There is honestly nothing quite like shooting medium format film on a trip. You pack your bags, carefully load up your camera backpack with a few rolls of Portra or Ilford, and dream about those massive, beautifully detailed negatives you are going to bring home. But if your destination happens to be a tropical coastline, a humid rainforest, or anywhere with swampy summer weather, you might be walking into a trap without even knowing it.

A while back, a friend of mine took his beloved twin-lens reflex to Southeast Asia for a month. He shot dozens of rolls of 120 film, sweating through his shirts, fully embracing the analog travel life. But when he finally got his scans back from the lab, his heart sank. The images were covered in strange, clustered black spots. On a few frames, he could actually read the frame numbers from the backing paper perfectly stamped into the sky of his landscapes. The culprit? Humidity.

High moisture environments can absolutely wreck medium format film, leading to a nightmare phenomenon known as paper flaking or emulsion mottling. If you are planning to shoot 120 film anywhere hot and sticky, here is exactly what is happening inside your camera and how you can stop it from ruining your hard-earned photos.

The Vulnerable Anatomy of 120 Film

To understand why this happens, we have to look at how 120 film is actually built. Unlike 35mm film, which is safely coiled up inside a light-tight metal or plastic cassette with a neat little felt velvet trapdoor, 120 film is basically naked. It is just a strip of raw photographic film rolled onto a plastic spool, backed by a long strip of printed paper. This paper backing is the only thing protecting your unexposed film from the sun.

That backing paper is relatively thick and opaque, but at the end of the day, it is still paper. It is porous and incredibly absorbent. In normal room-temperature environments, this design works beautifully and has been working since the early 1900s. But when you introduce extreme humidity, that protective paper backfires and turns into a sponge.

What Exactly is Paper Flaking and Mottling?

When you are walking around a humid environment, the backing paper on your 120 film starts absorbing water from the air. As paper absorbs moisture, it swells slightly. At the same time, the gelatin emulsion on the actual film strip—the gooey, light-sensitive layer that records your image—also absorbs moisture. Gelatin gets extremely soft and incredibly sticky when it is warm and humid.

Now, picture what is happening inside your camera. You have a swollen, damp piece of backing paper tightly wrapped and pressed directly against a sticky, warm layer of film emulsion. Since the film is rolled so tightly on the spool, the two layers basically fuse together. It is like leaving a piece of paper on a wet painted table; when you try to pull it up later, half the paper stays stuck to the table.

When the lab goes to unroll your film in the darkroom, they literally have to rip the paper off the emulsion. Tiny microscopic flakes of the paper, or the black ink used to print the brand name and frame numbers, rip off and stay glued to your film. When the film is processed, those flakes block the developer chemicals, leaving dense black specks, weird textured patterns, or literal ghost numbers burned into your negative.

How to Protect Your Rolls in the Tropics

Do not let this scare you away from taking your medium format camera on your next tropical vacation. You absolutely can shoot 120 film in high humidity, but you have to be much more intentional about how you store and handle your rolls. Here is how I keep my film safe when I am traveling somewhere humid.

• Use the Ziploc and Silica Gel strategy: This is my golden rule for travel. I keep all my unexposed 120 film inside a heavy-duty Ziploc bag, and I toss in a handful of reusable silica gel packets. Silica gel aggressively absorbs moisture from the air inside the bag, creating a micro-climate of dry air around your film. When you finish shooting a roll, put it right back in the dry bag.
• Do not leave film sitting in the camera: In dry climates, you can leave a half-shot roll in your camera for three months and it will be totally fine. In the tropics, a roll left in the camera for a week is a ticking time bomb. The inside of your camera is dark and warm—the perfect environment for moisture to turn your film to sticky glue or even grow fungus. If you load a roll of 120 on a humid trip, commit to finishing it that same day or the next morning.
• Acclimate your gear slowly: One of the fastest ways to introduce moisture into your film is through condensation. If you keep your camera and film in a heavily air-conditioned hotel room overnight, and then immediately step out into 90-degree jungle heat, your gear will instantly fog up and sweat. That condensation gets right into the paper backing. To avoid this, put your camera and film in a sealed plastic bag before you leave the cold room, and let it slowly warm up to the outside temperature for about twenty minutes before taking it out of the bag.
• Keep the original wrappers on: A lot of modern 120 film comes tightly sealed in foil wrappers. Those wrappers are factory-sealed in a humidity-controlled environment. Do not open the foil wrapper until the physical moment you are standing there ready to load the camera.

Dealing With the Aftermath

If you suspect your film might have been subjected to extreme humidity and you are worried the paper has fused, do not try to develop it at home unless you are very experienced. Let your local lab know what happened when you drop it off. Lab technicians have seen it all, and if they know the film might be sticky, they can unroll it with extra care to minimize the tearing.

They might not be able to save every frame, and you still might get some of that classic mottling texture, but giving them a heads-up prevents them from accidentally yanking the paper and causing massive tears across your entire roll.

Getting the Right Gear for the Elements

Shooting medium format is incredibly rewarding, and figuring out the quirks of 120 film is just part of the analog journey. If you do not have a camera that uses 120 film yet but you are craving those massive, high-resolution negatives, picking up a reliable system is the first step. You can check out our available medium format cameras to find a rig that fits your shooting style.

Of course, keeping your gear safe from the elements whether it is rain, humidity, or dust is non-negotiable on a trip. A good weather-resistant setup provides a first line of defense before moisture even reaches your film. Take a look at our current selection of camera bags to make sure you have a solid home base for your gear while you are on the move with your silica packets.

At the end of the day, film is an organic, physical medium. It responds to the environment just like we do. As long as you respect the climate you are shooting in, keep things sealed up dry, and shoot through your rolls efficiently, you will come home with incredible medium format shots—completely free of backing paper ghost numbers.