Help! Red oil paint not opaque enough...

[Marvin Mattelson]

Try painting the under-layer with an opaque earth red such as indian red or venetian red. You can then use your regular colors over it. You might even find you don't require the extra punch that cadmiums offer.

Alizarin and perm rose are very transparent pigments and so is your medium containing varnish. I don't know if there is a brand that can overcompensate for those choices. I use Michael Harding paints which I feel are far superior to any other brand I've tried.

[Peggy Baumgaertner]

You can add opacity to your cad reds by adding yellow ochre or gold ochre in the appropriate value. Interestingly, you can add up to 50% yellow ochre into cadmium red, and still have it read "cad red."

Unlike adding titanium white, adding yellow ochre will not change the value or temperature of the cad red. Marvin and Sharon are right, Aliz and Perm Rose are both transparent. Stick with at least the semi-opaque reds, like the cads.