vstirling's Profile

I work in framing / frame design consultation. A few tips I always give to customers when framing things for a bathroom:

You can have a frame shop heat mount a print to the backing material (acid free foam core). If moisture gets into the frame, the entire piece will be glued down so there's no danger of warping. This kind of mounting is reversible, but I wouldn't recommend it for anything valuable or one-of-a-kind.

Use Plexiglass. It doesn't fog up like regular glass, although really long, hot showers (and no vent system) might cause condensation.

Use mats or spacers to keep the Plexiglass off the art, so if moisture gets in, the paper won't stick to the Plexi.

Seal the layers of Plexiglass, matting or spacers, and backing with removable tape on all sides. That creates what's essentially a sealed solid block that won't allow moisture to seep in.

Metal frames hold up better than wood in a humid room and there are plenty of styles available with beading, details, distressed finishes - not just minimalist streamlined stuff.

I have a reproduction vintage print in my bathroom which used all the methods listed above. I take long, hot showers that create a lot of humidity, despite the exhaust vent, and the Plexiglass rarely ever fogs and no moisture has affected it after 2 years.
It's a lot to do for bathroom art, but I'd rather have well-sealed pieces that last instead of throw-away artwork I'd have to replace if it gets ruined. There are DIY framing tutorials online and most frame shops will cut just mats and glass for you; assembling it yourself obviously saves money.