I have several rolls of exposed 35mm that have been stored in a refrigerator for 10 yrs. What is the best method to develop them? Do I need to keep them cold in transport or allow them to warm to room temp., and do I keep them in or out of canisters to avoid issues with condensation before processing??
Are you going to develop the films yourself or are you going to take them to a lab? If they're exposed films, you don't need to worry about condensation if they're not going to be in warm temperatures for too long before development. Remember that the first stage of the actual film processing is submersing the film in developer, so they're going to get fully submersed anyway.
If you're going to process them yourself, then condensation may pose a problem is when you're loading the film onto the developing reel. I've found if the developing reel is still wet from a previous development, then it can be a bit more tricky to load. I think to minimise risk, you should either process them absolutely as soon as possible after removing from the fridge, so that they are in the developing tank before condensation can form, or, keep them at the same temperature, perhaps with an ice pack in a cool bag until you can take them to be processed. If processing them yourself, get everything ready including the chemicals, film canister opener and reel etc, so that in the minimum amount of time you can get the film from the fridge and into the developer solution.
If you're going to a lab, talk to the lab first; I'm sure they'll have experience with rescuing films and will advise on what to do in order to take the films to them.
Most importantly, don't go in for getting them all processed at the same time. Pick one film out, and deal with that as a test, whether going to a lab or doing it yourself. See the results from that film and see whether anything needs to be done differently, then at least you're only losing one instead of all of them.
I'm sure that a specialist lab will be experienced in dealing with films that have been dropped in rivers, the sea and washing machines etc, so they would probably be able to give the best advice.
Note here that I've not given any advice on whether to use specific chemicals, changing the dilution etc may or may not help expired films to develop better. It may be worth looking for separate answers on here about developing expired films, which would answer that part of the question, eg: What's the best way to develop old, exposed film?
Each film is packaged in an airtight wrapper. If the film has just been removed from cold storage, allow about 8 hours before opening. Once the film has warmed and opened, no additional special treatment is necessary. However film is made in batches. Each batch is slightly different. Color film manufactured years ago can display significant color differences compared to fresh film. Photofinishers receive data to be installed in their printers or use fresh test films to set the color balance data in printing devices. Outdated films may print with a substandard color bias. Photo labs can handle but will they make the extra effort? Outdated slide film is likely to develop up with a color bias.