The fineness of powder is denoted either by descriptive words (as in the case of brittle and easily-pulverizable substances), or in terms expressing the number of meshes to a linear inch in the sieve. The following degrees of fineness will prove serviceable in the preparation of dentifrices, polishing powders, etc: -

A very fine powder . . .

Should pass through a sieve having 80 or more meshes to linear inch.

=No. 80 Powder.

A fine powder.......................

Should pass through a sieve having 60 meshes to the linear inch.

=No. 60 Powder.

A moderately fine powder .

Should pass through a sieve having 50 meshes to the linear inch.

=No. 50 Powder.

A moderately coarse powder,

Should pass through a seive having 40 meshes to the linear inch.

=No. 40 Powder.

A coarse powder .

Should pass through a.

sieve having 20 meshes to the linear inch.

=No. 20 Powder.