Why Is My Handmade Paper Thicker on One Side (Thin Spots and Holes)?

Hold the sheet up to a window or a lamp. A good sheet shows an even texture of light and fibre. This problem looks different: one side is denser than the other, or there are pale patches, or there are small bare holes.

Three patterns are worth separating.

• A wedge. Thick on one side, thin on the other. This usually comes from the level of the mould.
• A patch. A thin or thick area in the same place on every sheet. Suspect the screen.
• A hole. A spot with no fibre at all. Check the screen and the water coming off the mould.

Look-alikes matter here. Cloudy, clumpy areas are a formation problem. Small craters that appear after the lift are often drips rather than thin spots.

Change one thing per pull, and compare each sheet with the one before it. Hold each to the same light.

1. Stir and wait. Stir the vat thoroughly and wait a few seconds for the eddies to die down. Pull a sheet. If it improves, the pulp had settled.
2. Level the mould. Pull another with a deliberate pause at level, or rest it on the edge of the vat as it drains. If the wedge goes away, the mould was tilting.
3. Mark the thin spot. Note where it falls on three sheets. If it does not move, take the deckle off and inspect the screen.
4. Lay a straightedge across the empty screen. A gap in the middle means a sag. See the sagging screen guide.
5. Compare first and last sheets. If the difference grows through the session, the vat needs more pulp.
6. Try a thicker vat. Add pulp and see if small holes disappear. If they stay in the same place, the holes are in the screen or under it.

Level as soon as the mould clears the water

Ted Snider's instruction is to level the mould immediately after lifting so the pulp stays inside the deckle. Then rest the mould on the front edge of the vat and a back board while the sheet sets, which keeps the level and lets water drain back in.

If you have no back board, a small level set on the mould for a few pulls shows whether you are holding it level.

Stir before every pull

Pulp settles. Catherine Nash notes that it tends to settle to the bottom and needs to be suspended just before sheet forming, and May Babcock's instructions also start with a stir. Snider adds a detail that beginners skip: stir just before forming, then wait a few seconds until the eddies have died down.

Dip and scoop the same way each time

Hold the mould and deckle together. Babcock dips them at a 45 degree angle to the bottom of the vat and scoops up, holding them horizontally. Snider scoops the mould forward while raising it, and levels it at once so the deckle holds the pulp in. Papertrail notes that a screen held tight to the deckle keeps pulp from running between the deckle and the screen.

Shake while the water is still shiny

Use short, jerky movements, side to side and front to back. Stop when the free water has gone. Snider notes that after that point, more shaking can no longer improve the sheet.

Correct the screen

If the thin or thick area stays in the same place, re-tighten or support the screen. Mary Tasillo notes that larger moulds need extra support behind the screening, and suggests plastic egg crate cut to size and glued directly beneath it. Papertrail's ribbed moulds use ribs about two inches apart to support the screen and keep it tight to the deckle.

Keep the vat charged

Snider puts a typical vat at 0.5 to 1.0% solids, and every sheet removes fibre. Top up with fresh pulp every three or four sheets, depending on vat size.

Check for holes in the screen itself by holding the bare mould up to the light. Repair any tear before you make another sheet.

• Stir and pause before every sheet.
• Set up the vat so the mould can rest at level while it drains.
• Add pulp on a schedule, and note it on your batch log.
• Check the screen at the start of the session.
• Pull at the same speed and the same depth each time.

A sheet with a thin wedge or a bad patch can be dropped back into the vat before you couch it. Take the deckle off, turn the mould over, and slap it flat onto the surface of the vat. Stir and pull again. It costs almost nothing.

Once a thin area has been pressed and dried, it stays thin. A thin spot cannot be added to afterward. If the sheet is important, re-pulp it.

A screen that is torn or a frame that has twisted out of true will keep producing the same defect. Rebuild the mould or replace it. Tightening cannot fix a warped frame.