Q: Why can't a precipitated silica do the same job as fumed silica in a coating?

Precipitated grades carry their value in pore volume and surface chemistry — they matter, absorb oil and matte a film. They do not build the same primary-particle network. IOTA HL7150 is a hydrophilic fumed silica with 150 ± 15 m²/g BET made of nanoscale primary particles fused into branched chains. Dispersed under shear, those chains interlock into a hydrogen-bonded network that rebuilds viscosity when the shear stops. That network is what holds a vertical film at 80–120 µm and keeps pigment from packing in the drum.

Q: What does IOTA HL7150 actually deliver?

Q: Where does it fit?

• Coatings & paints — thixotropy, anti-sag on vertical surfaces, anti-settling of heavy pigments (roles the same grade plays in both solventborne and waterborne systems).

• Adhesives & sealants — slump control during cure, higher green strength.

• HTV & RTV silicone rubber — reinforcement of the elastomer network.

• Powder systems — free-flow and anti-caking aid.

Q: How much should I start with?

For rheology in coatings and sealants, formulators commonly work in the 0.5–2.5% range; reinforcement in silicone runs much higher. Exact loading depends on the resin polarity — the silanol-rich surface of a hydrophilic grade responds strongly to polar systems, so build the curve with a 0.5% step ladder before locking the formula.

Q: Does moisture in the drum hurt it?

The spec already caps it: loss on drying ≤1.5% (105 °C, 2 h) and ignition loss ≤2.0%. Keep bags sealed; the 10 kg kraft format limits exposure between uses.

FAQ

1. Is HL7150 treated or untreated? — Untreated (hydrophilic). For hydrophobic needs, see the IOTA hydrophobic fumed silica series.

1. Can it replace my current rheology additive directly? — Match the BET first: at 150 m²/g it sits mid-range; adjust dosage, not grade, before judging performance.

1. What dispersion energy does it need? — High-shear mixing to deagglomerate the chains; under-dispersed fumed silica reads as graininess, not thixotropy.

Related Product: Fumed Silica IOTA HL7150