About Single Sheets of Watercolour Paper
It is generally recommended that paper under 250 gsm be stretched, but I have found that papers of 450 - 550 gsm will warp & buckle. My style of painting begins with large washes but if your style uses thicker paint you may not have problems with buckling on papers 450 - 550 gsm.
HP = Hot pressed or smooth paper has the smoothest surface tends to used by artists who work in fine subtle details such as botanical, watercolour & portrait artists. It is pressed between two hot rollers.
CP = Cold pressed or medium paper has a medium texture. Paint settles into the dimples & adds to the surface texture. It is pressed through cold rollers.
Rough paper is pressed between sheets of textured felt as it is drying. The heavier texture is shown in irregular colour effects as the paint settle in the dimples. This paper is for those who have a bolder style of work.
Sizing - Watercolour paper is usually sized with gelatin so paint wont sink into the grain. Internal sizing is when the gelatin is added to the paper pulp mixture before the paper pulp is spread out flat to dry. External sizing is when the completed sheets of paper are soaked in a gelatin bath. Internal sizing means the paper wont become more absorbent after scratching, sanding or heavily working the surface. The best quality papers are sized internally & externally. Poor student quality papers resist paint by forming bubbles. This is due to too much size, but can be fixed by soaking the paper in a bath & wiping with a sponge to reduce gelatin thickness.
If you care about the longevity of your artwork, then 100% cotton rag paper is the best quality as it will last many hundreds of years. This type of paper is much easier to work with & it can take a lot of re-working, erasing or sanding. The long fibres from cotton rags are stronger than wood fibre, & will not break down over time.
Cellulose paper is made from wood pulp which expands when it gets wet so it will distort.
Handmade paper fibres have random directions which makes it very strong & stable. It wont need stretching.
Mould made papers are not as strong as handmade but are very stable - in higher gsm, they wont warp, buckle or distort. It is made on a cylinder mould in a stainless steel vat. The pulp mix is pumped into the vat & forms a fibrous web on cylinder.
Machine made fibre runs in one direction which makes it tear & distort easily. This paper is student grade & will become brittle, break down, yellow & spotty sometimes surprisingly fast.
The Deckle Edge is the irregular edging that looks hand torn. Handmade paper has 4 decal sides, mould made has two decal sides, machine made has none.
Watercolour & Acrylic Painting Papers - Pads, Books, Sheets & Rolls
SEE Papers - Drawing Papers for - Art Spectrum Colourfix Pastel Paper 360 gsm which has a coloured gesso ground. It is ideal for acrylics, inks & watercolours. It has a tough toothy surface that take sanding, scrubbing & re-working.
SEE Surfaces - Panels & Boards for - Watercolour Boards by Daler-Rowney 100% cotton rag on an extra thick board that eliminates the need for stretching.