If you are anything like me watercolour paper has always been a bit of a mystery. Hot press vs cold press, 140 lb vs 300lb, pad vs block???? It’s like another language. Well today we are going to go through each of the relevant attributes one by one to help us all understand this mysterious medium and make sure that we are buying and using the correct product.
Most watercolour paper is made up of cotton, cellulose, or a combination of both. Cotton is the highest quality and the most archival. Cellulose is used in mid grade or student quality paper. These papers are typically acidic and therefore not archival.
Watercolour paper is made in three ways.
Handmade - self explanatory and the highest quality.
Mould-made - this closely resembles handmade due to the random arrangement of the fibres, but is actually made by machine, generally good quality and very durable.
Machine made – made in high volume machines so the price is good, but made mostly of cellulose and is less durable.
There are three surfaces that watercolour paper is available in.
Cold pressed - this is the most popular surface for watercolour and mixed media. It has a slight texture which absorbs paint and wet media well and is easily workable. This paper is also great for pastel, charcoal, ink, drawing, and mixed media.
Rough - this surface has a distinct texture to it as the fibres have been allowed to air dry without any smoothing. This finish is great for bold expressionistic work and textured subjects like rocks and trees, but not for fine detail.
Hot press - This paper is basically ironed to make it extremely smooth. The surface is therefore less absorbent than the other two. This paper is excellent for detailed paintings.
The weight of any paper, including watercolour, is a term to denote its thickness, and is expressed most often in North America in pounds. This is found by weighing a ream of paper (usually 500 sheets) of a determined size. For example, if a ream of 500 sheets measured at 22x30” will weigh 300lb, making it a 300lb paper. The higher the number the thicker and stiffer the paper is. There are generally three standard sizes for watercolour paper: 90lb, 140lb, and 300lb. The 90lb and 140lb can buckle when wet, making it necessary to pre-stretch the paper. 300lb on the other hand will accept more water and are less likely to buckle, while better withstanding lifting, reworking and general handling.
Sizing is an additive that is added to watercolour paper to make it less absorbent, thereby allowing the colours painted onto it to become richer rather than just soaking into the paper. Sizing can be internal, external or both. Internally sized paper has the additive mixed in throughout the fibres and is generally found in machine made paper. Externally sized paper has the additive added after the fact and is generally found in hand made paper. Using a paper that is both internally and externally sized will allow for more reworking while still keeping the colours rich. Do not soak paper that is only surfaced sized as one of our customers recently discovered. Externally sized paper will disintegrate when submerged in water.
There are generally three ways that watercolour paper is sold. Pads, blocks, and sheets.
Pads - Just like a normal pad of paper glued on one edge to keep the papers together. These are available in a variety of sizes. Great for travelling and working out of doors, but if the paper is of a lighter weight the pages will have to be removed and stretched if necessary.
Blocks - These are like a pad, but instead glued on all four edges to eliminate the need for stretching regardless of the weight.
Sheets - Again these are available in a variety of sizes, weights, and finishes.
There you have it, watercolour paper in a nutshell. Based on this knowledge and the project you have in mind you should be able to start your masterpiece off on the right medium.