I may be coming into an Aletta 4x5, very lightly used, in exchange for some work on a couple other cameras. The current owner has recently tested the bellows (at the suggestion of a third party) and discovered that 7 minutes in full sun with a blank lens board in place will significantly fog Efke 25.
I know the "best" solution is to build a new bellows to replace the translucent one, and that's my long term plan, but I can easily see it taking a year or two to get to that kind of project (tapered bellows, which is more complex to make than a straight one), and I won't want to wait that long if I get this camera. Meantime, suggestions for adding opacity to the existing bellows without greatly reducing compression, flexibility, or durability would be welcome. I've been thinking of spray paint, perhaps a "bumper flex" type from an auto parts store, or using spray adhesive to apply a layer of black plastic of the type used for inner packaging of film and enlarging paper. And, of course, there's always "shoot indoors and minimize dark slide open time."
What other options exist?