Amongst my stamp albums, I have one which was improperly stored over the years. Many pages and stamps present iron-based foxing (definitely not micro-organic). [As a side note, in this album foxing has affected a far higher percentage of 19th Century US stamps than 19th Century GB stamps - it has to do with the paper manufacturing process, especially on bleached paper.]
Researching and experimenting with various methods, I am sure by now that there is no 'one size fits all' approach. And most chemical approaches tend to damage the paper and the ink
How are you dealing with foxing, please? And how much value is losing a stamp with iron foxing from your point of view?
Below is a link to a nice article on this topic:https://inspectapedia.com/mold/Foxing_Stains.php