Maintenance
3 ways Ontario winters dry paper, and what to change at the press
Winter paper drying Canada has three causes: cold outdoor air, indoor heating and forced-air circulation. Adjust paste, board handling and pressing time.
What to take away
- Winter paper drying Canada runs fast and unevenforced-air heat pulls moisture out of paste and boards faster than most binders expect.
- Aim for 40 to 50 percent relative humidity in the bench room, and keep the wet work area cooler than the press area.
- Paste dries from the edges inward under low humidity, so boards cup toward the pasted side unless you weight them early.
- Cover drying stacks with boards and weight, and check them sooner than you would in summer.
- Pressing times stretch in winterthin pasted sheets may need only a short nip, while laminated boards need longer under weight.
- Track temperature and humidity at the bench, not at the thermostat, because the two rooms can differ by several points.
Zone targets for a bindery through an Ontario winter:
| Zone | Relative humidity target | Temperature target | Why |
|---|---|---|---|
| Wet work and pasting | 45 to 55 percent | 18 to 20 C | Slows skinning and edge drying |
| Pressing and nipping | 40 to 50 percent | 20 to 22 C | Keeps boards from cupping under weight |
| Drying stack | 40 to 50 percent | 18 to 21 C | Even moisture loss across the stack |
| Storage and finished work | 35 to 45 percent | 18 to 22 C | Limits dimensional movement |
Why Ontario winters dry paper faster than makers expect
Ontario winters dry paper through three related mechanisms:
- Cold outdoor air holds little moisture.It brings little water vapor into the studio.
- Indoor heating lowers relative humidity.When cold air warms indoors, its relative humidity drops sharply. A studio that sits at 50 percent in October can fall to 20 percent in January without any change to the work.
- Forced-air furnaces circulate warm, dry air.That moving air carries moisture away from surfaces, including pasted boards on the bench.
Forced-air furnaces make it worse. They move warm, dry air across every surface, including pasted boards on the bench.
This is not a small effect. Binders in Ottawa, Toronto, Sudbury and Thunder Bay all report the same pattern: winter work dries faster, cocks more and needs earlier intervention. The fix is not to fight the climate but to control the microclimate around the press and the drying stack.
If your bench sits near a register, move it. A metre of distance changes the drying rate more than any paste recipe. For small studios, the answer sits in our notes on small-space layout for decorative paper: where the heat blows matters more than where the light falls.
Forced-air heat and low indoor humidity: what changes at the press
At the press, make three changes:
- Paste:Mix smaller wheat starch paste batches and keep them covered with a damp cloth; methyl cellulose holds water longer.
- Boards:Paste both faces where the board allows, then weight the work immediately and dry it under cover.
- Pressing:Give thin pasted sheets a short nip, but leave laminated boards under weight longer, often overnight.
Paste thickens as it sits. Wheat starch paste that flowed well in summer will skin over in minutes under a dry draft. Mix smaller batches and keep them covered with a damp cloth. If you use methyl cellulose, it holds water longer.
Boards move. A paste layer on one face adds moisture to that side, so the unpasted face loses moisture faster and the board cups toward the paste. The thicker the board and the wetter the paste, the stronger the pull.
Pressing time changes. A short nip under weight is enough for thin pasted sheets in dry air, but laminated boards need longer because the core holds moisture after the surface feels dry. Test with the back of your hand, not your fingertips.
The building itself matters. Energy efficiency for buildings - Natural Resources Canada covers how envelope and ventilation choices affect indoor moisture, which is useful when you plan a studio fit-out or argue for a humidifier. A tight, well-sealed room holds added moisture better than a drafty one.
Health and safety rules still apply when you add humidity and heat. CCOHS: Acts and Regulations set out the compliance framework for workshop conditions, and CCOHS: Physical covers the risks that come with damp floors, hot equipment and cramped pressing areas.
Humidistat targets for a bindery through an Ontario winter
A humidistat helps control room moisture. Set targets by zone, not by the whole studio, because wet work and pressing want different air. The zone table at the top of this article carries the numbers.
These are working targets, not standards. Adjust to your own stock and paste. Record readings twice a day for the first two weeks of cold weather, then weekly once the pattern is clear.
Keep a thermometer and hygrometer at bench height. Thermostat readings reflect the whole building, and a forced-air system can cycle humidity up and down several times an hour.
For supply purchases, GST/HST on bookbinding supplies in Canada is a separate planning consideration; humidity control at the bench starts with tracking conditions and protecting the drying stack.
Paste drying and board warping under winter conditions
Board warping winter is mostly a moisture gradient problem. One face gains water from paste, the other loses it to dry air. The board responds by curling toward the wet side.
The gradient forms fast in Ontario. Paste that would take twenty minutes to set in a humid autumn can skin in five under forced air. Once the surface skins, the core keeps drying slowly, and that slow loss pulls the board the other way overnight.
Counter it in three ways. First, paste both faces when the board allows it, so both sides gain and lose together. Second, weight the board immediately after pasting, before the edges dry. Third, let it dry slowly under cover rather than in open air.
Material choice matters too. For a related paper-arts project, see how to photograph and present paper marbling. A board that behaved all summer can fail in January without any change in technique.
Laminating is the hardest case. Two pasted faces trap moisture in the core, and dry air pulls it out through the edges. Expect more cupping than in summer and plan for longer under weight.
Covered drying stacks and pressing times that need adjusting
A covered drying stack slows moisture loss and evens it across the sheet. The cover is not there to seal the work in; it is there to slow the air at the surface.
Build the stack in layers. Start with a flat board, then blotter, then the pasted work, then blotter, then board. Repeat, and finish with a weighted board on top. Change the blotters after the first hour, then again the next morning.
For ten pasted sheets, a typical build is one base board, ten repeats of blotter, work, blotter, then a top board, with 5 to 10 kg of weight on top. Felt, boards or a small press all work.
Pressing times need adjusting in both directions. Thin pasted sheets can come out earlier than in summer because the surface dries fast. Laminated boards need longer, often overnight, because the core releases moisture slowly.
For winter layout, put the pressing bench on the still side of the room, away from registers and doorways, and keep the cutting bench near the light. Where space allows, two separate benches holds that split best.
For a small studio, a small bookbinding room still fits four zones: cutting, wet work, pressing and storage. Keep the drying stack in the storage zone, where the air is calmest and the humidity steadiest.
A winter paper drying Canada checklist for the bench
Run this at the start of cold weather and again after any cold snap.
- Check the hygrometer against a second unit and record the difference.
- Set the humidistat to the zone targets in the table above.
- Move the bench and drying stack away from registers and doorways.
- Mix smaller paste batches and keep them covered with a damp cloth.
- Cut blotters for the drying stack and keep a spare set ready.
- Change blotters after the first hour and again the next morning.
- Log pressing times for each job so you can compare with summer runs.
Bench steps for an Ontario winter, in order:
Winter paper drying checklist
- Read the hygrometer and thermometer at bench height before you start work.
- Adjust the humidistat and wait for the room to settle before pasting.
- Paste both faces where the board allows, and weight the work at once.
- Build the covered drying stack with fresh blotters and a weighted top board.
- Check the stack after one hour, swap blotters, and note how the edges feel.
- Leave laminated boards under weight overnight, then check for cupping before finishing.
- Record the result so next winter's pressing times start from a known point.
Posture and setup matter when you spend longer at the press. CCOHS: Ergonomic covers bench height, reach and repetition, which is worth reading before a long winter of heavier pressing.
Two habits carry most of the benefit. Keep the air still around the drying stack, and write down the morning hygrometer reading. Both cost nothing and both prevent most winter failures.
