Saddle-Stitched Programmes: Wire, Fold and Creep

A 64 page programme on 100 gsm text stock creeps about 3.2 mm at the foot, so the fore edge of the innermost spread sits roughly 3 mm further in than the cover. On a short run you compensate by shingling the sections on the saddle, not by trimming more. The fold must land on the spine line of the cover, and the wire has to be long enough to pass through the thickest point of the book and clinch on the inside. If you are commissioning saddle-stitched programmes for a season, the numbers below are the ones the bindery will ask you for.

We run theatre work in small batches, and the printed programme is the piece that gets judged by hand in a lobby. It is also the piece most often ordered late.

How much creep on a 64 page programme?

Creep, also called push-out or shingling, is the amount by which the inner spreads extend beyond the outer ones once the book is folded and stitched. It exists because the paper has thickness. A folded signature is not a line; it is a stack of half-sheets pivoting around the spine.

The arithmetic is simple. Take the number of leaves in the book, divide by two to get the number of nested spreads, multiply by the caliper of one leaf, and multiply by pi over two, roughly 1.57. For a 64 page programme on 100 gsm uncoated text, one leaf measures about 0.10 mm. That gives 32 spreads, so 32 x 0.10 x 1.57 = 5.0 mm of total creep at the fore edge. In practice the outer cover takes up part of that, and the visible push-out at the foot of the innermost spread is closer to 3.2 mm.

On coated stock the caliper is higher for the same grammage, and creep grows with it. A 150 gsm gloss text at 0.13 mm per leaf pushes the figure to about 6.5 mm. That is enough to throw a page number off the trim.

Two things follow. First, the creep is not an error; it is geometry. Second, you either design around it or you shingle it out.

Where must the fold land on a saddle?

The fold lands on the spine line of the cover, and the spine line is the centre of the flat sheet minus nothing. On a saddle stitcher the cover is draped over the saddle, the sections drop inside it, and the stitching head drives wire through the whole assembly at the lowest point of the saddle. That lowest point is the fold.

What matters is registration between the fold of the cover and the fold of the sections. If the cover is folded 1 mm off centre, every inner section shifts with it, and the trim on one side of the book will be 1 mm wider than the other. On a 210 x 297 mm programme that is visible when you fan the pages.

We check the fold by laying the folded book on the trimmer bed and measuring from the spine to the fore edge at head and foot. A difference of more than 0.5 mm between the two ends means the cover was not square to the saddle. The fix is at the folder, not the trimmer.

For a 64 page programme the sections are usually 16 pages each, four of them nested. Each section folds independently, and each fold has to sit on the same spine line. A section folded 0.3 mm long will show as a stepped fore edge after trimming.

Which wire gauge for a heavy cover?

Wire gauge is chosen by the total thickness of the book at the spine, not by the weight of the cover alone. The standard bindery rule is that the wire must be long enough to pass through the assembled book, turn over on the inside, and clinch with a leg length of about 2.5 to 3 mm.

For a programme with a 250 gsm cover and 64 pages of 100 gsm text, the spine thickness at the fold is roughly 4.5 mm. That calls for 24 gauge wire, which is 0.51 mm in diameter, with a leg length of 4.5 to 5 mm. For a lighter job, a 32 page programme with a 200 gsm cover, 26 gauge at 0.45 mm with a 3.5 mm leg is enough.

The common mistake is to specify 26 gauge because it looks neater and then discover that the clinch does not close on a thick spine. An open clinch means the wire pulls through the cover on the first opening. The other mistake is 22 gauge on a thin book, which crushes the spine and leaves a visible ridge on the inside of the centre spread.

We keep 24 and 26 gauge in the shop and order 22 only when the spine exceeds 6 mm. The wire is round, not flat, and it is cut to length by the stitcher head. Leg length is set on the machine, not ordered by the metre.

Shingling on a short run

Shingling is the compensation for creep. On a long run the sections are trimmed after folding, and the trimmer takes the fore edge down to a common line. On a short run of 200 to 500 programmes, the same operation is done by hand or on a small guillotine, and the shingling is set at the folder.

Shingling means that each successive section is pushed in by a fraction of the creep. For a 64 page programme with 3.2 mm of visible creep, the four 16 page sections are offset by roughly 0.8 mm each. The outer section sits furthest out, the inner section furthest in. When the book is folded and stitched, the fore edges line up and the trim removes a uniform 3 mm from the front.

If you do not shingle, the trimmer has to cut deeper to reach the innermost spread, and the outer pages lose margin. On a 64 page programme that can mean 6 mm off the fore edge instead of 3 mm, which eats into the text block.

We set shingling on the folder by adjusting the fold rollers and the delivery tape, and we check it by folding one sample section and measuring the offset with a steel rule. It is a mechanical setting, not a design decision.

The trim that follows

After stitching, the book goes to the trimmer. The head and foot are trimmed first, then the fore edge. On a saddle-stitched programme the fore edge trim is the one that removes the creep.

A standard trim allowance for a 64 page programme is 3 mm at the fore edge, 3 mm at the head and 3 mm at the foot. That means the flat sheet must be 6 mm wider and 6 mm taller than the finished page size. For a 210 x 297 mm programme, the flat cover is 216 x 303 mm before folding.

If the creep is larger than the trim allowance, the innermost spread will be trimmed short and the page number will sit too close to the edge. The bindery will either increase the trim, which reduces the margin, or reject the job. On a short run there is no room for a second pass.

We measure the finished book at three points along the fore edge and record the variation. A variation of more than 0.5 mm across a 64 page programme means the shingling was uneven. That is a folder setting, and it is corrected before the next batch.

What we ask for on the order

When a theatre company sends a programme to the bindery, we need four numbers: finished page size, page count, cover grammage and text grammage. From those we calculate creep, wire gauge and trim allowance.

For a 64 page programme on 100 gsm text with a 250 gsm cover, the working figures are 3.2 mm of visible creep, 24 gauge wire with a 4.5 mm leg, and a 3 mm fore edge trim. The fold lands on the spine line of the cover, and the sections are shingled by 0.8 mm each.

Those numbers hold for a short run. They do not change because the run is short; they change because the paper does.