Groundwood pulp or mechanical wood pulp was only suitable as raw material for the rougher paper types, and rag pulp still had to be mixed in as binding agent. As early as the mid-1800s, a chemical method of manufacturing wood pulp had been under development in various parts of the world. The first method to be applied, the so-called natron method, succeeded in detaching fibres from wood in such a way that the resultant pulp was more like rag pulp in character than mechanically ground pulp.

Finland's first pulp mill operated in the parish of Nurmi in 1876 - 1880 and used the so-called Sinclair soda method. In 1880, the Valkeakoski pulp mill started up and replaced the outdated soda method in 1886 with the sulphate method developed by C.F. Dahl in Germany. The real breakthrough in pulp manufacture, however, was the sulphite method invented by the American Benjamin C. Tilghman. It enabled paper manufacture from cellulose alone, or cellulose combined with mechanical pulp, depending on the paper quality desired.

The first sulphite cellulose factory in Finland was set up in Nokia in 1886. In 1872 and 1887, Kuusankoski and Kymi sulphite factories began operation, and Jämsänkoski in 1888. The mills used spruce as raw material. The cooking solution was made of lime and sulphuric acid. The resultant pulp was reasonably light in colour and suitable as raw material for many paper qualities even without bleaching. For this reason, sulphite pulp was the more popular method right up to the 1930s. The most important byproduct of sulphite cellulose production in the 1900s was sulphite spirit.

The sulphate factories used mainly pine as raw material; pulp wood unsuitable for sawmills and sawing waste. Sulphate pulp was brown in colour, when unbleached. Brown pulp was unsuitable for many applications, and in the early stages there were no effective means of bleaching it. Cooking byproducts were turpentine, methanol and pine oil, which was processed to make e.g. soft pine soap.