I keep my saddle pretty clean and in the house, so it's not in extreme temperatures. I use Supple saddle soap and every once in a while some Effax. I only use my saddle once a week, and lately I've noticed that there are white patches here and there, mostly on the flaps. I can rub it off but I don't know what it is. It's not sticky or oily. The Supple is pretty old, does it go "bad"?
Anyone have any ideas? I don't see how it would be mold when the house is dry and the saddle isn't getting wet. Have I used too much Effax so that it's percolating out of the leather?
I realize that I'm generalizing here, but as is often the case when I generalize, I don't care. ~ Dave Barry
Clean the areas with white vinegar since it will kill the mold spores. Mold will appear in even warm and dry places. The spores are there somewhere.
The other possibility is grease coming up out of the leather. If someone has used excesive amounts of conditioner and left too much on the leather it will make a white film of fatty grease.
Effax is wonderful stuff. I use it myself. Excessive amounts of it are not good though.
When you use it, buff off the excess with a piece of old toweling. I love the finish after you buff it good.
Try the things I suggested and see if it helps.