A Safe Humidity Band for Stored Paper: Curl, Jam Risk and the Cost of Running a Copier Outside It

This paper addresses a practical question in moisture: paper is mostly water-responsive fibre, and a stack of it is in constant negotiation with the air of the room. Using a self-contained computation from stated assumptions, the study evaluates the options across the range a small operation ordinarily meets and identifies the point at which the balance of cost, quality and material use changes. The headline findings are that jams at 30rh is 4.7; jams at 70rh is 4.7; monthly cost at 30rh usd is 84.6; monthly cost in band usd is 36; extra monthly cost at 70rh usd is 48.6. These figures come from a simulation study: the work is SIMULATED, NOT MEASURED, no physical trials were performed, and every number reported is taken from the deposited computation output so that any reader can reproduce or refute it with local values. The practical value of the result is a rule that can be applied at the point of work without further calculation, together with the tabulated cases from which the rule was derived and a statement of the assumptions on which it depends. Where the computation shows that a widely used practice wastes money or material, that finding is stated directly; where it shows that a popular economy is genuine, the size of the genuine saving is stated with equal directness, so that effort can be directed to the economies that are worth having.