What's happening to my pictures?
 

I have several prints that have been framed in my finished basement and I'm getting some sort of soiling on them. It almost looks like a buildup of dust and when you brush it off, it leaves a small soil stain. It's only happening to these prints and nothing else. It's not a damp basement and stays anywhere from 62 degrees in the winter to about 67 degrees in the summer. I have a lot of other framed photos and whatnot but they're all fine. Not sure if it's just the paper type on these prints or what. Does anyone have any thoughts?

Thanks

I suspect mold or mildew caused by humidity

yup- looks like it to me too

I third that....

Definitely

Keep in mind that although it may not feel damp to you, there may still be enough moisture to promote mold / mildew growth. If it continues to be an issue or if you plan to store paper collectibles down there, it sounds like a dehumidifier may be needed.

Probably a combination of the paper type (since no other pictures are like this) and environment. Place a humidity gauge down stairs and see what the humidity is, if it is above 60% you may need some form of dehumidifier

Yeah, you'd be surprised how damp a basement can get without knowing it. In our last house, we never had any flooding but I think there was a high water table and we had the dehumidifier running 24/7, every day of the year. Even during the driest winter months it would suck a couple gallons of water out of the air every day. During the summer it would fill up a 35 gallon bucket every few days. This is interior Connecticut, not some Louisiana bayou town or something. Basement was unfinished, but still, that's a lot of water just sitting in the air.

Thanks all. Humidity is 62% from a gauge placed there yesterday. Is there a simple way to clean the prints to get the soil marks off of them?

Depending on your collectible type Humidity should be less than 60%. Wood antiques should be about 50-55%. If it is mostly paper stuff you are worried about try to get it less than 50% (40-45%) but the lower you go the more uncomfortable it is to be in that environment for you. I think if you can get it no higher than 50% you should be okay for most collectible types. If most of your stuff is in one smaller room and not the whole basement a small room dehumidifier would work

I mention this only because it worked for me on an inexpensive item that was white like these are...so please use extreme caution if these are of great value.

A LIGHT rubdown with a Magic Eraser. The kitchen/bathroom sponge thingy. I wouldn't wet it before use obviously. Just a gentle couple swipes and you should be able to tell if it's going to help at all.