Have printed using the same negatives in the past without either vinegar paper or citric acid. Results were alright, but with more loss of mid tone. I am pretty well convinced that vinegar paper improves my images...and, I think, may reduce exposure time. It is really the combination of the treated paper and the acid bath I am wondering about. Is there any advantage to one over the other...and does using both result in more mid tone...and does it cause chemical being washed off?