Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Silica Flour and Silica Fume
Name: Mark
Status: other
Grade: other
Location: NV

What is the difference between silica flour and silica fume?

Hi Mark,

Both materials are pure silica (silicon dioxide). Silica flour is simply made by grinding pure silica sand to a very fine powder. It is used as a cheap filler in plaster and some plastics to add strength, or just to reduce the amount of (expensive) resin needed to fill a mold.

Fumed silica is made in a very unusual way, by reacting silicon tetrachloride in an oxy-hydrogen flame that has an excess of oxygen. A very light, fluffy, pourable solid results. Fascinating stuff, actually! Fumed silica is mainly used as a thixotropic additive to plastic resins and other liquids. For example, when added to an epoxy resin, the resin will not "run" when left to stand, but will still pour if it is agitated. Both forms of silica are essentially inert.

Bob Wilson.

Click here to return to the Material Science Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory