Iron content (indicated by Fe2O3 105°C of baking) % ≥

95

 Volatile matter at 105°C % ≤

1.0

    Residue on sieve    %≤

0.3

mesh

Water extraction liquid acidity alkality  %≤

20

Phvalue of water suspension

5-7

Oil absorption

15-25

Tatal calcium content %≤

0.3

colour

Almost-micro

  Comparison of relative tinting strength  % ≥

95

Exisance organic tinting matter

Negative

Water soluble chloride and sulfate

0.2

Lead chromate

negative