Every office has the same Monday-morning ritual. Someone opens the copier, pulls out a crumpled sheet, slams the drawer, tries again. By ten o’clock a technician has been called. By Thursday the jams have mysteriously stopped — until next Monday.
Often the machine is fine. The problem is the air it’s working in.
Why does humid air make printers jam?
Paper is made of plant fibres that absorb water from the air. In a damp office, each sheet swells slightly, goes limp, and sheets stick to each other. Limp, swollen paper curls, double-feeds and jams; and in a laser printer, the hot fuser dries one side faster than the other, so prints come out curled. Damp paper also takes toner poorly, so text can look faded, smudged or flaky.
Libraries and archives control humidity for exactly this reason: paper reacts to every change in the air around it. (The Library of Congress’s collections-care guidance is a good primer.)
If your printer jams on Monday and works on Thursday, the printer didn’t change. The humidity did.
Why do printers jam more on Mondays?
Most offices turn off air-conditioning at night and over the weekend. With the building sealed, humidity climbs — often back to 70–80% by Monday morning. Paper sitting open in printer trays and on shelves soaks it up. Then the first print job of the week hits a tray full of damp paper. (Why weekends are the danger zone for offices.)
How do you know humidity is causing your print problems?
Jams and double-feeds that get worse on Mondays and in the rainy season, curled or wavy prints, patchy toner and paper that feels soft or cool.
- Jams and double-feeds worse on Mondays and in the rainy season
- Prints coming out curled or wavy
- Faded, patchy or smudged toner on otherwise new cartridges
- Paper that feels soft or slightly cool to the touch
- Envelopes sealing themselves in the box
- Labels lifting off their sheets
Other office equipment that hates damp
- Projectors and screens — dust and moisture inside the optics, foggy lenses, early failures.
- Laptops and desktop PCs — corroded ports and connectors. (Fungus on the lens, rust in the laptop.)
- Paper records and stationery — envelopes, letterheads and forms warp and stick.
- Wooden desks and cabinets — drawers that swell and jam.
How do you stop paper jams in a humid office?
Keep paper sealed until use, load only what you need, store reams flat off the floor — and keep the print room around 45–55% humidity.
- Keep paper sealed in its wrapper until the day you use it.
- Load only what you need — don’t leave a full tray open over a weekend.
- Store reams flat on a shelf, not on the floor or against an outside wall.
- Fan the stack before loading to separate sheets.
- Flip the stack if prints curl one way consistently.
- Use the paper type setting that matches your paper weight.
The fix that solves it
Control the humidity of the room where the printers, paper and records live. Holding the print room or office floor at about 45–55% keeps paper stable and stops the weekend spike. A small print room or records room suits a 20 L/day unit such as DRYAir’s DA-20L; an open-plan floor the DA-35L. Leave it running after hours on its humidistat — that is when the damage happens. DRYAir’s page on the benefits of dehumidifiers covers offices in more detail.
The bottom line
Paper is a humidity sensor that costs you money every time it fails. Keep it sealed, keep it off the floor, and keep the room dry — and the Monday-morning jam ritual becomes a thing of the past.
Questions readers ask
Why does paper jam more in humid weather?
Paper is hygroscopic: it absorbs moisture from the air, swells and becomes limp. Sheets curl, stick together and feed two at a time, and heat from a laser printer’s fuser makes damp paper curl even more as it dries unevenly. In very humid offices, especially after weekends with the air conditioning off, jams become frequent.
How should printer paper be stored?
Keep paper in its original sealed wrapper until you need it, store reams flat in a dry room — not on the floor or against an outside wall — and only load as much as you’ll use that day. Keeping the print area around 45–55% relative humidity prevents most humidity-related jams.
Sources
- Library of Congress — Collections Care: how to care for books, paper, photographs and textiles
- US Environmental Protection Agency — Introduction to Indoor Air Quality
- ASHRAE — Standard 55: Thermal Environmental Conditions for Human Occupancy
Guidance from these bodies is general; figures for Sri Lanka come from our own reporting and DRYAir’s field experience.
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