I used to use acetic acid for mixing it but now I am using citric acid. The formulas I have found on the internet often pointed to a %5 solution of citric acid, but I started using %10 because CA is a weak acid.
Originally Posted by Mainecoonmaniac
I am using %12 SN solution too. To coat an area of 8x10 inches I would measure 1,5ml of SN and add 1,5 ml of %5 citric acid and mix it (3ml in total that is a too much to coat IMO).
But I am rather going to do it like this for 8x10 inch, 1,5ml of SN plus mixed with 0,5ml %20 citric acid. The final solution would be less diluted with water and easier to coat IMO. Acidity would be the quite similar, slightly stronger.
It is quite arid here actually, it is around %25-30RH during the day. I use a USM humidifier in the work place and keep the humidity between %50 to %60. That is also one of the reasons I prefer stronger acidity in the mixture to ensure that the papers are not fogged prematurely. I am yet to test if low humidity or somewhat moderate humidity is better for salt print. (in terms of dmax and tonality)