8K and 16K indicate the paper size of the sketch white sketchbook.

The size of sketch paper du is called the format. The calculation format is based on the whole sheet of paper. The number of small sheets cut and folded on each whole sheet of paper is called the number of copies. In our country, it is customary to name it according to geometry. The whole paper is half open, then half open, then half open, half open, half open, half open, half open, and so on.
Full open (781×1086mm), half open (530×760mm), 3 open 362×781mm, 4 open 390×543mm, 6 open 362×390mm, 8 open

271×390mm, 16 open 195×271mm, 32 open 130×184mm.

The sketch paper is smooth on one side and rough on the other. The rough side is the positive side. Usually we choose to paint on the front, but sometimes we also paint on the back for special effects. Here we choose to draw from the front, or sometimes from the back for special effects.

The way to tell the difference is to touch with your finger, let the light shine on it, and use a pencil to draw on both sides of the paper, finding the more curved side; There's also origami with coins, with clear lines in the front, but coins leave a mark, so try not to use this method.