Airbed in question
http://airbeds4less.com/product/queen-size-air-mattress.html
Used soapy water on the flat grey vinyl but that white felt top just absorbs the soapy water. Visual searching has not been successful, and the felt doesn’t help that either.
Cut out a smallish square from a plastic bag, it will lift up where the leak is.
Sounds frustrating! I lived off a similar airbed for awhile, and was always annoyed at it deflating slowly over the night. Searched for a tear in rain, it ended up being the valve itself was passing. Bit of ingenuity had that patched up quickly.
So since you didn’t mention the valve, and I’d think it to be one of the most likely leak locations, maybe close investigation there before looking over every sq inch of mattress?
Valves were first thing I checked. It’s been a great bed for almost exactly one year. Rarely lost air. I think I’ll try the plastic bag trick with some plastic wrap
My experience with air beds has been that while they last, they’re wonderful, and that once they start losing air, it’s simply a waste of time and trouble to isolate it.
I’ve decided that they’re just not designed for long term sleeping, and when my last air mattress started leaving me deposited on the floor every morning, I just bought a cheap regular mattress. It having lasted you for a year is just about my expectations after having gone through three in three years.
I have had a lot of experience using these things for car camping. Decades. Once they begin to leak, it is a lot of work to find and repair holes. It always involves a lot of soapy water outside on the lawn in warm weather. If the holes are really tiny, and you will have those, they will be impossible to find.
I’ve had great luck finding leaks in vinyl “camping size” airbeds. I got to thinking, even if I found the leak in the felt area, patching it could be an issue.
By analogy with finding punctures in a bicycle tube - find a swimming pool or other suitably large body of water you can inflate it in, and look for the bubbles?
Shouldn’t be that hard. Inflate it very firmly and get someone to lie on it while you slowly pass your wet hands just above the surface. If you have very insensitive hands use your moistened inner wrists. You should readily find even a tiny leak.
Don’t know if this would work for this application, but:
Leaks in swimming pool plumbing are sometimes located using shaving cream - which is soap and water in a foam.
Be careful of how much time you spend trying to locate a hole you probably won’t be able to patch.
Just for giggles, see if you can find a way to patch it before spending more time looking for it.
iPhone or Android microphone might pick up a hiss if you have someone lay on the bed, then scan the surface.
There’s a nice oscilloscope app for Apple, likely Android as well.
I use air beds when I’m living in east Asia and they just plain don’t last much longer than three months.
Trying putting a foam earplug in one ear, and a drinking straw in the other. Then get on the bed and methodically move the straw around listening for the leak. I’ve had good luck doing this with bicycle tires.
While trying this method, substituting a funnel for a straw, I ended up FEELING the leak on my face. The hole wasn’t even in the felt area. It’s back to holding air as good as it was.