Where a yellow or red colour is desired use yellow oxide, red oxide or quinacridone violet in preference to organic orange, yellow or reds. In small amounts these tend to fade out leaving the more light fast tinters behind and in some cases totally changing the colour. There are some new more durable organic yellows and reds now available but they are all very expensive. Bright reds and yellows tend to fade with the action of ultra violet. Avoid using similar tinters such as organic yellow and yellow oxide together or organic orange and red oxide, as one will generally do.
Some yellow colours have quite poor opacity compared to, for example, greys or pale blues.
Don't expect to provide a two-coat coverage with all colours. Cemititious surfaces, especially concrete and plasters, are alkaline. Incompletely cured concrete and plasters are even more caustic. Guidelines For Selecting a Base White Bases Used for the majority of colours, off whites through to deep shades. Oxide Bases Used for dark greens, tans, dark golds and oranges.