Additional shipping charges may apply for 6kg and 10kg packs to Scottish highlands, UK islands, and Northern Ireland. There may be a few extra days for delivery of 6kg and 10kg bags.

Cab-O-Sil is the name for a range of amorphous fumed silica products made by Cabot Corporation. The molecular structure consists of nanometre droplets of amorphous silica fused into branched chains. They are characterised by high purity, low bulk density and submicron particle size. 

Cabot Cab-O-Sil® M-5 is a medium surface area fumed silica which imparts a significant increase in viscosity to liquid systems, free flow of powders and reinforcement of silicone and organic rubbers.

Cabot Cab-O-Sil® TS-720 is a medium surface area fumed silica which has been surface modified with polydimethylsiloxane. The treatment renders it extremely hydrophobic, with very different properties to untreated silica grades like M5.

Wacker Silicones N20ST is an untreated fumed silica very similar to Cabot Cab-O-Sil M5. Limited stock, economical 10kg bags only.

Cab-O-Sil M5

• Blended into sticky and poorly flowing powder systems, M5 reduces angle of repose and improves powder flow. During storage of powder systems, M5 reduces caking and blocking. It can also be added to sulphur to reduce the static and improve flow. A good starting point when formulating for these purposes is 0.5% by mass.

• Widely used to provide thickening, thixotrophic (shear-thinning), and anti-settling behavior in liquid systems. M5 is most efficient in non-polar to medium polarity systems. For more polar systems, treated fumed silicas are more effective. M5 offers the best balance of thickening efficiency and dispersibility.

• Can be used for reinforcement of silicone rubber and can be used to reinforce organic rubbers. It imparts good increase in hardness, tensile and elongation.

 Cab-O-Sil TS-720

• CAB-O-SIL TS-720 is Cabot's most hydrophobic treated fumed silica making it an excellent choice for moisture sensitive systems. Further the surface chemistry of TS-720 makes it very effective, stabile rheology control additive for polar systems.

• In epoxy adhesives and coatings, TS-720 provides good thickening efficiency, sag resistance (for film build) and anti-settling of pigments and fillers. While untreated fumed silica may also provide the similar rheology control initially, only TS-720 provides stable rheological properties over time. For applications requiring storage stability, TS-720 is recommended.

• In polyurethane adhesives and coatings, TS-720 provides the same stable rheology control as in epoxy systems. In addition, the hydrophobic surface of TS-720 introduces very little moisture into these systems, preventing premature cross-linking of moisture cured systems.

• CAB-O-SIL TS-720 is used for rheology control of vinyl ester laminating resins and bonding pastes. While untreated fumed silica are effective thickeners of unsaturated polyester resin laminating resins, gel coats, and bonding pastes, TS-720 is a more effective rheology control additive for higher polarity systems like vinyl esters.

• The hydrophobic TS-720 grade can be used in fly fishing for keeping flies dry and nail artists can use this grade to suspend glitters in clear top coats.

There are some restrictions on food, medical and cosmetic applications for the M5 grade of Cab-O-Sil®, please refer to the downloads section at the bottom of this page for more details. (Search for Inoxia's website for downloads.)

Specifications