: To ensure a smooth, high-durability surface, the wet sheets are pressed to remove excess water and then dried on boards.

: The strength of the paper comes from interweaving these fibers. A mold is used to scoop a thin layer of the slurry, allowing water to drain through a screen.

: To prevent ink from spreading and to add rigidity, paper can be "sized" with substances like animal glue, vegetable gums, or rosin. Writing a "Solid" Academic Paper

If you are writing a research paper, "solidity" refers to the strength of your arguments and the quality of your sources.

To create a durable, "solid" sheet of paper, you must focus on the preparation of pulp and the removal of water.

The History of Paper - American Forest and Paper Association