How long to keep a technical file, and how to decide in general terms

Retention is a decision, not a habit. For a children's raincoat, a seller who deletes the file the moment the coat stops selling may lose the very record needed when a parent later reports a seam leaking after heavy rain, or when an authority asks how the coat was assessed. A file kept for a sensible period after last sale protects both the seller and the buyer, because it lets a later question be answered from evidence, not from memory.

How long is sensible depends on the product, not on a universal rule stated here. A raincoat worn by growing children, passed to siblings, and used for several seasons may generate questions long after its last sale, while a short lived product may generate fewer late questions. The seller should reason about product life, sharing, and complaint timing, and should write that reasoning down, rather than picking a period at random.

Product life is the first consideration. A raincoat's seams, waterproofing, and fastenings age with use, washing, and storage, and a seam that leaks after heavy rain may only show itself after a coat has been worn for a while. A file deleted early cannot explain whether that seam was assessed, tested, or changed during production, and the seller will be left without evidence when it matters most.

Sharing is a second consideration. Children's coats are often handed down, sold second hand, or given to younger siblings, so a coat may still be in use long after it stops being sold new. A file that is kept can still answer questions about that coat, while a file that is deleted cannot, even though the coat itself is still keeping a child dry in the rain.

Illustration: a seller keeps 40 raincoat files and imagines that 20 of them, in round illustration terms, are for coats no longer sold, while the rest are for current coats. Those figures, as presented in How long to keep a technical file, and how to decide in general terms, are invented, not measured. They show why retention needs a system: without a retention note, old files accumulate without a plan, and a seller cannot tell which files are still needed, which can be archived, and which can be safely disposed of when their useful life ends.

A retention note for each file should state the reasoning, the period in general terms, and the person responsible for reviewing it. That note turns retention from a vague intention into a decision that can be reviewed and, if needed, extended when new information arrives.

Archiving is different from deleting. A file that is no longer needed day to day can be moved to an archive, where it remains findable but does not clutter the current file system. Archiving should preserve the file's index, its versions, and its dates, so an archived raincoat file can still be read and understood years later, without the original team in the room.

• Reason about product life, sharing, and late complaints before setting a period.
• Write a retention note for each file, with reasoning and a review owner.
• Archive files no longer needed daily, preserving index and versions.
• Review retention decisions when new complaints or information arrive.

Retention often fails in two directions. One is to delete too early, losing evidence for a product still in use. The other is to keep everything forever, without an index or a plan, so that a needed file cannot be found among a mountain of obsolete papers. Both failures stem from the absence of a retention decision, written down and reviewed.

Another failure is to keep files in a form that cannot be read later, such as an old digital format, a faded paper copy, or a password protected file whose password is lost. Retention should include format and access checks, so a file kept for a long period remains usable throughout that period.

Close by writing a retention note for the raincoat file, stating the reasoning in general terms, the archive location, and the review owner. That note should be filed with the file itself, so a future team member can see why the file is kept and when its retention should be reviewed.

Revisit retention when a complaint arrives after sale, when a product is discontinued, or when storage or format changes. Each revisit should ask whether the file is still needed, still findable, and still readable, and should extend retention where the answer to any of those questions requires it.