Is It Fox Rot Or Mildew That I Can See On My Grandfather's FDC's?

I recently was given some first day covers (FDC) that my grandfather used to collect. Despite being a stamp, rather than an FDC, collector I wanted to keep these for sentimental reasons. However, all but 4 covers have marks on them and I'm not sure whether they are fox rot (which I read does not contaminate other stamps) or mildew (which can contaminate other stamps).

Could anyone please advice whether this is fox rot or mildew? If it is mildew would cutting away the areas stained permit keeping the FDC's without risking my own collection?

I have attached some photos which I hope might help.

Tremendous thanks to anyone who might be able to assist!

Opinion:
Classic foxing. Can be restored with care.
Resulted from storage in a warm humid climate.

Google stamp preservation.

do tell please? I too, would like to know how one would proceed with this situation. Thanks in advance Rod

Caution use at your own risk.
Experience: I have only used mild bleach occasionally, on a foxing spot
on a stamp edge (near the perfs) and immediately soaked in clear cold water.

Extensive foxing, I pass on.

Preservation and Care of Philatelic Materials
Subsidiary Page 6
Proper Handling of Stamps and Covers


We frequently come by cards and covers which have tear damage repaired with plastic tape. Serious trouble is certainly at hand with such items. You may think, and probably correctly so, that further deterioration of the item can be avoided by removal of the plastic tape. The utility of Scotch tape and other plastic tapes is legend; however, such tapes should absolutely never under any circumstances be used to repair philatelic materials, even temporarily. The best advice in dealing with the repair
of items mended with plastic tape is to seek the aid and services of a professional conservationist.

Cardboard is another item to be kept well away from our philatelic materials. It is generally highly acidic, and the chemicals in cardboard are rapidly transferred and hasten destruction. If you require a rigid support of a philatelic item, use an all-rag type of board.

Conservators use chemical baths to eliminate mildew growth and stains. Frequently, when papers have been cleaned and bleached, they are dipped in a gelatin bath in order to restore the paper. The glutinous sizing of the paper adds strength to it, and sometimes a corrective dye will be added to the gelatin bath in order to give the paper a tint close to its original color.

Foxing, which is a stain caused by fungal growth, can often be removed by using a potassium permanganate solution of five drops per pint of water. Carbon tetrachloride or benzine are effective in removing grease and oily stains. These chemicals are very hazardous and must be used according to instructions on the containers. Th e best advice is to let the professional clean your philatelic items.

Restoration of older stamps which have become oxidized can be effected with hydrogen peroxide solution, five drops per pint of water.
Advanced restorative techniques which should only be used by the experienced professional restorer include inlaying and cellulose acetate strengthing.

We cannot stress enough that the chemical restoration methods mentioned in this section are best applied by professional restorers who are experienced with the chemicals and their effects. The various methods are mentioned here only to provide you with some possibilities best explored with the professionals.

Conservators tell us that the leather covers, corners, and backs of our albums will benefit from treatment with potassium lactate solution every two years to preserve the leather. On the other hand, cloth bound albums require little attention beyond the occasional dusting. The best practice is to mount your philatelic materials on acid-free album pages.

Hi Rod222,

Thank you for your extremely detailed and helpful reply and advice.

From what I know the covers were stored in an open plastic bag in a cardboard box. Not sure about it being a "warm" climate as my parents who had these live in the UK, but it can definitely get wet there.

Thank you again for taking the time to reply to my message. Deeply appreciated!

Cold and damp are the bad combination here!

You're welcome,
enjoy the forum
I have a $4 ebay temp / humidity meter, at my desk here.
Humidity can vary 48% -78% over 48 hrs
In a plastic bag, does not help, can retain some moisture.

Just an aside, FDC (First Day Covers) have to be in pristine condition, to hold any value, damaged ones are nearly impossible to move.

I collect them, as I don't collect for future resale.