Hints, Tips & Techniques for Water Colour - Surfaces

When using water based media, good results rely almost as much on the paper surface as on the quality of the colour used. The paper is an intrinsic part of the work.  This is also true for oil based paintings.  It is essential therefore that you have a range of  papers available which are of equal quality to the colour you are using.

Here is some useful criteria and terminology to help you choose the right type of paper when painting with water colour.

Criteria to consider when choosing your paper

A paper must provide a suitable surface for painting or printmaking in terms of absorbency, colour and long-term stability.  The correct degree of absorbency (sizing) allows the colour to sit on the surface and reflect the maximum amount of light.  White papers produce the brightest images, whilst coloured papers are used for opaque or juxtaposition techniques.  Long term stability comes essentially from the papers being acid-free [pH neutral].

Types of Water Colour Paper

Generally there are two qualities of paper available, both are mould made for greater stability. The first is made from cotton and the second from chemically processed wood fibre.

Rag / Cotton Water Colour Paper
100% rag indicates the paper is made from 100% cotton.  The reference to rag dates to the time that old rags were used in hand-made paper mills.  The cotton used in papermaking today is direct from the plant and is called cotton linters. 

Wood based water colour paper
A more economical mould made paper can be made by using chemically processed wood fibre or “woodpulp”. These papers are generally supplied in one surface only, Not/ Cold Pressed.

Paper Terminology

Mould-Made and Hand-Made
Mould-made refers to the cylinder mould on which the paper is formed.  The fibres are arranged at random, mimicking a hand-made sheet.  This arrangement gives dimensional stability and a unique texture to mould-made papers.  Dimensional stability reduces cockling of the sheet when water is applied.  Hand made paper has these advantages but is relatively expensive.  The deckle is the frame which forms the outer edge of the paper sheet.  Four deckle edges is an accepted term to indicate the sheet is handmade.

Surfaces
Water colour papers are available in three different surfaces, Rough, Not and Hot Pressed. 

• Rough
This paper has a rough surface as the name suggests.  The Rough sheet has been pressed between the 'felts' on the paper machine and the roughness of the felt (blanket) is embossed into the wet sheet.

Rough sheets give the greatest texture to water colour washes as the pigment settles into the hollows of the paper.  Rough paper is popular for expressionist techniques and bold styles.

• Not/Cold Pressed
The surface of a Not (Cold Pressed) paper has a moderate texture.  A Not sheet gets its name from 'not hot pressed'!  It is made by taking a rough sheet and pressing it again without the felts.  Not papers are generally considered the easiest to use. 

• Hot Pressed
The surface of Hot Pressed paper is made very smooth by passing the sheet through hot metal rollers.  It is popular with those painters who like detail, do not utilise granulation particularly and with illustrators and designers who require flat artwork for reproduction.

Weight
The weight is measured in two ways, either Imperial or Metric.  The Imperial weight is that of 500 sheets of Imperial sized [30” x 22”] paper.  A lightweight water colour paper would be 90lb.  The Metric weight is grammes per square metre [gsm].  A 90lb paper is equivalent to 190gsm.  Papers are generally referred to as heavy or light in weight.

A heavier paper is more resilient to tearing/general storage, being stronger simply because there is more interwoven fibre in a heavy sheet.  Heavier papers are preferred by many water colourists as they are able to take heavier washes without cockling.  Lightweight papers should be stretched if substantial amounts of water are to be used. 

Cockling is the wrinkling of the sheet when substantial amounts of water are used.  Heavier sheets used in printmaking should be soaked long enough to ensure suppleness, a 300lb sheet should be submerged for at least 20 minutes.

Sizing
Sizing is the reduction of absorbency in the sheet.  Without it colour could not be drawn across the sheet as it would blot immediately.  Most water colour papers are both ‘internally’ and ‘externally’ sized.  Internal sizing reduces the absorbency of the fibre itself by chemically bonding to it.  External sizing is a layer of gelatine on the surface of the paper, resulting in the water colour film laying on the surface, looking brighter and allowing it to be sponged off if desired by the painter.  Gelatine gives a harder surface which also allows scraping and rubbing without damaging the paper itself.  External sizing is also known as gelatine surface sizing.
Printmaking papers are ‘soft sized’.  A low level of size makes the paper more malleable, particularly for intaglio work and also more absorbent, pushing the ink into the fibre and assisting drying.

Acid free
Acid free means pH neutral. This is essential for the long term stability of the paper. Acid free paper is produced by using cotton linter or woodfree fibre. Acidic papers, for example newsprint or sugar papers discolour and embrittle in a very short time, leaving a weak paper prone to disintegration.

Buffering
Artists’ papers are buffered with an alkaline filler, eg. calcium carbonate.  A small amount is incorporated into the sheet at the pulp stage.  This buffering allows the sheet to counteract any atmospheric acidity over the long term.

The ‘Right’ Side
The right side of the paper is the side from which you can read the watermark. However, either side can be used, it is entirely a matter of choice.

Painting on the back of a finished painting will save using a new sheet but this practice cannot be widely recommended.  A painting which is felt to be unsuccessful today may appear entirely different in the future, you could end up with two good paintings on only one sheet of paper.  Paintings may also appear less bright if there is a dark painting on the back of the sheet and may not stay flat.

Colour of Paper
Water colour papers are traditionally white, this allows the maximum amount of light to be reflected back through the wash, giving that characteristic water colour 'sparkle'. Tinted papers are sometimes preferred and give a mellow tone to a painting.

on cream

on green

Deckle Edge
The deckle is the frame which forms the outer edge of the paper sheet. 'Four deckle edges' is an accepted term to indicate the sheet is mould made.

Water Colour Blocks
Water Colour blocks are pads where the sheets are glued around all four edges to keep the paper flat whilst painting.  A small section is left unglued to enable a palette knife to slip round and remove the finished work.  Blocks are excellent for outdoor painting.

Cotman water colour block 

Stretching Paper
Stretching paper maintains a flat sheet when using large quantities of water.  All weights of paper will benefit from stretching, as once stretched, you are free to use as much water as you wish. Stretching works by soaking the paper to expand the fibres and taping it flat to dry taut. More water will not then be able to cockle the paper.

The important tips are:

• Soak the paper completely - 90lb for 3 mins, 140lb for 8 mins, 300lb for 20 mins
• Drain the paper of excess water
• If using a manmade fibre board, seal it with dilute French polish first.
• Use brown gum strip (not masking tape) to tape edges along their complete length
• Keep the board flat to dry