From fiber to paper

Wood fibers are the basic materials of paper. Adding water to it creates a kind of porridge: the pulp. To give paper the desired properties, it is most important to choice the raw materials/fibers. They often combine the different kinds of fibers/pulp. Then the raw materials have to be mixed in a certain ratio (the recipe).  Finally, additives also ensure the proper flow of the process, the correct formation of the paper sheet and ultimately the desired properties of the paper. The table below gives you an overview of possible additives. Further down the chain, when it comes to the recyclability of paper, these additives are determined. 

Some popular fillers include:

Kaolin or china clay
Makes paper more printable and promotes impermeability to light (opacity).

Gives paper a very smooth surface, high whiteness and hardness.

Titanium white (titanium dioxide)
Relatively expensive filler but is lightfast and gives high coverage.

Makes paper smooth and thin.