Fumed Silica Filler Powder

Silica is an agent which is used to control the thixotropy or ‘sag’ characteristics of a resin system. By adding colloidal silica powder in varying amounts to a resin mix the handling and flow characteristics can be controlled. Relatively small quantities added to a resin mix containing glass bubbles or micro balloons will give non-sag properties and impart easier handling. Silica is also used with microfibres to produce a mix suitable for use as a high strength, non-sagging structural adhesive, particularly for non-absorbent materials such as grp. The inclusion of colloidal silica has the effect of increasing the hardness of the resulting mix which will create more difficulty when sanding. For this reason silica is usually added in the minimum quantities to any mix for which sanding is anticipated. In some applications this feature can be used to an advantage, for example to create a hard wearing edge or surface.

Product Details

B.E.T. Surface Area 200 m2/g
pH (4% aqueous slurry) 3.7–4.3
325 Mesh Residue (44 microns) 0.02% max.
Bulk Density* 3.0 lb/ft3 max.
(Pour Density) (50 g/l Tap Density)
Loss on Heating* < 1.5% max.
Loss on Ignition* (@ 1000ºC) < 2 wt. %
Specific Gravity 2.2 g/cm3
Wt. per gallon 18.3 lb
Refractive Index 1.46
X-ray Form Amorphous
Assay (% SiO2) > 99.8
Oil Adsorption ~350 g/100 g oil
Average Particle (Aggregate) Length 0.2–0.3 microns