Why Is My Handmade Paper Wavy or Cockled After Drying?

The sheet is dry, but it will not lie flat. The surface rolls in waves or small puckers across the page, sometimes all over and sometimes in one area.

That is cockling. Lay the sheet on a table and look at it from the side. A cockled sheet rises and falls across its face.

If the middle is flat and only the edges lift or roll, that is a different pattern. Go to the guide on curling edges, because the check comes out differently.

Some cockle is normal in air-dried handmade paper, and some papermakers want it. It only counts as a fault when you need a flat sheet.

Change one thing per sheet or per stack. Use sheets from the same post so the pulp stays constant.

1. Identify the drying method. Rack, table, line, cloth, or board. If nothing held the sheet flat, that is the most likely cause.
2. Try restraint on one sheet. Dry it between blotters under a board and weight, next to one dried the usual way.
3. Look for one-sided patterns. If waves collect on the side nearest a window, fan, or heater, the air is uneven. Turn the stack or the rack and see whether the pattern moves with it.
4. Think about the peel. If you take sheets off interfacing before they are dry, leave one on until it is fully dry and compare.
5. Only then look at the pulp. Compare your usual pulp against a shorter beat or a less shrinky fibre, dried in the same way.

Dry under weight

Exchange drying is the simplest restraint method for a home studio. Interleave pressed sheets with absorbent material such as blotters, towels, or newspaper. Put a board and a heavy weight on top.

Swap the damp layers for dry ones daily. Helen Hiebert notes that sheets can mould if the absorbent layers are left in place. Conservation practice is similar: layers are changed about four times at increasing intervals.

Test any interleaving material first to make sure it will not stain the paper.

Adhere the sheet to a board

Brush a partly pressed sheet onto a smooth board, window, or Formica surface. Work from the center outward with a brayer or wide brush so you do not trap air. Keep the edges well adhered.

Press the sheet only partly. Hiebert notes that fully pressed sheets do not adhere well. Outdoors, she starts board-dried sheets in the shade and moves them into the sun once they are somewhat dry, so they dry slowly and stay on the board. Mary Tasillo recommends untreated boards rather than boards coated with polyurethane, which paper tends to stick to.

Even out the air

Point fans across the broad faces of the sheets, not at the edges. In loft drying, stacks of four to six sheets, called spurs, limit cockling.

Conservation guidance for unrestrained drying is to dry slowly and evenly, to keep distortion down.

Leave the sheet on its cloth until dry

Removing damp sheets from interfacing tends to increase cockling. If you dry on pellon or cloth, wait until the sheet is fully dry before you peel it off.

Adjust the fibre or the beat

Long-beaten abaca and flax can shrink strongly. Marilyn Sward says sheets of long-beaten high-shrinkage abaca can look like a potato chip on a flat surface. Timothy Barrett notes that increased beating time tends to produce a paper prone to higher shrinkage. If you want a flat sheet from a shrinky pulp, use firm restraint or shorten the beating time.

• Decide before you press how the batch will dry, and set up the blotters and weights first.
• Turn sheets over about halfway through loft drying. Snider notes that the top surface dries faster and pulls upward.
• Keep drying layers dry. Change them daily and write that on your batch log.
• Use the same fibre and beat when flatness matters.

Most cockled sheets can be improved by misting and pressing. Hiebert notes that sheets which cockle a lot may need moistening with a spray mister before they are pressed again. For a long-beaten, high-shrinkage sheet, Sward's answer was to dry it over an armature with methyl cellulose rather than flat. Accept some waviness, or re-pulp the sheet and dry the next one under restraint.

Do not iron a wavy sheet in the hope of a quick fix. Make: notes that ironing speeds drying but tends to cause more cockling.