I sun cure my Orientals and Flue Cure varieties. (Although I prime). I first wilt/begin yellowing (half yellow or more) in the shop before moving to full sun. This will help prevent drying green. I have tried wilting only in the shop and moving to sun while still mostly green, but experienced quite a bit of drying green. I also string my leaves as close together as possible.
Istanbulin's Sun Curing thread: http://fairtradetobacco.com/threads/2242-Sun-Curing
Although the photos show primed leaf at different stages of maturity, and the final color for those stages, the images may help you find a happy medium for stalk curing and what to expect from the different colors: http://fairtradetobacco.com/threads/1799-FAQ-about-Turkish-tobaccos?p=77382&viewfull=1#post77382
Istanbulin's Sun Curing thread: http://fairtradetobacco.com/threads/2242-Sun-Curing
Although the photos show primed leaf at different stages of maturity, and the final color for those stages, the images may help you find a happy medium for stalk curing and what to expect from the different colors: http://fairtradetobacco.com/threads/1799-FAQ-about-Turkish-tobaccos?p=77382&viewfull=1#post77382