Paper & Quality

Our papers are extremely versatile and they have to be as their properties have to meet a big number of requirements. Here, you will find noteworthy information on manufacturing techniques, quality characteristics, quality management and testing procedures.

How are genuine mould-made papers made?

This process is similar to traditional manual papermaking and produces the most valuable paper. Only papers produced on what is known as a ‘cylinder mould paper machine’ may be called ‘genuine mould-made papers’. Some papers have watermarks and the typical, irregular deckled edges as recognised quality characteristics.

Traditional paper production on the cylinder mould paper machine starts in the vat, in which a round mould rotates. At Hahnemühle, pure spring water and paper fibres as well as a few other ingredients are mixed in a highly diluted form inside the vat. The fibres are either rags (cotton fibres) or pulp. Read more about this in the article titled ‘Raw materials and properties of artist paper’. In the vat, a round mould cylinder rotates slowly and evenly. The paper is produced at the highest point of the mould cylinder. This is where the paper fibres settle in a disorderly fashion and combine to form a wet paper fleece. The disorganised fibres subsequently cause the colours to ‘flow’ in a wonderfully free and inspiring way on the real mould-made papers. During the paper production process, the water firstly flows through the mould and felts then take over the paper fleece, which is still very wet. The felts transport the paper further into the paper machine, give it the surface desired according to the grade on both the top and the bottom, and drain the paper. Watermarks can be applied to the cylinder mould or limitations for real mould-made paper produced in sheets. Both are sewn onto the mould cylinder with copper wire. In both cases, fewer fibres are deposited at this raised point on the mould. The paper is thinner there, light can shine through (at the watermark) or the paper can be torn at this point. A machine-made paper with four genuine deckled edges can also be produced in this way. How so? The paper is thinner at the dividing tear lines. Due to different feed speeds, the still-moist paper in the machine is torn at the thinner point. In addition to sheets, rolls can also be produced on the Hahnemühle cylinder mould paper machine. This genuine mould-made paper from the roll is subsequently cut and processed into painting pads in various artist sizes. The cylinder mould paper machine’s speed is comparatively slow, at just 4 m/min to 15 m/min. However, this traditional production process, which has a handcrafted character, guarantees the high quality requirements that the genuine mould-made paper is expected to meet. The cylinder mould paper machine can be used to make papers with grammages of between 80 g/m2 and 600 g/m2 – very thin to very sturdy artist papers – from light Ingres paper to heavy Leonardo watercolour board.

 

 

Papermaking on a Foudrinier Paper Machine

The fact that all the fibres are deposited in the machine’s running direction is characteristic of this production process. The flow behaviour of watercolour paints can be easily predicted and influenced on this paper.

The heart of the fourdrinier paper machine is a continuously rotating, flat plastic mould. The mixture of spring water and paper fibres flows evenly onto it. The water runs off through the mould, while the paper fibres are deposited in the machine’s running direction and bond to the paper on the mould. Felts also take over the further transport through the machine in the fourdrinier paper machine. The paper web runs over steam-heated cylinders between two felts. The paper web is dried and pressed. Hahnemühle felts – which are made of wool or mixed fabrics comprising synthetic fibres and wool – mark the paper’s surface with their characteristic texture. So you can rest assured that you’re always getting your favourite paper with the same texture.

Important: At Hahnemühle, the papers are felt-marked during the production process. Always look out for this feature of real artist papers as it guarantees the handcrafted character! Watercolour papers, which in contrast are embossed once production is complete, often appear inferior.

All papers from the fourdrinier paper machine are gently dried and smoothed, continuously checked and then wound. The paper machine runs at a speed of up to 105 m/min. Hahnemühle’s fourdrinier paper machine produces not only artist papers, but also filter papers and high-purity raw papers for use in medicine and industry.

Quality criteria

Due to the application purpose each paper has to meet special requriments. Learn what our papers make to become unique.