MUSEUM TESTED METHOD OF KILLING MILDEW ON LEATHER
RAIN, RAIN GO AWAY.... MILDEW REMOVAL FROM SADDLERY  Mold and mildew are fungi, relatives of the mushrooms we eat. Mushrooms grow rampantly when the weather is damp. As the tiny "fruiting bodies" at their tips mature, they bloom and burst to spew billions spores into the air. If you rub a patch of mold or mildew you will send spores throughout everything in your tack room! Take moldy leather out of the tack room and clean it outdoors. That way, you'll avoid filling the air in the tack room with mold spores that will simply inoculate other items in your enclosed tack room. Using a chlorine based product to kill mildew on leather will do the same thing to the leather that it does to your hands and skin when you expose your skin to chlorines- DRYING & CRACKING. After all, leather IS skin! First start wiping away any surface mold with a damp rag. Wipe and capture as much of the mold as you can then throw the rag away. Don't rinse and reuse your rags! That only spreads the mold spores. Use an old toothbrush to clean stitching lines and crevices. Throw toothbrush away. Finish cleaning the leather using a water-based, pH neutral product ( Murphy's Oil Soap, others) to float away any remaining organic surface dirt that could support mold and mildew growth. Dry the tack in the sun to allow the water to evaporate and to take advantage of the disinfectant properties of the sun's ultraviolet light. (Do not use glycerine based products. They act as "humectrants" which means glycerine acts to attract air moisture) Products such as "Leather Therapy" work well. The below recipe is used by museums to "kill" mildew on antique leather: Not:e: This recipe treats a LOT of leather. You may wish to make a small batch. 1/2 Cup Distilled Water. 1/2 Cup Rubbing Alcohol. Aprox. 1 Tablespoon Lysol. Dampen a small piece of terry cloth or other soft rag  and lightly rub the surface of the leather.  Do not soak the leather!!! The Lysol & Alcohol will kill the mold & mildew.  Let the leather air dry naturally. Do not dry in the sun. OIL leather when dried with a good saddle oil.