This information is reprinted from the Cranberry Corner column of Hand Papermaking Newsletter #56 (October, 2001).
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Wet Sheet Handling / Drying
WET SHEET HANDLING. The “post” that has been eased from the press onto a waiting dolly consists of a pile of alternating press felts and sheets of wet handmade paper sitting on the bottom press board.
After wet pressing, the sheets of paper still contain over 65% water and are very fragile. The slightest touch with a finger or thumb will leave a permanent impression on a heavy, wet sheet of paper.
However the corners of small, light-weight sheets, up to about 8”x11” (22cmx28cm), can be teased up from the press felt using a stainless steel spatula, and the wet sheets gently lifted by hand and moved to the drying loft, without damaging the paper.
To handle 12”x18” (30cmx46cm) and larger (and heavier) wet sheets I use a pair of padded kitchen pot holders onto one side of each of which is stitched a layer of thin, soft sponge plastic. After teasing up the two front corners of the wet sheet of paper, the pot holders are partly slipped under the corners of the paper. The pot holders are then gently closed on the paper using both hands and the paper is carefully stripped off the press felt, lifted up and carried to and draped over the drying rack. The padding of the pot holders and the sponge plastic sheets prevent finger and thumb prints from leaving an impression in the wet paper.
LOFT DRYING. In old time handmade paper mills the wet sheets of handmade paper were dried by laying them out by hand on flat canvas blankets suspended in the loft tower of the mill where they were dried by the natural passage of air through vents in the walls, supplemented by steam heated hot air rising from below.1
Similarly I “loft dry” small sheets on 30”x60” (76cmx152cm) horizontal sliding wooden frame shelves across which nylon “fly” screen is stretched. These shelves are stacked ten high about six inches apart in a bolted angle steel frame.
During loft drying the top side of the paper dries more quickly than the bottom side which lies against the support blanket or screen. Since paper fibres shrink when they dry, this causes the top side of the sheet to shrink faster than the bottom side, and the sheet curls upwards. To minimize this, the sheets may be turned over when they are half dry. After drying, the sheets are stacked carefully and dry pressed overnight in the big 30-ton press. They come out flat!
ROPE OR PIPE DRYING. Another technique used is to drape the wet sheets over “clothes lines” or suspended pipes and air dry them. When the paper has dried, this method leaves a sharpish bend in the paper where the rope or pipe is located which is difficult to press out. Light-weight papers can be hung in “spurs” of wet sheets several layers thick.2
Instead of suspended ropes I use six 4” (10cm) diameter white PVC unperforated drain tiles mounted on three 1”x2” cross bars which in turn are mounted on a 2”x2” (5cmx5cm) vertical post, like a Christmas tree. The tiles are sawn to a length that is about 2” (5cm) longer that the widest sheet to be dried, and their support bars are spaced vertically to permit easy access when draping the wet paper.
A metal hook is fastened to the top of the support post which permits the “drying tree” to be hung up on a rafter of the drying room. Since each drying tree holds six large sheets of paper, several such trees are required to dry a post of paper.
When the sheets have been dried in this manner they have a smooth bend in them from the tiles that is much more easy to press out than when ropes or pipes are used. Heavy-weight sheets may take four or five days to air dry.
FORCED AIR RESTRAINT DRYING. This drying method entails the used of a stack of large size double- or triple-wall corrugated paperboard sheets.
On top of the bottom corrugated board, which sits on a table, is placed a plain, flat finished blotter that is larger than the dimensions of the sheet of paper to be dried.
The wet sheet of paper is removed from the press felt, as described above, and carefully laid and centered on the blotter. Then, a second blotter is placed on top of the paper.
Another sheet of corrugated board is then placed on top of the blotter and the process is repeated until the entire post of wet paper has been placed in the stack.
A sheet of plywood is then placed on the top board and a weight is placed on it. This weight helps to flatten the wet paper and it, and the friction of the blotters, restrain the paper from shrinking during drying.
When the stack has been completed a large electric fan is placed on one side of, and close to, the stack which has been oriented so that air can be blown through the open flutes of the corrugated boards.
The fan is turned on and left to blow overnight. The moisture in the wet paper migrates into the blotters and then through the surfaces of the corrugated boards and evaporates into and is carried away by the air stream!
In the morning the paper is dry, flat, and has not shrunk.
1One Hundred and Fifty Years of Papermaking By Hand at Hayle Mill, Maidstone, England, by J. Barcham Green, limited edition, 1960. 2Papermaking as an Artistic Craft, by John Mason, Faber & Faber, London, 1959.