The moment a freshly pulled sheet leaves the vat, the papermaker has already made most of the important decisions. Fibre choice, beating degree, and pulp concentration are fixed. What remains — pressing and drying — determines the surface character, dimensional stability, and eventual usability of the sheet.

In a heated studio in January in Winnipeg and in a humid August workshop in Halifax, the same pulp, pressed with the same equipment, will produce sheets with noticeably different surfaces and drying times. The methods described here are documented for conditions common to Canadian workshops, with notes on where ambient conditions require adjustment.

Couching: transferring the wet sheet

After pulling a sheet on the mould, the papermaker couches — rolls the wet sheet face-down onto an absorbent surface called a felt or a couching cloth. The mould is lifted away, leaving the sheet behind. This is the first stage of water removal.

Felts for couching are traditionally made from wool. A boiled wool felt in the 400–600 gsm range absorbs water efficiently and releases the dried sheet cleanly. Cheaper synthetic alternatives — polyester craft felt — absorb less water and tend to leave a compressed texture on the sheet surface where fibre contact is uneven.

The technique matters: the mould contacts the felt surface at one edge and rocks forward, pressing out air and establishing contact progressively across the sheet rather than all at once. Pressing straight down traps air bubbles, which appear as holes in the finished sheet.

Post — the stack of alternating felts and wet sheets — is assembled until the pressing stage. Each new sheet is couched directly onto the felt covering the previous sheet. A typical small-batch post contains 8–12 sheets. More than 20 sheets risks uneven pressure distribution during pressing.

Pressing: removing bulk water

Pressing removes the majority of the water from the post. The goal is to apply even, sustained pressure without introducing surface texture from the pressing equipment itself.

Screw press

A traditional bookbinding or cider screw press applies controlled pressure incrementally. After loading the post, the screw is tightened gradually over 10–15 minutes. Sudden application of full pressure can shift wet sheets sideways, tearing or distorting them. Once pressure is applied, the press can be re-tightened as water releases and the post height decreases. A typical pressing cycle lasts 30–45 minutes.

Water expelled during pressing should drain freely. Elevating the press on a slotted board or placing a tray below the base collects the drainage without allowing the post to sit in pooled water, which slows removal and re-wets the lower sheets.

Hydraulic press

Studio hydraulic presses apply 1–3 tonnes of force across the post. This removes more water than a screw press and allows the sheets to dry faster. The tradeoff is that excessive pressure can permanently compress the sheet, closing the surface and reducing absorbency — a problem if the finished paper is intended for writing or printing.

Pressing pressure of 0.5–1 bar across the sheet surface is a reliable starting range. Sheets pressed at higher pressures develop a surface more suited to graphite drawing than to ink-based work.

Cold pressing without a dedicated press

Two flat boards and a stack of heavy objects — books, concrete blocks, or filled water containers — provide adequate pressing force for small batches. Place the post between two plywood panels of at least 18 mm thickness to distribute weight evenly, and load weight gradually over 30 minutes. This method produces results indistinguishable from a screw press for sheets up to A4 size, and requires no capital equipment.

Parting the post

After pressing, the sheets are separated from the felts — a step called parting. A partially dried sheet lifts from the felt with gentle peeling from one corner. A sheet that tears during parting is either over-pressed (fibres have compacted and bonded to the felt surface) or under-pressed (too wet to hold its structure independently).

The order of parting matters: remove outer sheets first, working toward the centre. Central sheets in a deep post tend to receive the most pressure and may adhere more firmly to the felts.

Drying methods compared

Free air drying (restrained)

Sheets dried unrestrained on a flat surface curl as they dry, because the surface exposed to air loses moisture faster than the underside. Restraining the sheet eliminates most of this curl. Two approaches work well:

  • Board drying: The wet sheet is adhered to a smooth wooden or Formica board by pressing it flat with a sponge or roller. As it dries, the edge adhesion keeps the sheet flat. Once fully dry, the sheet releases from the board with a thin palette knife or by slightly flexing the board. This method produces a smooth surface on the board-contact side and a natural texture on the exposed side.
  • Spun drying between boards: Two boards sandwich the sheet, which is held flat by the weight of the upper board. The boards must be dry and flat. As the sheet releases water into the board surface, the boards themselves must be rotated and dried periodically.

Drying in Canadian winter conditions

Indoor heating in Canadian winter reduces relative humidity to 20–35% in most homes. Handmade paper dries to equilibrium moisture content of 4–6% at these conditions, which is somewhat lower than the 6–8% typical in European humid winters. The sheet reaches its final dimensions faster, but the rapid drying can introduce internal stress in thick sheets made from long-fibre materials like nettle or flax.

For thick sheets (over 120 gsm) in winter conditions, a slightly slower drying environment — a bathroom with a shower run briefly before drying begins — raises ambient humidity enough to reduce cracking risk without meaningfully extending drying time.

Drying in summer

In coastal British Columbia or the Maritime provinces in summer, outdoor humidity can exceed 80%. Sheets dried in these conditions take 24–48 hours to reach usable moisture content, compared to 4–8 hours in a heated interior space. Mould growth can develop on sheets left in humid, stagnant air for more than 36 hours. Air circulation — a fan directed across the drying surface, not at the sheets — reduces this risk without introducing the distortion caused by direct airflow on wet fibre.

Surface effects and sizing

Freshly dried, unsized paper has a highly absorbent surface. A droplet of water applied to an unsized sheet spreads and feathers within seconds. This is the natural state of the cellulose network — the fibres pull water in by capillary action.

Sizing reduces this absorbency. Gelatin sizing — a dilute solution of leaf gelatin (1–2% concentration) applied warm by brush or dip — is the traditional method. The gelatin fills the spaces between surface fibres and, after drying, reduces water uptake by approximately 70%.

For archival applications, methyl cellulose sizing is neutral in pH and does not introduce the organic material present in gelatin, which can attract insects in storage. It is also more consistent in application, as gelatin viscosity changes with temperature.

A consistent pressing routine and a humidity-aware drying approach produce sheets that behave predictably in bookbinding work. Sheets of variable moisture content change dimensions at different rates after binding, which causes text blocks to warp.

The relationship between the pressing stage and the finished sheet is direct. Understanding what each method does — and does not — remove makes it easier to work backward from the intended use of the sheet to the appropriate process.