Paper surfaces – for watercolours
This week Jane starts to look in more detail at paper surfaces for different media. First up is paper for watercolours.
Following a previous article about paper and sketch books people were asking for more detail so here goes. Jane looks at the different surfaces, processes and makes of paper.
Cotton or wood pulp
In general, watercolour papers are made from one of two materials; cotton or wood pulp.
You can get 100% cotton papers, which are preferred by the professional artist, and offer the very best painting surface.
Wood pulp is also known as wood free paper and is made using a chemically treated pulp with the lignin removed. (According to the dictionary lignin is impure matter found in wood pulp). This paper is an inexpensive alternative to cotton paper and is a good choice for amateurs and beginners.
Watercolour paper is available in three different surfaces,
Hot Pressed (HP), Cold Pressed (NOT) and Rough.
These are available to purchase in single sheets, pads, rolls and blocks. Blocks are pads of watercolour paper that are pre stretched for you so you don’t have to stretch your paper before you start painting. They are gummed on all four sides leaving a small area to insert o palette knife to release the sheet when finished painting.
All watercolour papers are available in different weights for different purposes.
How the paper is made
Handmade papers tend to be made from 100% cotton and are very durable. They tend to have an irregular surface which some artists like, it also tends to be heavier than machine made watercolour papers and will not require stretching.
Mould made paper
Mould made paper is machine made, this consists of a stainless steel vat and cylinder mould, these are usually around 260cm in circumference and 130cm in width. A dilute mixture of pulp and water is pumped in to the vat. The mixture then forms a fibrous web on the cylinder mould. Then this fibrous web is pressed to varying degrees to form the different surfaces available.
Machine made paper
In this instance a flat machine is used where a slurry of fibres are filtered out on to a continuous loop to form thin sheets of a wet mixture. This is then pressed to remove excess water. Once as much water as possible has been removed in the press the paper is passed through a number of heated cylinders in order to remove more moisture and smoothed flat.
Other paper types
Acid free paper
Acid-free paper can be made from any cellulose fibre as long as the active acid pulp is eliminated during processing. Acid free paper is ideal for preserving documents and artwork for long periods.
100% cellulose paper
You see this on many watercolour pads and this is a special type of paper made with cellulose, which is a material that plants use to build their stems and leaves. The cellulose can be derived from many sources, but typically watercolour papers are made from the cellulose derived from cotton and wood pulp.
This paper is just like paper made from wood pulp, it can be recycled to lessen our impact on the environment and further reduce our reliance on trees. Bamboo also helps to reduce soil erosion.
Paper has been made from bamboo for hundreds of years. The commercial process uses actual bamboo canes for the pulp.
For example Hahnemuhle produce a bamboo paper and it is a natural white mixed media paper made from 90% bamboo fibre and 10% rag. This paper is suitable for watercolour, acrylic and pastel painting as well as for sketching and mixed media.