水分 and 乾燥: total weight and water content
Distinguish an object’s total weight from the 水分 within it. A statement that it was dried does not by itself give a remaining water content of exactly zero.
The object and its 水分
水分, read すいぶん, means moisture or water content. 研究室で野菜に含まれる水分を測った。 says that someone measured the water content of vegetables in a laboratory.
The measurement concerns the water contained in the vegetables. Do not change it into a statement about weighing the entire vegetables.
Removing water by squeezing
洗った布を軽く絞って水分を取った。 says that someone lightly squeezed the washed cloth to remove water. Read this as reducing its water content through light squeezing.
If a cloth weighing 100 grams in total is stated to contain 20 grams of water, its water content is 20 grams. The 100 grams includes the whole cloth and its water, not water alone.
Drying and the amount remaining
乾燥, read かんそう, means drying. 洗ったハーブを日陰で十分に乾燥させました。 says that someone thoroughly dried the washed herbs in the shade.
Distinguish sufficient drying from an exact measurement of remaining water. Do not insert a value of zero when the sentence supplies no such measured quantity.
If a cloth weighing 100 grams in total contains 20 grams of water, does its 水分 also weigh 100 grams?
Show the answer and why
No. Its stated water content is 20 grams. The 100 grams is the total weight of the cloth including the water.