|Frank H. Mason|
Not terriby lot can be done about it, because according to the practice of the past, it is already mounted on board, I can only refit with the fresh pH balanced matting and museum-quality backing board. Clear acrilic instead of dark green-tinge glass will help.
Definitely, the good way of preserving the image itself will be to reproduce it digitally.
I can imagine the Natural-toned Albrech Durer paper by Hahnemulle will be ideal and resembling the original surface.
melancholic and well drawn.