There are few feelings worse in film photography than getting your freshly developed scans back from the lab, eagerly opening the folder on your computer, and seeing massive, blown-out orange streaks across your favorite shots. It is devastating. Sometimes a light leak can look artistic, but most of the time, it just ruins that perfectly composed portrait or landscape you worked so hard to capture.

The culprit? It is almost always the light seals. If you collect or shoot vintage film cameras, especially SLRs and rangefinders from the 1970s and 1980s, you are going to encounter bad light seals. It is basically a rite of passage. Over the decades, the original polyurethane foam used to block light from entering the film door degrades. It turns away from a nice, spongy cushion into a sticky, tar-like black goo that gets everywhere, stains your fingers, and absolutely entirely fails to keep light out of your camera.

When I first started shooting film, I thought a camera with bad seals was a dead camera. I assumed replacing them required a degree in mechanical engineering or an expensive trip to a camera repair wizard. But honestly? Replacing light seals is one of the easiest, cheapest, and most satisfying DIY projects a film photographer can do. It takes a little patience and a steady hand, but you can absolutely do it at your kitchen table. Here is my personal, tried-and-true method for getting your camera light-tight again.

What You Will Need

Before you dig into the gooey mess inside your camera back, you need to gather a few essential supplies. You probably already have half of these under your bathroom sink.

• Light seal foam: You can buy a sheet of 1.5mm or 2mm adhesive-backed camera foam online and cut it yourself, or you can buy a pre-cut kit specifically outlaid for your camera model. If it is your first time, I highly recommend spending the extra few dollars on a pre-cut laser kit. It saves you from having to slice impossibly thin strips with a ruler.
• Rubbing alcohol (Isopropyl 90% or higher): This is to break down the old, sticky foam residue. Lighter fluid (naphtha) also works incredibly well for cutting through the adhesive.
• Bamboo skewers or toothpicks: Do not use metal screwdrivers to scrape out the old foam. Metal scrapes the black paint off the camera body, which can cause internal reflections. Bamboo skewers are firm enough to scrape but soft enough not to damage your camera.
• Q-tips and cotton swabs: You will need plenty of these to wipe the channels clean.
• A piece of stiff paper or cardstock: This is my secret weapon for protecting the delicate shutter curtain.
• Tweezers: For placing the new, tiny strips of foam into the tight door channels.

Step 1: The Cleanup (The Messiest Part)

I am not going to sugarcoat it: removing the old light seal goo is tedious. It is easily eighty percent of the work. But a clean surface is absolutely critical for the new adhesive to stick properly.

Before you start scraping, cut a small piece of cardstock or stiff paper and gently place it over the shutter curtain opening inside the camera. The shutter curtain is incredibly fragile—especially if it is a cloth curtain. If a blob of sticky black tar falls onto the curtain, or worse, if you slip with your skewer and poke the cloth, the camera is ruined. Protect the shutter at all costs.

Dip a Q-tip into your alcohol or lighter fluid and run it along the grooves where the old seals are sitting. Give the solvent a minute to soak in and loosen the old adhesive. Then, take your bamboo skewer and start gently scraping the channels from one end to the other. You will start pulling up globs of black gunk. Wipe the skewer on a paper towel and repeat. Go back and forth with wet Q-tips and your skewer until those channels are completely completely bare metal. Do the same for the hinge seal (the rectangular pad where the door swings open) and the mirror cushion, which is located inside the lens mount where the mirror slaps up.

Step 2: Prepping the New Seals

If you bought a pre-cut kit, carefully peel the thin strips off the backing paper using your tweezers. If you are cutting your own from a sheet, use a sharp hobby knife and a metal ruler to cut strips that are roughly 1.5mm wide. You want them to sit snug inside the channel without bulging out. If the foam is too thick, you will not be able to close the camera door.

Here is my absolute favorite trick for laying down foam strips: once you peel the backing paper off, take a tiny bit of water or alcohol on a Q-tip and lightly moisten the sticky side of the foam. Alternatively, some people just quickly dab it with hand sanitizer. Why? Camera foam adhesive is notoriously aggressive. As soon as it touches the camera, it bonds instantly. By wetting it lightly, you temporarily neutralize the glue. This gives you about sixty seconds to slide the foam strip perfectly into place before the water evaporates and the glue sets permanently. It is a total lifesaver for the tight door channels.

Step 3: Installing the Door Channels and Hinge

Start with the channels that run along the top and bottom of the camera back. Using your tweezers, grab an extreme end of the moistened foam strip. Gently lower it into one end of the channel. Then, using the flat edge of your bamboo skewer or toothpick, slowly press the foam down into the groove, working your way across the camera entirely. Do not stretch the foam as you lay it down; just let it lay naturally. Stretching it will cause it to shrink back later, leaving gaps where light can sneak in.

Next, replace the hinge seal. This one is usually a much wider piece of foam that sits near the door latch or the hinge spindle. Plop it down, press it firm, and you are done with the back.

Step 4: The Mirror Bumper

The mirror bumper is the little strip of foam inside the mirror box that absorbs the shock when you take a picture. Without it, your camera might sound incredibly loud and harsh, and the mirror slapping hard against bare metal can eventually cause mechanical issues or throw off your focus.

Working inside the mirror box is delicate. Above the mirror is the focusing screen, which is usually made of scored plastic. If you get alcohol or lighter fluid on the focusing screen, it can melt or permanently fog the plastic. Use minimal solvent here when cleaning old goo, and hold the camera upside down so gravity pulls any loose gunk onto the table, not into the depths of your camera body. Once clean, use your tweezers to carefully place the new foam bumper across the metal lip.

Step 5: The Test

Once all your new foam is in place, leave the camera open for an hour or so to let any leftover alcohol evaporate securely. Then, try closing the camera back. It should feel a bit snugger than it used to, and it might require a firm click to latch perfectly. This is a good thing! It means the foam is doing its job pressing against the rim.

Take your newly sealed camera into a dark closet, pull the lens off, and shine a bright LED flashlight around the seams of the film door. Look through the lens mount. If you don't see any light bleeding through the edges of the door, congratulations—you have successfully sealed your camera. You can finally go shoot that roll of Portra 400 without the fear of orange streaks ruining everything.

Replacing light seals is a fantastic way to bond with a new vintage pickup and restore a piece of mechanical history. But hey, I understand that scraping fifty-year-old tar out of thin metal gaps is not everyone's idea of a fun weekend. If you would rather skip right to the part where you take beautiful photos, I have you covered. When you buy from my shop, I have already done all the messy, tedious maintenance work for you. Every camera gets completely evaluated and freshly sealed before it ever hits the mail. If you want something guaranteed to shoot perfectly right out of the box, check out my current selection of freshly restored SLR cameras. Pick one up, load some film, and just focus on making great images.