I just got a box of ilford cold tone fiber paper and did some printing with it yesterday.

My eye prefers the warm toned print over the cold toned but when I see a well made print that can take advantage of the more "inky" black of the cold toned paper over the "dark coffee" black of the warm toned paper and a true gray rather then a sort of ivory I wish I could figure out how to take advantage of it in my printing. I tried yesterday extending the print development period to see if that worked any better. I use a factor system for print development. By factor I mean that after exposing the paper and immersion in to the developer I have a timer going and I watch the print for the first faint signs of development and mark that time. Then I develop the print by that time period times 4. So if the first development shows after one minute I develop the print for 4 more minutes for a total development time of 5 minutes. After putting the print through the stop bath, and fix I then look at it in bright light and if it's too dark I scale back the print exposure time by about 10%, if too light I increase exposure time by 10% but I keep the development time constant. With the cold tone papers I tried developing by a factor of 6 so my printing time was extended sometimes to 7-8 minutes. The factor system works well when using different paper/developer combinations to calculate proper development and also can take in to account developer strength as well as temperature and how those conditions can impact proper print development. Since my darkroom can be cold in winter time my chemicals can be as cool as 60 degrees farenheit when I start working and not warm up until the darkroom warms up. If I keep track of the amount of time for first development which can take depending on the temperature from 30 seconds to a minute and a half or more and then factor that time by 4,5,6 or whatever amount of time gives me a print that I consider "correct". I tend to mix a developer solution and discard it after a printing session of around 24 prints so the developer strength is fairly constant.