Primrose chrome

Chrome yellow pigment (primrose chrome and permanent yellow) n. Any pigment based on normal lead chromate, PbCr04 that is characterized by a medium yellow color. Other shades ranging from light greenish-yellow to medium reddish-yellow... 

Primrose chrome n. Complex, primrose-colored chromates to with the formula PbCr04-4PbS04-Al2(0H)g has been given. See chrome-yellow pigment. 

Primrose chrome This is a pale, greenish-yellow pigment with a metastable orthorhombic crystal structure containing a solid solution of lead chromate and lead sulfate. The crystals are normally stabilized by additives. Due to a less-stable crystal form, they have poorer fastness properties compared to other monoclinic chrome pigments. 

Heaton (1928) lists primrose chrome as a current term when he was writing, stating it to be a very pale tint of Chrome (that is, a pale lead chromate). 

Primrose chrome (greenish-yellow lead sulfochromate)... 

Primrose Lemon Medium Molybdate orange Chrome orange... 

Lead Chromates and Molybdates. The lead chromates appear in several shades of yellow. The primrose and lemon are solid solutions of lead sulfate in the chromate and have the stable monoclinic stmcture. The medium shade contains no sulfate. Chrome orange is a compound with lead oxide (PbCrO TbO). Molybdate orange is a combination of lead chromate and sulfate with molybdate (PbMoO ). These pigments have the advantages of... 

Lead chromate occurs in nature as crocoite, an orange-red mineral. Synthetically prepared lead chromate and its solid solutions with lead sulfate and lead molybdate represent a hue range from primrose yellow to red. The various hues of chrome yellow, chrome orange, and molybdate orange depend not only on composition but also on crystal structure and particle size. 

Five chemical compositions constitute these pigment classes. Medium chrome yellow is essentially PbCr04 and is the reddest hue of yellow. Solid solutions of PbCr04 with PbS04 in varying proportions yield primrose and lemon chrome yellows. Their hue difference is also attributable to the their polymorphic nature— primrose yellow is orthorhombic in crystal structure and lemon yellow is monoclinic. The less stable orthorhombic crystal is treated during primrose yellow manufacture to minimize hue shifts and conversion. 

Primrose Yellow (%) Lemon Yellow (%) Medium Yellow (%) Molybdate Orange (%) Chrome Orange (%)... 

Precipitation conditions determine crystal structure. Lemon chrome yellows are precipitated hot with excess lead to form the monclinic crystal. Primrose yellow is preciptated at a lower temperature to form the orthorhombic crystal. Chrome oranges are precipitated under alkaline conditions. The higher the alkalinity, the larger the particle. The precipitation of molybdate orange is complicated by the polymorphic nature of two of the components of the solid solution precipitate lead chromate and lead sulfate. As with primrose yellow, the crystal is stabilized after precipitation to prevent conversion. 

Acetate chromes n. Lead chromate pigments prepared from lead acetate or basic lead acetate. Available as the lemon, primrose, medium, and orange shades. Kirk-Othmer encyclopedia of chemical technology pigments-powders. John Wiley and Sons, New York, 1996. Solomon DH, Hawthorne DG (1991) Chemistry of pigments and fillers. Krieger Publishing Co., New York. 

Cologne yellow See chrome yellow and light and primrose. 

Golden chrome See chrome yellow, light, and primrose. 

Lemon chrome This is a greenish-yellow pigment (slightly redder than primrose) with a monoclinic crystal structure, which is more stable compared to other crystal forms. The undertone is dependent on the lead sulfate content - the more sulfate, the greener the shade. 

Cologne Yellow See Chrome Yellow and Chrome Yellow, Light and Primrose. 

Heaton (1928) lists chrome primrose as a then current term for a chromate and sulphate of lead . 

Lead chromate sulfate is Usted by the Colour Index (1971) as Cl Pigment Yellow 34 (Cl 77603) and as a component of Cl Pigment Green 13, 15 and Cl Pigment Orange 21 (Cl 77601). Heaton (1928) also lists chrome primrose as a then-current term for a chromate and sulphate of lead . 

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