Diatomaceous earth (DE) or Kieselguhr

DE is made from a sedimentary rock composed of the skeletons of diatoms (microscopic algae) that lived 60 -100million years ago. The most important deposits of Kieselguhr are in Santa Barbara, California. Fine and coarser grades can be specified.
Note: DE is a health hazard, and inhalation of this material should be avoided. Always use appropriate PPE when filtering.

Perlite

This is produced from a vitreous rock of volcanic origin (like pumice), and looks like fragments of hollow spheres under the microscope. Perlite is coarser than most grades of DE, and is used for musts and cloudy wines. It is more abrasive to pumps and metal pipes than DE.

Cellulose

Cellulose is the basic component of all cell walls. It is prepared from pine, birch or beech wood which is powdered, chemically purified, washed and dried, and then mechanically broken down to different grades. It can be used as a powder or in pads. The cellulose used in filtration is relatively pure, but it will give a papery taste to the wine unless rinsed through with 1% citric acid first.