Pulping is the stage that converts raw fibrous material into a uniform water suspension ready for sheet forming. The quality of this suspension — its fibre length, concentration and degree of hydration — directly determines the paper's surface texture, weight and mechanical strength. In handmade papermaking using recycled materials, the choice of input fibre is the single largest variable.
Selecting the Source Material
Not all recycled fibrous material produces equivalent pulp. The most widely used inputs in traditional and contemporary hand-papermaking are linen rags, cotton rags, and hemp or flax plant residues. Each brings a different average fibre length and degree of lignin content to the process.
Linen and Cotton Rags
Linen rags — discarded linen fabric and worn clothing — contain predominantly cellulose fibres with a length between 25 mm and 40 mm. This length is well suited to forming strong, cohesive sheets. Cotton rags, including worn textile offcuts, have a slightly shorter average fibre and produce a softer surface. Both materials require soaking before beating to allow the fibres to absorb water and begin to separate.
At workshops associated with the Duszniki-Zdrój mill in Lower Silesia, cotton and linen rags have historically been the primary inputs. Rags are sorted by colour and fibre type before processing; mixed-colour inputs result in a grey-toned sheet unless bleaching is applied. The Polish Museum of Paper and Printing (Muzeum Papiernictwa) documents that this sorting practice was standard in regional mills from the 17th century onward.
Plant Fibre Residues
Straw, dried grass, reed and flax stalks can also be processed into pulp, though they require more aggressive preparation than rag-based inputs. Plant materials contain lignin and hemicellulose alongside cellulose; if these compounds are not removed or broken down, they contribute to yellowing over time and reduce the paper's stability. Alkaline cooking — simmering the material in a dilute solution of wood ash lye or soda ash — is the standard pre-treatment before beating.
Note on recycled office paper: Recycled printed paper is occasionally used in experimental hand-papermaking. It produces a short-fibre pulp that forms fragile sheets with limited wet strength. The ink and coating particles present in commercial paper also affect pulp colour. For structural papers, recycled printed paper is typically blended with rag pulp rather than used alone.
Retting and Soaking
Before mechanical beating begins, fibrous inputs are typically retted — soaked in water for a period ranging from several hours to several days, depending on the material. Retting softens the pectin that binds individual fibres together in plant-based materials, making separation easier during beating. Cotton and linen rags generally need only a thorough soaking of 12–24 hours to reach sufficient water uptake.
Water temperature during soaking influences bacterial activity in the vat. Some historical sources describe intentional fermentation of rag vats to accelerate fibre separation — a practice that produces a distinctive smell but reportedly yields a more even pulp. Contemporary workshops in Poland generally avoid extended fermentation in favour of mechanical beating with clean water, both for hygiene and for better process control.
Beating: The Core Pulping Step
Beating is the mechanical process that breaks fibrous material into individual cells and causes the cell walls to fray — a process called fibrillation. Fibrillated fibres bond more strongly with neighbouring fibres during sheet formation, producing a denser and more cohesive sheet.
Stamping Mills
The oldest mechanical pulping method uses wooden stamps or hammers lifted by a water wheel cam shaft and dropped repeatedly onto wet fibres in a stone trough. The stamping mill at Duszniki-Zdrój retains functional stamps driven by the mill's original water wheel mechanism. Each stamp cycle crushes and frays the fibres without cutting them, preserving long-fibre length — an advantage over later cutting-type beaters. Stamping is slow: a batch of rags sufficient for several hundred sheets may require six to ten hours of continuous stamping.
Hollander Beater
The Hollander beater, developed in the Netherlands in the late seventeenth century, replaced the stamping mill in most European mills within a generation. It uses a rotating drum with metal bars passing close to a bedplate to bruise and fray fibres in a circulating water channel. A Hollander reduces beating time to one to three hours per batch depending on fibre type and desired sheet character. However, the rotating drum also tends to cut fibres shorter than stamp beating, producing a slightly different surface quality.
Several hand-papermaking practitioners in Poland currently use tabletop or small-scale Hollander-type beaters for batch production. These compact units are commercially available from specialist suppliers in Germany, the United Kingdom and Japan.
Hand Beating
For very small batches, fibres can be beaten by hand using a wooden mallet on a stone slab or in a mortar. This method is used in educational workshops and for specialty papers where total control over fibre length is desired. It is physically demanding and limited in output.
Pulp Concentration and Vat Preparation
After beating, the resulting fibre mass is diluted with clean water to the working concentration used in the vat. For most handmade sheet weights, the working suspension contains between 0.3% and 0.8% fibre by dry weight — meaning roughly 3–8 grams of dry fibre per litre of water. A higher concentration produces a heavier, more opaque sheet; a lower concentration yields thinner, more translucent paper.
Before each dip of the mould, the vat contents are agitated to prevent fibres from settling unevenly on the screen. In traditional workshop practice, a wooden or metal rod is used to stir the vat in a circular motion immediately before each sheet is formed.
Additives at the Pulping Stage
Sizing agents — substances that reduce paper's absorbency — can be introduced either at the pulp stage (internal sizing) or applied to the finished sheet surface (surface sizing). Animal glue and starch are the two most common traditional internal sizing agents used in Polish hand-papermaking. They are dispersed in the pulp before vat filling. Alum is sometimes used as a precipitant to anchor sizing onto fibres, though it lowers the paper's long-term pH stability.
- Animal glue sizing: Reduces ink bleed and strengthens the sheet surface. Applied after sheet forming as a bath treatment or mixed directly into pulp.
- Starch sizing: Lighter sizing effect than gelatin; common in papers intended for printing rather than calligraphy.
- Alum (potassium aluminium sulphate): Historically paired with rosin to create an acid-sized paper. Acid sizing degrades cellulose over decades; archival papers now use neutral or alkaline sizing agents.
Storage of Prepared Pulp
Beaten and diluted pulp can be stored in sealed containers for several days at cool temperatures without significant fibre degradation. Longer storage requires keeping the pulp in near-anaerobic conditions to prevent mould growth. Adding a small quantity of calcium carbonate to the stored pulp maintains a neutral to slightly alkaline pH, which slows bacterial activity and improves the final paper's permanence.
In Polish conservation and restoration workshops, pre-beaten pulp is sometimes stored dried as a sheet or board ("dry pulp"), which can be re-hydrated and refined as needed. This allows pulp of known fibre composition to be prepared in batches and used over several weeks.
