The reasons and countermeasures of the back-folding and the cover-warping in bookbinding (II)

4 No matter what kind of craft brush the adhesive onto the back of the internal instrument, the adhesive will lose its fluidity while losing moisture. In the process of continuous curing, the distance between atoms is greatly shortened, and the internal stress generated by the adhesive causes the adhesive to gradually shrink in volume, and finally stabilizes in a volumetric shape that is smaller than that of the original brushing. Some adhesives can shrink up to 14%. Changes like Figure 1 occur.

Figure 3 1- Adhesives; 2-Insert album; 3-side glue; 4- cover

The change in the volume of the adhesive after drying shrinkage results in a change in the "opening" and the angle of the contact surface between the adhered cover and the book block. See Figure 2.

5 Because the thickness and the tightness of the paper are different, the thickness of the book block after the collation will be inconsistent. In the mechanical package book, due to the fact that the rules of the cover paper transportation have been fixed, misalignment will occur due to the different thicknesses of the book blocks, making it difficult for the book spine to be biased.

(to be continued)

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