In recent years PY74 has become the standard mid yellow arylide color. The names azo and arylide are often used for a wide range of closely related lake pigments. They form the backbone of the modern high performance organic pigment industry. Without these colors then cars and plastics would be available in only a limited number of colors and artists would have far fewer choices than we do now. Yellow Mid Azo is a slightly greener shade than Cadmium Yellow Medium but it is fairly close to the Cadmium color. So why have two pigments so nearly the same? There are three reasons - money, transparency and clarity of color.
Sometimes an artist needs this color but the budget is small and Yellow Mid Azo is considerably less costly cheaper than the Cadmium alternative. It is still an excellent pigment and is classed as ASTM I in terms of permanence and yet achieves that a at an affordable cost. That is very important for many artists.
The second reason for using this color instead of Cadmium Yellow Medium is its greater transparency. Sometimes being Opaque and having good covering power is needed and sometimes transparent effects are to be preferred. The color also has greater tinting strength than the Cadmium and is generally a cleaner color which leads to the third reason for using it. It is more suitable for making very brilliant and clean colors when used in mixtures.