Fumed Silica vs Precipitated Silica: Which to Choose?
Both fumed and precipitated silica reinforce silicone rubber and thicken sealants, but differ in surface chemistry, cost, and processing behaviour.
| Spec | ZEMSIL FS-200 | ZEMSIL FH-200D | ZEMSIL PS-165 | ZEMSIL PS-175 | ZEMSIL PS-SK |
|---|---|---|---|---|---|
| Type | Fumed, hydrophilic | Fumed, hydrophobic | Precipitated, hydrophilic | Precipitated, hydrophilic | Pre-silanized precipitated |
| Manufacturing | Pyrogenic | Pyrogenic + DMCS | Wet chemistry | Wet chemistry | Wet + bis-silane |
| BET SA (m²/g) | ~200 | ~110 | ~165 | ~175 | ~165 |
| Surface | Hydrophilic | Hydrophobic | Hydrophilic | Hydrophilic | Hydrophobic (silanized) |
| Cost tier | High | High | Low–medium | Low–medium | Medium |
| Best for | RTV, thixotropy, TS silicone | Silicone rubber, coatings | Rubber reinforcement, tires | General rubber, plastics | Green tire (one-step mixing) |
How to choose
- ▸Choose fumed silica for high-purity silicone rubber, RTV sealants, and thixotropic control.
- ▸Choose hydrophobic fumed silica (FH) when moisture resistance or easy dispersion in silicone is required.
- ▸Choose precipitated silica for cost-sensitive rubber compounding, standard tires, and plastics reinforcement.
- ▸Choose PS-SK (pre-silanized) to eliminate the separate silane-addition step in tire compounding.
Products compared
ZEMSIL FS-200
Fumed Silica (Hydrophilic)
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ZEMSIL FH-200D
Fumed Silica (Hydrophobic, DMDCS-treated)
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ZEMSIL PS-165
Precipitated Silica (Tire Grade)
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ZEMSIL PS-175
Precipitated Silica (Highly Dispersible)
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ZEMSIL PS-SK
Pre-Silanized Precipitated Silica (One-Step Tire Grade)
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