May I suggest that you don't put a puddle of Silver Nitrate solution on the paper and if coating by brush redip the brush in the solution as you coat.
I have just printed two test strips to see if the stains would be formed. On purposely, I poured and started coating from the middle. I must say, although they are quite weak (probably due to acidity), they are visible. and that is not good
If you pour SN to the edge of your coating area and later mask that part, it might also work.
But the simplest way seems to be dipping the brush into SN as clive suggested. I would do some tests tomorrow.
I have increased the concentration and decreased the amount of of citric acid in order to lessen the dilution of final volume of SN+CA used for coating.
I have mixed %50 citric acid. (you can dissolve up to 70grams of CA per 100ml)
I added 1 drop of %50 CA per 0,5ml of SN.
So roughly to coat 8x10 inches area it is 1,5ml SN + 3drops of %50 CA. (The optimum amount of SN might change with paper so consider it as a guide only)
I left the coated paper in 27C %60RH condition for an hour. There was no fogging. If fogging happens it happens before the paper gets dry, so I believe the amount of CA is safe.
Maintaining the solution used for coating around the optimum volume would help IMO.The coating would be easier and less prone to problems because it would require less brush strokes or less passes with glass rod.
My pleasure, coating wavy paper with rod is problematic. I used to do coat with glass rod. I taped the paper from all corners, sometimes the whole edge to get it as flat as possible. I am now trying DaVinci brushes, but I will try the rod again to compare.
Anyway, If anyone has a tip to flatten the wavy paper after gelatin coating, that would be great.