A: There are the following types of paperboard for binding
(1) Off-white cardboard. Also known as book cover cardboard, it is a cardboard set for book covers made by the national industry.
(2) Grass cardboard. Also known as horse dung cardboard, the surface is rough and yellow in the early days of China.
(3) Yellow cardboard. One surface is smoky yellow (the same color as kraft paper, smooth, hard and rigid cardboard, often used to make binding envelopes and book covers
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