by Edward H. Snider
This time we will discuss preparing the pulp and start to describe how handmade paper is made.
Making Paper by Hand: Up until the papermachine was invented by Nicolas Louis Robert and patented in 1799 all paper had been made by hand 1. Today there exist very few commercial mills in Europe and the Americas where paper is still made by hand, and these are usually associated either with museums or with small family businesses making high quality specialty papers. In Asia and the Far East there are more small family businesses but these, too, are declining rapidly in numbers.
Handmade Papermaking Methods: There are two major handmade papermaking methods. These are called Western or European, and Oriental or Japanese. At Cranberry Mills only the Western method is used and this method will be described here.
Pulping: In a non-integrated handmade papermill dry sheets of pulp are bought from a pulp mill in as large as 200+ kg bales. This is mixed with water and broken up into a fiber suspension with extreme agitation at a consistency (% solids) of one to two percent either in a hydropulper or directly in a Hollander beater.
Pulp Additives: After the pulp to be used for papermaking has been beaten to the desired degree of hydration, as measured by a Canadian Standard Freeness, a Schopper-Riegler Tester or a Drainage Tester 2, several additives may be mixed with it while under agitation in the pulper or beater.
For archival papers, in order to counteract the effect of ambient acid gases such as sulphur dioxide (SO2) which may be present in the air in which the paper is stored or used, a buffer such as magnesium carbonate (MgCO3) or calcium carbonate (CaCO3) in powder form is added to the pulp.
For calligraphy, stationery, printing, printmaking and watercolor art paper grades, a neutral internal size is also added.
For facial tissues, towels, wipes, tea bags, filter papers, etc., a wet strength additive will also be required.
If the paper is to be colored, a pH neutral pigment must be used. In order to bond it to cellulose fibers, a neutral retention aid must first be added. For added whiteness and higher paper opacity, fillers such as titanium dioxide, kaolin or talc may also be added.
For non-archival colored papers, substantive organic dyes, or dyes requiring a mordant to bind them to the fibers may be used.
Screening the Pulp Furnish: Before transferring the pulp to the vat it may be screened to remove foreign materials. This is usually accomplished in large commercial handmade papermills by passing the diluted pulp through a stainless steel slotted flat screen. Passage of the fibers through the screen is facilitated by a vibrating diaphragm located under the screen.
The disadvantages of this equipment are that it is an expensive machine and that the pulp must be rethickened prior to its entering the vat. A screen would also remove any artistic inclusions, such as flower petals and grasses, etc., and so would have to be by-passed while making such grades of paper.
The Vat: After preparation, the pulp is transferred from the pulping vessel or beater to the vat, where its consistency (percent solids) is adjusted to 0.5 to 1.0%, depending on the paper basis weight (pounds per ream) or grammage (grams per square meter) required.
The vat is a tub which is made large enough to easily accommodate the size of the papermaking mould being used. At Cranberry Mills we have four different sized vats which provide for considerable process flexibility. The vat is set up at a height that is comfortable for the papermaker when he or she bends over it to introduce the mould.
The beaten pulp is heavier than water, and it will quickly settle to the bottom of the vat. To prevent this in large commercial handmade paper mills, the vat has a mechanically driven rotating stirring mechanism called "The Hog" 3 which extends across the bottom of the vat to keep the pulp from settling. In small mills like ours, a child's canoe paddle is used to stir the pulp in the vat just before introducing the mould.
Next time we will tell how handmade paper is formed using mould and deckle, and how it is wet pressed, dried and finished.
Don't forget to send your questions in the the Editor.