how to tell when oil paint is dry; what conditions?
I get the idea that you can knife oil paint only so much, then you're basically scraping canvas...and I know that if I still see the marks left by the brush hairs, there's enough thickness of paint to spread...but there are times when there ARE no brush artifacts..sometimes there's enough to knife, sometimes not.
I can add more pigment and resuming knifing, but I might not want to spoil what's there...it would be nice if I had a better grasp of how much time I have, or a clue as to how to set myself up with more pigment to play with.
I hope this question makes sense...thanks for any help.
Seems like you're basically asking a question about blending. Yes, using the knife at a high pressure setting will eventually be counter-productive so try using low pressure settings for that. The brush can also be used for blending if you set the loading option to zero. The ArtRage settings offer a nearly infinate amount of variability and the only way to get a feel for what you want to accomplish is to practice and experiment. Don't forget that you can ctrl-z to undo and always do a Save to keep your various stages of development accessable for later development.