lane and order size. For a compounder consuming 20 MT/year, that delta translates to $20,000–30,000 in annual raw material savings. The trade-off is lead time: Cabot offers 2–3 week domestic delivery, while SEMISIL 200 from bonded warehouse ships in 1–2 weeks, or 6–8 weeks if ordering direct from origin. Dual-sourcing both grades eliminates single-supplier risk without any reformulation cost — the specs are interchangeable at the batch level.
Both grades are produced by the same fundamental process — continuous flame hydrolysis of silicon tetrachloride (SiCl₄) in an oxy-hydrogen flame at temperatures above 1800 °C. The resulting nano-scale SiO₂ particles fuse into branched aggregates, then agglomerate into the fluffy white powder formulators handle. Process control variables — flame temperature profile, residence time, SiCl₄ feed rate — determine the final BET surface area and aggregate structure. Where CAB-O-SIL M-5 benefits from Cabot’s mature process controls refined over 60+ years of production, SEMISIL 200 matches the target 200 ± 25 m²/g window with modern automated furnace controls and continuous in-line monitoring.
| Property | SEMISIL 200 | CAB-O-SIL M-5 |
|---|---|---|
| BET Surface Area | 200 ± 25 m²/g | 200 ± 25 m²/g |
| SiO₂ Content (anhydrous) | ≥ 99.8% | ≥ 99.8% |
| Primary Particle Size | 7–9 nm | 7–9 nm |
| Tamped Bulk Density | ~50 g/L | ~50 g/L |
| pH (4% aqueous suspension) | 3.7–4.5 | 3.6–4.3 |
| Loss on Ignition (1000 °C, 2h) | ≤ 1.0% | ≤ 1.5% |
| HCl Content | ≤ 250 ppm | ≤ 250 ppm |
| Moisture (105 °C, 2h) | ≤ 1.5% | ≤ 1.5% |
The table below consolidates the critical specifications formulators need when evaluating SEMISIL 200 as an alternative…
The table below consolidates the critical specifications formulators need when evaluating SEMISIL 200 as an alternative to CAB-O-SIL M-5. All values represent typical lot data from certificate-of-analysis documentation.
| Evaluation Criterion | SEMISIL 200 | CAB-O-SIL M-5 | Verdict |
|---|---|---|---|
| BET Surface Area | 200 ± 25 m²/g | 200 ± 25 m²/g | Equivalent |
| Thickening Efficiency (epoxy, 2 wt%) | Equivalent viscosity build | Reference standard | Match |
| SiO₂ Purity | ≥ 99.8% | ≥ 99.8% | Equivalent |
| Bulk Density (tamped) | ~50 g/L | ~50 g/L | Equivalent |
| Trace HCl | ≤ 250 ppm | ≤ 250 ppm | Equivalent |
| Delivered Price (US, pallet) | $3.50–4.50/kg | $4.50–5.50/kg | SEMISIL 15–25% lower |
| Domestic Lead Time | 1–2 wk (warehouse) | 2–3 wk | Comparable |
| FDA/EU food-contact compliance | Available on request | Established dossier | Cabot advantage |
SEMISIL 200 matches CAB-O-SIL M-5 on every critical specification — BET, purity, particle size, and thickening efficiency — while offering 15–25% lower delivered cost. For North American formulators already qualified on M-5, switching or dual-sourcing requires no reformulation.
Yes, SEMISIL 200 is a direct drop-in replacement for CAB-O-SIL M-5 in virtually all applications. Both grades share 200 m²/g BET surface area, ≥99.8% SiO₂ purity, and 7–9 nm primary particle size. Most formulators require no loading adjustment when switching between the two grades.
Typical savings range from 15–25% on delivered cost depending on volume and freight lane. At pallet-scale US delivery, SEMISIL 200 lands at approximately $3.50–4.50/kg versus $4.50–5.50/kg for CAB-O-SIL M-5. A 20 MT/year compounder can save $20,000–30,000 annually.
A basic qualification involves viscosity-build comparison at your standard loading level (typically 1–3 wt%) plus 72-hour accelerated storage stability testing at 50 °C. If both metrics match your existing CAB-O-SIL M-5 baseline within specification limits, the switch is validated.
SEMISIL 200 delivers equivalent reinforcement to CAB-O-SIL M-5 in HTV silicone compounds. At 15–25 phr loading, both grades provide 6–8 MPa tensile strength improvement. The identical BET surface area and silanol density ensure comparable filler-polymer interaction.
SEMISIL 200 ships from US-based bonded warehouses in 1–2 weeks, comparable to Cabot’s 2–3 week domestic delivery. Direct-from-origin orders require 6–8 weeks. Maintaining buffer stock at a US warehouse eliminates the ocean freight lead time entirely.
Chinese-origin fumed silica may be subject to Section 301 tariffs depending on the current HTS classification for synthetic amorphous silica. Formulators should consult their customs broker for the applicable duty rate and factor it into the landed cost comparison before committing to volume.
Get Samples & TDS
Free samples for qualified buyers · reply within 24h. Tell us how you plan to use Semisil 200 Vs Cab O Sil M5.