The Kraft Process of pulp paper making supersedes the earlier sulfite process.
Based on the invention of the recovery boiler, which allows pulping to take place as a closed-cycle system, the Kraft Process for pulp paper making becomes more efficient than other chemical processes. The recovery boiler collects the used chemicals, known as black and white liquors, and allows them to be reprocessed again and again. In this way, pulp paper becomes increasingly affordable to produce, while also increasing in strength and durability.
As noted by the National Park Service, "Chemical wood pulp papers tend to be slightly stronger than ground wood pulp papers and to have a greater life expectancy" (nps.gov). This new paper's strength comes from longer fibers, which allow it to be used for a variety of purposes including: fine writing paper, air filters, and surgical masks.
The Kraft process is still used regularly in paper manufacturing around the world.
“How to Preserve Acidic Wood Pulp Paper.” Conserve O Gram 19, no. 24 (2001): 1-4. nps.gov.