I've been reading Friedman's 'History of Color Photography' and there's a chapter devoted to Chemical Toning. It's all about changing a b&w silver image into a color image, either for 2 or 3 color subtractive prints. The chemistry seems to be relatively straightforward, and the ability to use commercially available b&w film would be a boon. Is this toning only different in degree to techniques like selenium toning, gold toning, etc? What I'd like to do is take 4x5" separation negatives (or positives I guess :confused and tone them appropriately so that I have the 3 layers of a full color print, but loose. Not only would this be a neat thing to mess around with (color balance manipulability on par w/ DT & carbro), but it would be an excellent demonstration tool for teaching about color synthesis. Imagine registering the separations in front of a classroom of kids and seeing the full color image POP into place! Now, this book is from the 40's so I'm sure a lot has been learned since then and perhaps even commercially available products exist/existed in the interim. For instance, I found this "Edwal Green Toner" (eBay #120590834111) that looks intriguing. Obviously, green wouldn't be of any use in a subtractive system, but do similar products exist? So, I'm soliciting any thoughts or suggestions. I've got more reading to do, but I'm just wanting to put out my feelers and see what anyone might know about this topic. Thanks guys & gals!