I have been doing my own Black and White Processing and Printing for over forty years now and have never had an issue with a print after washing.
Started using Ilford fiber paper for five years now and used the same washing methods as before. I stick them in a bath tub and use a fish tank water pump to circulate the water around them and turn a couple of times. Washing for a good hour or so.
Well I have decided to mat and frame a couple after deciding on the ones I will do, I suddenly noticed some orange marks on the back of a few prints, the print sides are fine. So I thought wash them again for a while. Well after being in there for twenty minutes I went in and turned them over and got a serious shock.......there are grey blotches about an inch or so wide in various places. The orange areas have darkened to a brown !!!!
What is going on here, the grey blotches are on two prints and one is a recent print done a month ago, that one only has to areas but a print from four years ago has six areas of botching.
Help and advice needed please.