How do I maximize my Duotones?

[Crimson]

Duotines are good for making things 2 color to save cost or time on a press.
However, I can't figure them out totally. If I pic red and blue I get a mixture that makes a purple picture. However, if I want to use red or Blue, photoshop can only get a shade of Purple. Then if I play with the curves on each color I can get Red and blue but lose my whites. I want to be able to utilize my duotones so that ink is 2 color and the color of the paper becomes a third.

I tried a Tritone suggested by Printdriver and made the 3rd color white but then it won't save the spot colors which kind of defeats the point for seperations. I tried it as a duotone and created a spot color channel and it worked but it won't export the spot colors either. Any other suggestions?

[Mynock]

we used Powertone (http://www.adobe.com/products/plugins/photoshop/faq/powertonefaq.html) which is a plug-in for Photoshop, when I worked at the quick printer. We only have one job that we regularly used it on, and that was a newsletter. Which the cost of digital color coming down more people opt for that, and it's alot less hassle. Powetone has alot of little quirks you have to figure out, but once you do it works fairly well.