Why Is My Handmade Paper Sticking to the Mould?

You turn the mould over onto the felt, lift it, and some or all of the sheet comes up with the screen. The sheet is intact. It simply went the wrong way.

That matters, because the fix is different from the one for a tear. If the sheet ripped in two and half of it transferred, read the tear guide first. If the sheet left the mould cleanly and then refused to leave the felt later, the trouble is further down the line.

Couching works on a simple balance. A freshly drained sheet is mostly water, with little wet strength. It clings to the mesh well enough to stay put when you turn the mould over. It transfers because its grip on a saturated felt is stronger than its grip on the screen. Anything that weakens the felt's pull or strengthens the screen's will leave the sheet behind.

Change one thing per sheet. Pull the next sheet the same way each time, and stop as soon as it releases. Your last change is the cause.

1. Check the felt. Touch it just before you couch. If it feels only damp, or if one area is wetter than another, wet it evenly and couch again with no other change.
2. Check the roll. Watch the mould come down. If it lands flat, or if you ease off partway across, slow down and hold firm contact from the first edge to the last.
3. Check the cushion. If the felts lie on a hard, flat board, put a folded towel under them, as Catherine Nash does. Couch again.
4. Check the drain. If the sheet slides or falls when you turn the mould over, let the next one drain longer. Snider notes that enough water has to drain away to keep the sheet from falling off the mould.
5. Check the screen. Hold the empty mould up to a light and look for pulp packed into the mesh. Press the center with a finger. If it gives noticeably, go to the sagging screen guide.
6. Check the pulp. If you added anything to the vat, make one batch without it. Strong adhesives mixed into pulp can bond a sheet to the mould.

Wet the felt evenly

Ted Snider's rule is that the surface of the felt must be uniformly saturated just before couching. He uses an atomizing spray nozzle on a hose. The transfer works because the pull between the wet sheet and a flat, saturated felt is greater than the pull between the sheet and the screen.

Catherine Nash's beginner method dampens the felts and squeezes out the excess. Both appear in published practice. If your damp felt is losing sheets, Snider's saturated felt is the change to try.

Make the roll continuous

Set one long edge of the mould on the felt. Lower the mould in one motion, keep firm contact as it rocks across, and lift from the edge where you started. Paperslurry compares it to closing a door and opening it again.

Snider's version is the same: one continuous motion, with the mould in firm contact with the felt throughout.

Crown or cushion the couching surface

Snider couches onto a press board of marine plywood bent to bow upward, which presents a curved surface to the mould. Nash's simpler version is a dry towel folded in half under the felts, to cushion the rolling action and absorb excess water.

Sponge the back of the screen

Nash sponges the excess water out through the back of the screen before she lifts, then pulls up one edge to see whether the sheet is releasing. She notes that most papermakers skip this step.

Add water at the edge

If fibres cling as you lift, put the mould back down. Nash squeezes some water onto the back along one edge, preferably the edge that seemed most likely to release, and tries again. If that fails, she floods the back with about a quarter cup of water.

Do not use a hose for this. Helen Hiebert warns that water sprayed through the back of a mould can force fibre between the layers of mesh.

Clean the screen

Rinse the mould after every session. Helen Hiebert notes that pulp sticks to everything and is easiest to remove while still wet, and that the mould and deckle should dry out after use.

• Wet the felt the same way every time, and do it right before each couch.
• Couch at a set point in the drain. Paperslurry's cue is to let the water drain to a drip.
• Cut felts larger than the sheet so the whole sheet lands on wet felt. Snider's are about two inches larger in each direction.
• Rinse the mould at the end of each session and let it dry.
• Check screen tension now and then, and add support to a large or flexing mould. Papertrail's ribbed moulds use ribs about two inches apart under the screen, partly to allow more pressure when couching.
• Write down drain time and felt wetness in your batch log so a good sheet can be repeated.

A sheet that has been torn or smeared on the way off the mould cannot be saved as a sheet. Return it to the vat, stir, and pull again. Nothing is lost except a minute.

Lacour's notes on additives warn that a strong irreversible adhesive, or even a strong methyl cellulose solution, mixed into pulp could glue the paper to the mould and ruin both. Keep adhesive experiments away from your best mould.