The systematic name of C.I. Pigment Yellow 42 is Bayferrox 920. With the CAS registry number 51274-00-1, it is also named as Ferric oxide Yellow. The product's categories are Inorganic & Organic Chemicals; UVCBs-inorganic, and the other registry numbers are 105478-30-6; 12000-32-7; 12001-03-5; 131462-81-2; 1342-51-4; 147625-38-5; 182761-12-2; 185464-57-7; 50641-37-7; 51109-85-4; 53028-10-7; 94809-98-0; 99241-66-4. Besides, it is lemon yellow to brown powder, which should be  sealed in an ventilated, dry warehouse. In addition, its molecular formula is Fe₂O₃^.H₂O and molecular weight is 177.71.

Preparation of C.I. Pigment Yellow 42: first, you can use Sulfuric acid to react with iron to get Ferrous sulfate. Then add concentrated sulfuric acid and sodium chlorate to produce Ferric sulfate by oxidation. Afterwards, add Ferric sulfate to the solution of Sodium hydroxide. And then you can add Ferrous sulfate and iron. At last, you would obtain this chemical after surface treatment, washing, filtrating, drying.
Fe+H₂SO₄→FeSO₄+H₂↑
6FeSO₄+NaClO₃+3H₂SO₄→3Fe₂(SO₄)₃+NaCl+3H₂O
Fe₂(SO₄)₃+6NaOH→2Fe(OH)₃+3Na₂SO₄
3Fe(OH)₃→Fe₂O₃.H₂O+2H₂O

Uses of C.I. Pigment Yellow 42: this product is used for coloring of manu-marble and waterstone in the construction industry. It is also used as pigment of watercolors, greasepaint, paint and rubber. Moreover, it can be used as an intermediate for the manufacture of iron oxide red, iron black and so on.

When you are using this chemical, please be cautious about it as the following: it is irritating to eyes, respiratory system and skin. In case of contact with eyes, please rinse immediately with plenty of water and seek medical advice.