Personally, I have never encountered that problem, but as I am preparing an article about the stability of (not only) RC papers for an online magazine, I have seen some examples of damaged prints. (I am indebted to three gentlemen of Agfa who took the time to present the examples to me, and to explain the cures.) So I can give you a few qualitative hints and keep my promise (given in an earlier posting) to disseminate some of the info I collected.(posted 8587 days ago)1) You are right in that working to exacting archival standards will not protect you from silver oxidation. Silver, albeit being regarded as a "noble" metal, silver is actually quite reactive, and it doesn't take much to oxidise the silver image.
2) Damage to prints can become visible in as little as a month.(I saw examples of prints ruined in four weeks by hanging them in a barber's shop, i.e. in an atmosphere with a lot of formaldehyde and other solvents - boy, I'am glad I haven't got to work there!)
3) Warm-tone papers having a silver image consisting of finer grains, thus having more effective surface for the oxidants to attack, seem more vulnerable, but the difference is small.
4) The process is accelerated by light, which means that storing your prints in the dark will make them a bit more stable, but eventually, if the air is bad, this will not fully cure the problem.
5) Partial toning in selenium (such as the toning for a better D_max in highly diluted selenium toner) will not protect the image sufficiently. If you tone to get archivally stable images, tone until there is a clear change in image tone, i.e. in strong selenium and/or for longer toning times.
6) For partial toning in gold toner the same holds.
7) Sulfiding toners (such as the bleach-and-redevelopment toners with ferri/KBr bleach and sodium sulfide toner or the polysulfide variant, like Agfa Viradon) do protect the image. It is then as stable as it can get (but brown).
8) There is a product by Agfa, Sistan, which protects the image by precipitating any soluble (= oxidized) silver ion in the emulsion in the form of an insoluble salt. Sistan is basically a potassium thiocyanate solution plus a wetting agent, which is used as the final bath (thus no washing after the sistan treatment). It is said to be compatible with other toning methods (such as partial selenium toning), and also with spotting. There is a more or less equivalent product by Fuji, which is called AG Guard, which, however, appears to be offered on the Japanese market only.
9) No manufacturer of photo paper will give you any guarantee that images made on his paper will last for whatever period, even given proper processing. This is not because the manufacturers are bad guys, it's because they can't take any responsibility for the air quality at the place where the image is hung.
10) RC paper does NOT appear to be inherently worse than FB paper. The problems reported by Ctein in the nineties are said to have been solved by the addition of anti-oxidants to the base during major revisions of the papers in the late nineties. (I am quoting this from one manufacturer.)
Thomas Wollstein