Wednesday, November 22, 2006

Tony Talks -- A J Clark

Trouble Shooting Guide on Paper Problems for the Bookbinder

I was told that this issue of WT will focus on substrates – paper , board etc that get bonded together.
The paper upon which the book is produced is usually chosen by the publisher or book designer. The criteria is that it should be ideal for the printing equipment to be used and the print quality required. Unfortunately the best papers for printing are almost invariably the least favorable for adhesive binding.
The best paper to bind is fibrous, uncoated and fairly bulky – eg Newsprint, Antique Wove types. Short fibre - coated papers (such as art paper) do not bind, easily. This type of paper is difficult to bind with single roller gluing systems.
Testing for Paper Grain : There have been many discussions on the subject in the past, but just to recap on this as well as to understand more – The paper you intend to bind contains a grain, which is created by the flow of the pulp stock as it is suspended on the endless wire belt of the paper mill (machine)

Fig (2.1) Grain Direction

1. Pinch the paper between the fingernails
2. Draw lightly down the edge
3. There will be no stretch with grain but stretch mark across the grain

Fig 2.1 (cont)

Long Grain - This is cut lengthwise from the paper web so that the direction of grain runs parallel to longer side
Short Grain – is cut crosswise from the paper web so that the grain runs across the shorter side.

The best bind is obtained when the grain of paper runs parallel to the spine of the book. Cross grained paper can be only bound (as a last resort) provided the paper is fibrous and not too heavy (low gsm)


Given below are a few typical issues related to paper and the solutions.

Cocking or wavy edges - Over-dried paper will steadily increase its relative humidity, thus the problem will grow. Keep drying temperatures as low as possible; remoisten on the press.

Cracking at the fold - Over dried with intense heat, makes the coating medium brittle. Remoisten where possible or use a water line.

Fibre lift - Mechanical fibres that contain lignin expand under heat; this can give glossy papers a rougher surface. Keep drying temperatures low. Ask the buyer to choose wood-free paper.

Poor page strength - Good results one week, poor results the next and yet bound on the same machine, same adhesive and operator. Intense drying makes the fibres brittle, i.e. LWC paper is 50 per cent mechanical pulp and 50 per cent wood free. Brittleness in the ground wood can reduce the page flex and pull strength by half.

Stepping after trimming Over-dried and mixed paper stocks. Growth will vary in speed and amount due to the relevant humidity. Keep drying temperatures to a minimum, re-moisten on the press, and do not use mixed papers.


Wrinkles on Spine after the trimming operation –

Perfect Binding, if not perfect in all aspects is to deliver perfectly smooth spine. Wrinkles on book spine are caused due to many reasons, including the cover stock.
Spin crease - Spongy spine. Increase nip pressure on the binding machine. Check guillotine clamp pressure. Investigate the grinding angle of blade. Test for damp cover board due to aqueous links or varnishes. Monitor board de-lamination and test other boards on the same work.

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