As an experienced person, I was ignorant at first. In fact, the weight of sketch paper is different, that is, it weighs 80 grams per square meter (which can also be said to be sketch paper), 100, 140, 160, 180, but if you sketch, there are also 65500. There are more and more brands of sketch paper, and many people are confused about it. Now "Daqian" is a good brand of sketch paper in China and abroad, but it is relatively expensive and cost-effective. As for the early, middle and late stages you mentioned above, it may be that many people have different requirements for paper. There are also many kinds of "Daqian" brand sketch paper, and different people can choose by themselves.