Cab-O-SIl Filler

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$12.90 to $165.48Each
Cab-O-Sil is a lightweight fumed silica thickener used to reduce the flow of epoxies and prevent run-off and sags on vertical or over-head surfaces.
Status: Active



Cab-O-Sil is a lightweight fumed silica thickening powder that when mixed with resin, creates a thixotropic resin, without increasing its viscosity. The reduced flow of the resin prevents run-off and sags when working on vertical or over-head surfaces. Cab-O-Sil increases the hardness of resin and produces hard, solid parts. Making it ideal for structural bonding, filling and filleting.

Can be used in conjunction with other fillers such as Chopped Fiberglass or Milled Fiberglass for added strength. Cab-O-Sil also acts as a free flow additive of powders and can be used as a reinforcing filler in silicone or organic rubbers.

  • Increase hardness of resin
  • Resin Thickener
  • Reduces flow and Controls sag
  • Acts as a free flow additive
  • Reinforcement of silicone and organic rubbers
Uses Include
  • Filling Cracks / Joints
  • Filleting putty
  • Structural Bonding


Typical General Properties
SiO2-content 1):
loss on ignition 2) at 1000 °C / 2h:
density of SiO2:
2200 g/l
refractive index:
silanol group density:
2 SiOH/nm2
electric resistivity (density 40 g/l):
>10 ^13 [Ω cm]
Physical-chemical Properties
BET-surface area:
170 - 230 m2/g
pH, in 4 % aqueous dispersion:
3.8 – 4.3
tamped density:
ca. 40 g/l
loss on drying 3) (2 h at 105°C):
< 1.5 %
sieve residue, acc. to Mocker > 40 μm:
< 0.04 %

Please note: All data to be used as a guide only; not a specification. 1) based on the substance heated at 1000 °C for 2 h 2) based on the substance dried at 105 °C for 2 h 3) ex works

Data Sheets
  • Epoxy Resins
  • Vinyl Ester Resins
  • Polyester Resins


  • General Use: Mix ratio is 1:2 (filler to resin by volume)
  • Reduce runs/sagging: Mix ratio is 1:3 (filler to resin by volume)
  • Add filler after adding catalyst to resin.
  • Fillers can affect the pot life of a resin, create a small trial batch first to determine how much working time you’ll have.
  • Silica-filled resins may be difficult to sand. Consider using Microspheres for areas that require sanding.

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