Introduction to Canvas
Most oil and acrylic paintings are created on canvas. Canvas replaced wood panels during the Renaissance as it allowed for larger paintings that were portable. Canvas was lighter and could be rolled, as well as being a more stable surface with less warping and cracking than a wood panel.
The first artists' canvases were made from high quality Venetian hemp sailcloth. The word canvas derives from cannabis (hemp). Canvas made from linen was introduced soon after. Cotton is a more recent choice of fibre for painting.
Whether you are stretching your own canvas or buying ready-prepared canvases or boards, there are many types of canvas fabrics to choose from. The features you require of your surface will determine which you choose. The weight of the fabric, the material it is made from, and the surface preparation, in different combinations, will each give a different experience and affect the final appearance of your painting.
What Is a Stretched Canvas?
Canvases are tightly stretched onto a frame, which creates a spring in the fabric when pressure is applied, i.e. when paint is applied with a paintbrush. Many believe that the more tightly stretched a canvas, the more enjoyable it is to paint on, as the tension in the surface has an element of vibrancy. The tightness of a canvas must be the same across the whole frame so that the grain of the fabric is square to the edges, with no skewing.
Ready-made or pre-stretched canvases commonly have a universally primed canvas stretched onto a wooden frame with bevelled edges. This is so that the edge of the frame does not leave an imprint when the canvas is painted on. A canvas that is universally primed means that the canvas is coated with a white acrylic primer, which coats the fabric so it is ready for both oil and acrylic painting. Most ready-made canvases are triple primed (coated three times), and some have even more layers of primer. Lots of thin layers of primer are preferable to one thick layer. This creates a more stable surface which is less likely to crack over time. Thin coats will also be much more likely to be even across the whole surface.
Canvas is fixed to the frame with either tacks on the sides, staples on the back, or both.
Ready-made canvases are available in a range of depths. If this is important to you, it is vital to check the dimensions. Standard depth canvases are thought to look more traditional and are easier to frame, whereas deeper canvases tend to be associated with more modern art techniques, although the trends are always changing. This choice is one of pure aesthetics. A standard depth canvas does not perform better or worse than a deep edge or chunky canvas. One thing to consider is that larger canvases with thin bars may need to be reinforced by the use of a crossbar.
Choosing the Right Canvas for Your Painting
At Jackson’s we stock a wide variety of canvas that should cover most artists’ needs. You can get a huge range of sizes and surface characteristics in ready-to-paint stretched canvases. Just unwrap them and paint! Or you can add a final coating of ground to customise your surface. There are thin canvas panels and Ultralite boards which are great for plein air painting because they are lightweight and will fit in most pochade boxes. If you wish to stretch your own canvas, Jackson’s has dozens of types of canvas by the metre or by the 10-metre roll.
Many artists try different canvases, primers, and grounds until they find the surface that works best for how they paint. The surface qualities can profoundly affect some artists’ painting, even more so for techniques like staining in oils or acrylics. You can compare some of the canvases that Jackson’s stock by ordering samples. These include Belle Arti Canvas Samples, plus the Belle Arti or Claessens sample book.
Here are some things to consider when choosing which canvas to paint on:
Material
There are two main fibre types used to make canvas: cotton and linen (flax). Some speciality fibres such as hemp and jute are also used for canvas. Although it is a different fibre, jute is sometimes called an extra-rough linen because it is very similar.
Cotton
Cotton is economical but not as strong as linen. Cotton is easy to stretch and stays tight on the stretcher bars. Linen is made from flax and is stronger because it has longer fibres. This means that it is less likely to tear at the staple line or at the sharp outside corner of the stretcher bar. It also means that you can use finer and thinner linen for the same strength as heavier cotton.
The stiffness of linen means it is harder to pull when stretching. You need to take care to keep even tension across the canvas or it can ripple along the edges later. Linen is known to be much more difficult to stretch than cotton, so some artists choose to buy ready-prepared linen canvas. Unprimed cotton is usually a cream colour and unprimed linen is usually brown because it is unbleached. Cotton Duck Canvas has more tightly woven threads than plain cotton canvas. The term ‘duck’ comes from the Dutch word for cloth, doek.
We stock two types of cotton by the metre. Cotton Duck is the most common canvas in the world. It has many uses outside of art (canvas bags and so on), it usually has a noticeable weave and is quite thick. We stock it in three weights. Because of its low price, it is our most popular canvas sold by the metre (and the roll) and for our bespoke canvases – the 12oz primed, to be exact.
Our Italian Poly-cotton is an artists' canvas designed with a tighter weave, a finer thread, and an overall smoother surface. Even the ‘medium’ texture Italian cotton is finer than the cotton duck we stock. There is also a super fine texture called No Grain. The addition of polyester means the fabric will not ‘relax’ as much as all cotton and become loose over time.
Linen
Linen is more expensive than cotton. This is partly because cotton canvas is much more common and there are many non-art uses for it. There is professional quality cotton canvas, which is more expensive because it has a much smaller demand. Linen is also more costly than cotton because it takes more steps to process the flax fibres. Its inelasticity also makes it harder to weave into fabric.
We stock linen by the metre from three manufacturers. The French linen canvas from Artfix is made of smoother, more tightly spun yarn than the Italian linen from Belle Arti. It also has a more regular, tighter weave and is really strong. The Belgian linen from Claessens is between the two.
The famous Artfix company uses the highest grade of flax and has amazing quality control, so it is a superb linen. If you paint, scrape, repaint, scratch back, repaint, impasto, scumble glaze, and generally are hard on your surfaces, then the tough French linen is a great choice. Because it is so tight it can be a chore to stretch it. It is our highest priced canvas.
Claessens is located in the middle of the Flax District in Belgium. Their linen is made using small scale production and longstanding traditional sizing and priming methods. They apply the primers by hand with a palette knife. The Italian linen from Belle Arti is made with a bit coarser thread and more irregular weave but is of very good quality. It is also easier to stretch than the French linen. We also stock jute for a coarse 3D texture and at a low price for its thickness.
In addition to its great strength and the fantastic surface it gives for painting, linen has cachet among art collectors and so artists will usually mention in their materials list if it was painted on linen. There is also something romantic about painting in oils made with linseed oil on a linen canvas, as both are made from the flax plant.
Weave
In addition to choosing the fibre type, you also need to consider the weight and the texture of the weave. Similarly to paper, canvas is measured in grams per square metre (gsm) or ounces per square yard (oz).
If the linen has a heavy weight then one or both of the following is true: it is a thick, tough yarn and/or it is tightly woven. Lightweight linens have an open weave and generally a fine yarn. They are easier to stretch and are more responsive to tightening procedures. The lighter weight canvases are usually used by artists who draw and/or have a light touch in their work, but even some impasto painters can use them as their paint skims over the air holes.
A fine canvas has minimal texture and can be almost smooth, while a rough canvas has a very pronounced weave. The choice of no grain, extra-fine, fine, medium, rough and extra-rough texture in a canvas affects the feel of painting and the final appearance. Do you want to see the grid-like weave, to have your brush skip over the bumps to leave bits of white to sparkle, or to build up layers of paint on the weave high points; or do you want a surface where the canvas is not a noticeable feature? Do you want a texture that thick paint can grab onto, or a smooth, slick surface for thin paint to glide over? A smooth texture is often important to portrait painters, as a coarser texture can distort the appearance of skin. This is why extra-fine linen canvas is sometimes called Portrait Linen. The ‘No Grain’ texture is almost as smooth as paper and great for portraits.
The terms ‘super fine’, ‘extra fine’, ‘fine’, ‘medium’, and ‘rough’ refer to the texture of the weave, not the weight. Texture is not necessarily a guide to weight. You can have a lightweight canvas with a rough or medium texture, or a heavier weight canvas with an extra-fine texture. The 574 Italian universal primed linen is both lightweight and so fine that it feels like a sheet of paper. Because it is linen, it is strong enough to stretch tightly. Some artists particularly love the 574 canvas because it can take watercolour and ink. The 568 universal primed Italian linen is strong and heavy enough for large scale work, and has enough give to be able to stretch nicely. It has a tight weave so can be used for both glazing and impasto work.
Weight
The heavier the weight, the more tension the canvas fabric can take without tearing. For very large stretched canvases, you might wish to choose a heavier canvas. Weight is how much fabric there is per area. It is determined by both the thickness of the thread used to weave and how tightly it is woven. A coarse/rough canvas can be loosely woven so it could be lighter weight than a fine canvas that is tightly woven. But usually, a thick thread makes a heavy canvas and a thin thread makes a light canvas.
Unprimed canvas can be considered lightweight at about 5oz (140g); medium weight at about 8oz (230g); heavy weight at about 10oz (280g) or more. When the canvas is primed, the weight listed includes primer. It can be hard to compare the weight of the actual canvas as some have a much thicker layer of primer than others. When we have the information, we list the canvas weight on the Jackson’s website both before and after priming.
Brand
Jackson’s stocks four brands of artist canvas available by the metre. These are Artfix (French linen), Claessens (Belgian linen), Belle Arti (Italian linen and cotton), and Jackson’s (Indian cotton). These high quality canvases are also used for our Bespoke stretched canvases, our professional ready-made stretched canvases, and our Handmade Linen Boards.
Rolls of Canvas
Canvas comes in rolls which are 210cm or 183cm wide. A full roll is 10m long. You can purchase the full roll or metres cut off the roll (these must be whole metres, not partial). We also offer half-width rolls. These are easier to ship and store in the studio if you are not making very large canvases. Folding primed canvas can crack the primer so it must always be sent and stored on a roll, even if it is just one metre cut off the roll. But unprimed canvas can be removed from the roll and folded which can save on shipping charges as a roll is quite long and attracts over-sized shipping charges.
When measuring to purchase canvas to stretch your own, be sure to account for the amount required to go up the sides or around to the back of your bars, plus the additional amount you will need to grab and pull with your pliers. Also, account for the different widths of some of the rolls of canvas.
Stretched Across Bars or Mounted on a Panel
Depending on painting style, some artists like the bounce of a canvas stretched across bars. Others prefer the lack of movement of canvas glued to a panel (also called a board). The rigid support can be made of solid wood, plywood, MDF, heavy card, thin stiff plasticised card, or Gatorboard (plastic impregnated foam board). The canvas can be cut off shear with the edge of the support, or it can be wrapped around the back and glued down.
Shape
As well as traditional landscape and square canvases, some artists prefer working on more unusual shapes. For example, a 'tondo' refers to a circular work of art, a term that dates back to the Renaissance, with roots in Greek antiquity. A circular or oval relief sculpture is also called a roundel. Fredrix offers a range of round and oval stretched canvases made with double-primed, medium texture cotton duck canvas. These canvases are suitable for oil and acrylic paints, as well as for mixed media painting.
Boards and Panels
Canvas panels are sheets of compressed card onto which universal primed cotton canvas has been glued. These are ideal for quick sketches, but can also be easily framed as finished paintings. Canvas boards by Belle Arti are made of acrylic primed cotton duck glued onto MDF with shear edges. These are slightly sturdier and heavier, and a great rigid support with the grain of a canvas. Daler Board by Daler Rowney is an affordable and rigid oil primed support ideal for painting en plein air.
Canvas Pads
Our wide range of canvas pads are perfect for experimenting in the studio or on the go. Canvas pads are usually made of sheets of universally acrylic primed canvas, glue bound on one edge so that you can paint on sheets while they are still in the pad. You can also fix them onto a board with glue or masking tape for more stability. Oil and acrylic blocks by Clairefontaine, Hahnemühle, and Jackson's, as well as pads from the Daler Rowney System 3 and Georgian ranges, are made of specially treated papers for use with either oil or acrylic paint. All varieties have a fine art linen effect texture. Oil/acrylic blocks are glued on all four sides and sheets need to be sliced with a palette knife after the work is complete and dry. This prevents any warping in the sheet during the drying process. Pads are only glue bound on one side, and in all cases, can be presented to gallery standard by reinforcing onto a backing board and framing.
Sizing and Priming the Canvas with a Ground
The final thing to consider is the primer on your canvas. Creating a stable structure before you begin adding paint will help to ensure that the painting will remain in the best condition for the longest time. You can choose from a wide range of primed surfaces, or go with unprimed and treat the surface yourself.
Canvas comes either uncoated or with a primer coating. Jackson’s stock unprimed, universal primed, oil primed, gesso primed, and glue sized canvas. These come by the roll and on many of our panels and professional quality stretched canvases. Not all types of coating are available on all types of canvas or in all formats. The priming can be sprayed on in one to seven coats. Less expensive student-grade canvases tend to receive one coat, while most artist-grade canvases get two to four coats. Claessens apply their primer by hand with a palette knife to make sure it is scraped into the weave for the best adhesion and protection of the canvas. For the oil-primed linen, they follow up with a final coat of primer applied with a roller.
You can add your own additional coating on top of a ready-made universal primed canvas. You may wish to:
- Make the surface more white.
- Colour the surface but keep a gesso texture by adding a tinted ground, a mid-tone coloured ground, or a black ground.
- Make the surface absorbent enough for watercolour paint by applying a few coats of watercolour ground.
- Add an oil ground for the unique texture that it provides.
Sizing
You can paint on unprimed canvas directly with acrylics but if you are painting in oils and you want the painting to last, you will need to seal the surface. Oil paint dries by oxidation, slowly absorbing oxygen from the air. If canvas or paper is in contact with the oil in oil paint or oil primer it slowly corrodes the canvas fibre. To prevent this canvas needs to be sealed from oil penetration. This sealing process is called ‘sizing’ and the sealant is called ‘size’ – so ‘to size’ your canvas means to seal it. Size is either hide glue (rabbit skin glue or 'RSG') or acrylic polymer.
The secondary purpose of size is to stiffen the fabric so it has less bounce. RSG comes as pellets that are soaked to soften them and then gently warmed to use as a size or part of the recipe of genuine gesso. Warming RSG is not a smelly process. The reputation for smelliness comes from leftover liquid glue rotting in a corner of the studio days later. It doesn’t rot after it is dried on the canvas. If you do decide to use it, be aware that if you do either of these two things the glue will be less effective: over-heat it, or use it after it has rotted from sitting out as a liquid for days.
Recent studies have shown that RSG is problematic as a size. This is because it continuously absorbs moisture from the air, causing it to swell and then shrink when the air is dry. Over time, this constant change in the surface under the brittle layer of oil paint causes the oil paint to crack. RSG is now understood to be the main factor of cracking in old oil paintings. For a more lasting solution, many artists now use a fluid acrylic polymer or a PVA size to seal the canvas. GAC 400 is also used to stiffen the canvas.
A wide range of traditional and modern canvas sizes (sealants) can be found at Jackson’s.
Glue Sized Canvas
Purchasing canvas that is already glue-sized saves a step when you are stretching canvas. It also makes the linen easier to stretch evenly, as the added stiffness helps it keep the weave shape.
Priming
The type of ground affects many things about the painting. The amount of tooth affects how well the paint adheres and how much brush drag you feel as you paint. The amount of absorbency also affects the glossiness and brightness of the oil colour. As the oil is absorbed by the ground, and if the pigment is also sucked in, the colour will be diminished. An oil ground is often less absorbent and quite smooth for a silky painting experience where the colours sit proud and vibrant.
After you have sized the canvas you can apply one or more coats of ground. This is the surface you will apply paint to that gives the right amount of tooth. This is also called providing a ‘key’ for the paint to stick to. Priming your own canvas will allow you to work the first coat into the weave, to create a good barrier against oil paint penetration. Then, make the additional coats as smooth or as textured as you wish. Unless you sand the dried primer for a super smooth surface, there will probably be some brushmark texture.
Acrylic Primer
Acrylic primer usually acts as both size and primer. If you are using an acrylic primer to provide a barrier to oil paint, you can check if you need another coat by holding the canvas up to the light. If pin holes of light show through then you need more primer to seal it. When a canvas says it has Universal Primer, that means it is an acrylic primer that can be used with acrylic or oil paint. If it is labelled as acrylic ‘gesso’, this can mean it is more absorbent than acrylic ‘primer’, though this varies a lot by manufacturer.
To apply it, you usually thin it with water for the first coat and scrub it into the weave or scrape it on with a palette knife. Then get a bit thicker for each following coat. Applying primer too thickly may result in cracking when it dries as it will shrink a lot. So building up the surface with many light coats is better than one heavy one. A light coat is often dry enough in 30 minutes to apply the next one, so a batch can easily be done in one day. For the smoothest surface, many artists sand between coats.
Oil Primer
An oil-primed canvas can only accept oil paints. Although oil paint can be applied to an acrylic gesso primer, acrylic paint will not permanently adhere to an oil-primed canvas and will eventually peel off. Oil primer contains oil paint, and so you must apply a sizing of some sort first as a barrier. It usually takes a few weeks for the surface to cure. Then, the surface is ready to paint on.
Genuine Gesso
Genuine gesso is a very absorbent surface. This is what is needed for painting with egg tempera or encaustic. It is made in the studio and applied warm as it contains RSG. It will crack on flexible surfaces and should only be used on rigid surfaces, such as wood panels. We have a ‘gesso hand-primed’ canvas available in Italian linen. It has quite a delicate dry surface that is very absorbent yet it doesn’t easily crack (though it could if handled badly).
Surface Texture
Some painters like the look of the texture of the weave, so they do not add many coats of primer. They use just enough to seal the canvas and give it a white ground. Renaissance masters preferred a super smooth surface created by applying many coats of primer, sanding between each, until the weave was completely obscured.
Clear Primer
Some artists require a clear primer because they wish to use the colour and texture of the canvas as part of the painting. If you like the colour of the canvas and don’t want a white ground, you can prime the canvas with a fluid acrylic medium or a ‘clear acrylic gesso’. This will soak into the fibres and fill the weave holes. It usually takes a few coats.
For more information on Grounds, visit our Guide to Grounds.
You can also read our blog article 'Size, Primer, Gesso, and Ground Explained.'
How Do I Stretch a Canvas?
If you require a particular size or a type of canvas that is not available as a ready-made you may wish to make a custom canvas. Since the bars and canvas are typically more heavyweight, the quality will often be superior to that of most ready-made canvases.
For a visual guide to stretching a canvas, watch our video or visit the article 'How to Stretch Canvas: A Visual Guide.'
Summary of method and time it takes for each step:
1. Knock together stretcher bars with a mallet. Up to 5 minutes for a small canvas, up to 20 minutes for a very large one with two cross bars to fit in (some time is saved if you have a helper for the large ones and you might need a stepstool).
2. Do the calculation, measure, mark, and cut canvas piece with large shears. Less than 5 minutes per canvas, even faster when you have lots the same size.
3. Lay stretcher bar frame on a canvas piece and square it up. Less than 5 minutes for a small canvas, up to 5 minutes for large canvases.
4. Stretch canvas, including neatly folded corners. Up to 10 minutes for a small canvas, up to 30 minutes for a large one.
Total time: less than 30 minutes for a small canvas and up to an hour for a large one.
Part of the difference is that a small canvas can be made on a table and you can stay in place and turn the canvas. A very large canvas needs to be made on the floor or a large work table, and you have to move around it.
What Tools Do I Need for Stretching Canvas?
The tools needed to stretch a canvas are simple and easy to acquire:
- A rubber or plastic mallet or a hammer with a piece of wood. This is used to assemble the stretcher bar frame without denting it.
- A measuring tape or metre stick. To measure corner to corner to ensure the stretcher frame is square.
- A pencil and straight edge (for marking your canvas to cut).
- A strong pair of scissors or a utility knife and straight edge. This is to cut your piece of canvas off the roll and to size.
- A pair of canvas pliers. Used to pull the canvas tight.
- A heavy-duty staple gun and staples. Manual or electric. Used to attach the canvas to the back of the stretcher frame. Or canvas tacks and hammer to attach to the sides of the stretcher frame.
- A staple lifter. Useful if you need to remove staples that aren’t quite right to adjust the tension.
- A tack hammer. Used for tapping in staples that stick up and for tapping in wedges.
Canvas Pliers
Canvas pliers are vital for achieving a good amount of tension when stretching your canvas. Place your canvas frame in the middle of your piece of canvas and make sure you have enough canvas to wrap around to the back of the frame. Use the pliers to grab enough of the material between the teeth of the pliers. Then use the ridge on the underside of the pliers to gain leverage over the edge of the frame. Now, stretch the canvas around to the back of the frame.
Always stretch the canvas from the middle of the bars moving outwards. Also, always insert staples opposite the ones you have just put in. A staple gun is the easiest to use. Small tacks are the traditional method. Finished artworks that have been made on unstretched canvas can be fixed to a frame once dry, and do not need as much tension when being stapled. Just make sure they are fixed square to the frame and that you do not lose too much of the image when wrapping the work around to the back.
Staples and Tacks
Tacks can be gently hammered into the edge of the canvas frame before a staple secures the canvas to the back. This helps to achieve a good amount of tension and adds a traditional look to the finished support. The pressure that a staple gun provides makes it easy to punch in staples to secure the canvas to the back of the canvas frame. Remember to leave enough room at the corners to fold your canvas neatly before punching in the final staples.
Further Reading
How to Stretch Canvas: A Visual Guide
Choosing the Right Canvas for Your Painting
How to Use Canvas Wedges for Canvas Stretching
Making a Canvas Painting Panel
Comparing Watercolour Grounds on Canvas
Rabbit Skin Glue: Preparation, Uses and Alternatives
Glossary
A
Acrylic Gesso
A primer which dries with a coarser texture (or ‘tooth’) than regular acrylic primer. Acrylic gesso can be sanded down if desired. It is made from a mixture of chalk and pigment (usually Titanium White), bound in a 100% acrylic emulsion binder. It can be used as a ground for both acrylic and oil painting.
Acrylic Painting Block
A stack of paper that has been specially prepared for acrylic painting. Usually sprayed with acrylic primer and glue bound on all four sides. A gap in the glue will be found on the corner or part of a side of the block, so that when the painting is finished and dry the top sheet can be separated from the block. This is done by running a clean palette knife around the underside of the sheet. A block is a lightweight support for acrylic painting that will not buckle during the painting process as the glue binding will keep the sheets taut and flat.
C
Canvas
A woven material used for centuries for painting. Usually made of cotton or linen. Can be stretched over stretcher bars, glued onto a board or panel, or used unstretched. Although acrylic can be painted on raw canvas, most artists prime the cloth with a ground. A ground provides control over the absorbency, texture, and colour of the surface.
Canvas Board
Canvas glued on to a hard board (thin MDF or compressed board). A rigid surface for oil and acrylic painting. Canvas board usually has shear edges (i.e. the canvas does not wrap around to the back, unlike a canvas panel).
Canvas Pad
A pad of unstretched, primed canvas sheets glued at one side ready for oil painting. Also available in blocks that are glued on four sides.
Canvas Paper
Pads or sheets of paper that are made to have the appearance and feel of primed canvas. Used instead of canvas for economy and convenience.
Canvas Panel
A piece of board or wooden panel on which a piece of primed canvas has been glued to the front and wrapped around to the back.
Canvas Pliers
A tool which helps to stretch canvas tightly around a frame. Helps to make a taut surface on which to paint. Canvas is usually fixed to the frame using staples on the reverse of the frame, or tacks on the side of the frame.
Canvas Sheets
Sheets of rectangular or square pieces of primed canvas that can be glued to a board to make a panel, or painted on as they are.
Cotton Duck
A heavy plain woven fabric that is popular for artists' canvas. It is relatively low cost in comparison to linen. Cotton duck is most commonly available in 10oz or 12oz weights.
Crackle Paste
When applied to a rigid support with a thickness of at least 3-4 mm, crackle paste will form cracks as it dries, which gives work an aged appearance or can be used for special effects showing through colours from underneath. It can be applied on its own or mixed with colour. The thicker the application the deeper the cracks. When dry, oil or acrylic paint can also be applied over the top of the paste.
Curing
The second stage of drying of acrylic paint. Acrylic paints dry when all the water found in the paint has evaporated, leaving the dried paint (pigment mixed into acrylic polymer). As the moisture leaves the paint film, the remaining tiny polymer spheres move closer together. This causes the paint film to contract slightly. This pressure causes a capillary force which pushes the last of the moisture out of the paint film, until the polymer spheres start to deform and make bonds between one another. This results in the paint coalescing and forming a continuous paint film. Curing times will vary across brands. It is worth checking the manufacturer’s information if this is of particular concern.
D
Dry Brush Technique
The application of paint with very little water content in it using a dry brush. Applying paint in this way is also known as scumbling. The results can have a powdery appearance.
E
Emulsion
An emulsion is any mixture that doesn’t separate. In art, this can be a cold wax medium or an acrylic polymer (acrylic paint).
F
Flat Colour
A uniform application of paint, i.e. without any texture or undulation in tone.
Flow Release / Flow Medium
Reduces visible brushmarks and increases the fluidity of acrylic paint. The go-to medium if you want to create stains and washes on a porous or non-porous surface. Flow release breaks the surface tension of water, so allows fluid acrylic to spread rather than bead up. Many brands are very concentrated and you just need a drop, so they recommend making a bottle of water with diluted flow release to use. Some brands are already diluted so you use a full amount – so be sure to read the instructions on the label.
G
Gesso
Pronounced with a soft g like gypsy or George. From the Italian for gypsum. This thick white liquid is primarily used as a ground for painting. It can also be used to build up areas for carving on frames and is used underneath gilding. It can be coloured. Gesso for gilding is often coloured red. You can buy ready-made black 'acrylic gesso'.
Gesso is made with calcium carbonate (also called whiting, chalk, or gypsum) in a binder. It is painted on the surface to create a ground on which to paint. Sometimes white pigment (usually Titanium, sometimes Zinc) is added to make the gesso very white.
Genuine gesso (also called true gesso) uses animal skin glue (hide glue or rabbit skin glue also called 'size') as the binder. The artist often makes the gesso him/herself, using a double boiler to melt the glue powder and adding the whiting. Rabbit skin glue is now also available ready made and just needs to be warmed.
One recipe for traditional gesso: 3 parts size, 1 part chalk (whiting), 1 part pigment powder. It is a rather lengthy, messy, smelly process of soaking, heating in a double boiler and mixing.
'Acrylic gesso' is more correctly called 'acrylic primer'. It should not really be called gesso. It uses an acrylic polymer as the binder for the chalky powder. It is made up of upwards of 14 ingredients. You can also buy ready-made black acrylic primer.
Genuine gesso is less flexible than 'acrylic gesso'. It is usually painted on a non-flexible surface such as a wood panel, rather than on stretched canvas, so that it will not crack. For paints that need an especially porous surface, like egg tempera, genuine gesso is often preferred to the acrylic gesso/primer.
Acrylic primer can vary a lot in quality. Poor quality products can provide a less absorbent ground than is often preferred. Good quality acrylic primer is great for oil and acrylic painting. It does both steps of the surface preparation in one: it sizes (seals) the surface, and gives a ground for painting. They can also vary in absorbency. Some products called acrylic 'gesso' rather than acrylic 'primer' can be more absorbent and chalky. These are particularly suited to applications which require an absorbent surface.
Acrylic primer differs in thickness, opacity, and grittiness of surface texture, depending on the manufacturer. It is usually too thick to use straight out of the bucket and should be diluted with water until it is the consistency of heavy cream. Most primers have instructions that advise you apply three thin coats rather than one thick coat. A very thick coat may crack as it dries. The first coat is often scrubbed into the weave of the raw canvas in circular motions to be sure that it is well sealed. The first coat will soak into the canvas or panel and act as its own sizing (sealer). Then subsequent coats are applied in alternating directions across the canvas. To get a very smooth surface, you may wish to sand with sandpaper between coats. Some acrylic gessoes are designed to have a harder surface specifically so they may be sanded smooth. However, as they are less flexible, they may crack on a movable surface such as stretched canvas. They should only be used on rigid surfaces.
For oil painting, it is especially important that the oil never reaches the substrate. This will cause it to rot. Traditionally, oil painters seal the surface with rabbit skin glue and then prime the surface with gesso (glue with chalk). Using these two layers assures that none of the oil will seep through. Some artists who use ready-made stretched canvases will apply an additional layer of acrylic primer to the surface to ensure that it is well sealed.
For painting on paper, you may wish to prime both sides of the paper (one after the other dries) as the paper will curl when it is wetted by the primer. Painting the other side then uncurls it. For oil paint on paper, you may want at least three coats.
Priming your painting surface is part of properly creating a painting. The underlying structure is very important to the longevity of the painting. It also affects the appearance. Primer creates a surface that is sealed just enough to prevent the paint seeping through to the substrate, but is absorbent enough to hold onto the paint. If you were to paint on an unusual surface like a rubber toy, the paint might not adhere properly. But if you prime the surface with acrylic gesso/primer first, then your paint will go on properly and stay on. The primer is stickier than paint and will glue the chalk to your substrate and create a better surface to paint on.
While the gesso/primer is wet it may leach colour up from the substrate and cause discolouration to the whiteness of the gesso. The glues in plywood, the resins in wood panels and in stretcher bars may be water-extractable. Sealing the wood or canvas first with a sealant medium such as Golden Acrylic GAC 100 will prevent Support Induced Discolouration (SID). Sealing (sizing) with rabbit skin glue does the same thing if you are using genuine gesso. Then prime as normal.
Some artists prefer that the substrate shows through underneath the paint and so they use a clear primer. This is usually an acrylic matt medium. This is a thick white liquid that dries clear so you can see the canvas. The texture is very different to gesso since it does not have the chalk powder in it. The surface is smooth and not as absorbent.
Be warned that priming can be a messy business. Gesso/acrylic primer dries quickly on brushes and can stain clothes. Be sure to use drop cloths and wash everything as soon as possible.
Many artists use the word gesso as a verb meaning 'to prime', as in 'I will be spending the day gessoing canvases in the studio'.
Some artists mix gesso in with their paint as a painting material.
Ground
A term often used to describe a prepared surface ready for oil painting. The word ‘ground’ could refer to anything from a primed piece of canvas to an aluminium sheet. A painting ground is the surface onto which you paint. It can be anything. It is usually on top of a sealant/sizing layer. To be structurally sound it should be compatible with both the underlying support and the paint that is going onto it. Just a reminder that an artist concerned with the permanence of their paintings should be as concerned with the proper preparation of the foundation layers of the painting that are not visible (the support, the size and the ground) as the layers they do see (the paint, mediums and varnish).
The ground gives a suitable surface texture and an opaque colour. Artists can cover the canvas or panel colour with white or a tinted ground, or a dark colour.
Acrylic primer (less correctly called acrylic gesso) is an example of a ground that is also a size. It does both jobs: sealing the substrate and providing a good surface on which to paint. Genuine gesso is a painting ground for oil paint and egg tempera, but any paint can be used on it. An oil ground is oil paint painted on top of a sizing over the entire surface to prepare the surface for painting with oil colours. Using an oil primer means you cannot paint on that ground with acrylics as the ground will repel the paint.
Painting with soft pastels requires a ground with a tooth to pick up and hold the pigment. This toothy pastel ground can be painted onto paper, canvas, and panels. Surfaces can be purchased with the ground already applied to them.
Absorbent Ground can be used to create an absorbent paper-like surface on canvas or panels for painting with watercolours. It is painted onto sized or primed canvas or panels. It acts as the painting surface, not the sizing layer, so the substrate must be sealed first.
I
Imprimatura
In Italian, ‘imprimatura’ means ‘the first layer’. In painting it refers to a thin transparent layer of colour that is laid onto a ground evenly to colour it. The layer is thinned with solvent or with a fast drying medium. It is then left to dry before the actual painting of the picture begins. Many artists will leave patches of the imprimatura layer showing through in their work. It is an alternative to a tinted or coloured ground, where the primer is mixed with a colour prior to application to a support.
L
Lightfastness/Permanence
Refers to the stability of a pigment when exposed to prolonged periods of ultraviolet radiation (UV). UV is found in natural sunlight. Lightfastness is measured using the Blue Wool Scale in the UK and ASTM in America. Permanence takes into consideration the effects of other elements on the stability and appearance of pigments, such as humidity, light, heat, water, acidity, alkali levels, etc. The permanence of a paint will be shown on the label using a rating system determined by the manufacturer. More information can be found in the manufacturer’s colour chart or on their website.
Linen
A natural fabric made from long threads woven together. Stronger and more elastic than Cotton Duck. It is usually darker than cotton duck and can be stretched on a frame, glued onto a board or panel, or painted on unstretched. Linen needs to be sized with rabbit skin glue or an acrylic substitute prior to painting with oils. Linen is available in a range of weights and weaves, from fine to coarse. The heavier the weight, the tougher the fabric will be. Which you choose will impact the overall look of your painting.
M
Matt
Also spelt ‘matte’. A complete lack of shine on the surface. The opposite of gloss.
Medium
An additive that is mixed with paint to extend the colour or alter some of its properties. This can include consistency, texture, transparency, and drying time of the paint.
Monochrome
The use of only one colour in a painting. This colour is likely to appear in a range of differing tonal values.
Moulding Paste
Moulding (or molding) paste is a white opaque acrylic paste that can be used to build layers and create texture on a painting surface. It can be tinted with acrylic colour or applied on its own, left to dry, and then painted afterwards. It dries hard yet flexible.
O
Open Acrylic
Open acrylics are slow drying acrylic paints. They help artists achieve painting techniques that were only previously possible with oil paints.
Open Time
The length of time in which it is possible for a brush to move applied paint around on a surface before it dries. Also used for the time a gilding size (adhesive) stays sticky for metal leaf application.
P
Palette Knife
Palette Knives are also known as painting knives and are used by painters to mix colour and apply paint to a support. They are usually made from plastic or metal. They are easy to wipe clean with a rag, which means it is easy to keep colour mixes clean. As a painting tool, palette knives are ideal for impasto and for applying colour in a flat and uniform layer.
Panel
A rigid painting surface for acrylic, oil, encaustic, pastel, or watercolour. Made from solid wood, plywood, MDF, compressed card, or aluminium. They are often braced to prevent warping both during the priming and painting period and over time. It may also be wood with canvas or paper adhered to the front. Excellent for encaustic or oil painting where a rigid surface helps prevent cracking of the paint surface over time.
Paper
Watercolour Papers
Watercolour paper has a ‘hard size’ on top of the paper. This allows the water to penetrate and the pigment to remain on the surface. This gives the painting its brilliance and also allows for corrections.
Watercolour paper comes in different textures. ‘Hot Press’ (HP) is the smoothest. It is also a bit less absorbent as it has been compressed to a harder surface. ‘Not’ (also called Cold Pressed) has a medium textured surface and is the most popular finish. It is especially good for beginners. ‘Rough’ is highly textured paper and is the most absorbent. Botanical artists often prefer hot pressed paper as the smoothness allows them to be very precise.
The weights of the papers range from 90 lb to 400 lb. The heavier the weight of the watercolour paper, the less the paper will buckle when wet. For lighter weight papers (140lb and below) the paper is usually stretched. This involves the paper being wetted and laid out on a board and taped down with gum-strip tape. You can use a specially designed paper stretcher device like the Keba Artmate.
Watercolour papers can vary in whiteness. This ranges from bright white to a creamy off-white. They are also available in tinted colours.
Watercolour papers come in sheets, pads, rolls, and blocks. Blocks are pads of pre-stretched paper that are glued on all four sides except for a small space on one side. This allows for painting without stretching and when the painting is dry you can remove the top painted sheet by running a butter knife around the edge from the gap in the side.
Drawing Papers
Cartridge paper is a high quality type of heavy paper used for illustration and drawing. It comes in a variety of smooth textures. It is available in loose sheets, pads (glued or spiral), hardbound and softbound sketchbooks and rolls.
Bristol paper is a strong and durable, all-purpose drawing paper. It has a very hard surface that is heavily sized, polished, and compressed. It is also used for airbrushing.
Other papers that are suitable for drawing include the popular Stonehenge paper.
Pastel Papers
Pastel paper is used for soft and hard pastels and charcoal. It is usually coloured paper. The chosen colour is very important as it will be a major component of the finished work. It comes in a few different textures, all with some amount of tooth or weave that will catch hold of the pastel particles. Ingres is a laid paper with a mesh imprint from a screen. The random texture gets its surface from a cloth matt imprint, similar to Not texture watercolour paper. There are a few types with toothy textures, from ground cork or sand that are similar to sandpaper. A few come with the colour screen printed on and some are waterproof for working the pastels with water. Paper for oil pastels is hard and white and usually comes in a pad with glassine paper interleaving to protect it from smudging.
Oil and Acrylic Painting Papers
These medium to heavy weight papers are usually canvas textured and primed for painting with either oil or acrylic. Most of the papers prepared for acrylic paint are universally primed to accept both oil and acrylic. Paper must be sealed completely if painting with oil paints because the oil will separate out if the paper is absorbent. It will then form a halo of oil around the colours. It will also rot the paper over time. Although acrylic paint can be used on any paper, acrylic painting paper is usually designed to mimic canvas or it is very heavy weight. Oil and acrylic painting papers are useful for taking to classes or painting en plein air. They are an economical choice for making a study or sketch prior to a major work on canvas.
You can also buy sheets of real primed canvas (as opposed to the canvas-textured paper) in pads.
Fine Art Digital Papers
Inkjet papers are used to create high quality reproductions of your artwork or prints of your digitally designed original prints. They come in a wide variety of textures and weights. Inkjet papers are coated to accept inkjet inks. They can be sprayed with an inkjet fixative to prevent smudging if that is a problem. They are archival. Sheets of primed canvas designed to go through your inkjet printer are also available.
Paste (Acrylic)
A thick, white opaque medium. Can be tinted with acrylic colour or used on its own on a support to build up texture and impasto marks. There are many acrylic pastes available with a variety of different consistencies and textures.
Permanence
Permanence takes into account all factors that may influence the stability and appearance of pigments. This includes exposure to UV rays, humidity, heat, water, acidity, alkali levels, etc. The permanence of a paint will be shown on the label using a rating system determined by the manufacturer. It may also be explained in the manufacturer’s colour chart or on their website. Some manufacturers say permanence when they mean lightfastness (which only considers UV). It is worth double checking if this is of particular concern.
Pigment
Pigments don’t just give a paint its colour. They will also alter how the paint behaves as you work. Tinting strength, opacity, granulation, and other properties are all a result of the pigments used in a paint. Even when different brands produce even the most familiar colours, it’s best not to rely on titles alone.
Pigment numbers are grouped into nine categories. Each is prefixed with a code that will help you decode how your colours are made. These codes are PR, PO, PY, PG, PB, PV, PBr, PBk and PW. They refer to Red, Orange, Yellow, Green, Blue, Violet, Brown, Black and White, respectively.
Some pigments will crop up again and again across a colour chart. For example, PBr7 is the natural iron oxide used to produce raw and burnt umbers and siennas. Others will appear in variations. This is either denoted by a colon or a secondary figure, such as PW6:1 for Buff Titanium derived from PW6 Titanium White. They can also be listed in brackets after, as in PV23 (RS), a Red Shade of the Dioxazine Violet pigment. It can be useful to look at the paints you use most often and make a list of your preferred pigments. This is especially useful if you are looking to purchase colours from new brands.
While there are plenty of good reasons for a manufacturer to mix pigments, painters will often prefer to use colours with one pigment. Single pigment paints are more predictable in mixes and tints. A paint made from multiple pigments might create unexpected combinations on your palette. Still, mixes can be beneficial. They are commonly used in the production of hues. These are convenient replacements for dangerous or expensive pigments. They are often the only form in which defunct historical colours can be found.
Plein Air
To paint out of doors in front of the subject. Famous artists who painted en plein air include Pissarro and Renoir.
Primer
A surfacing material used to coat a support to get it ready for paint application. Acrylic primer is made from calcium carbonate suspended in an acrylic binder. It can be applied directly to a support without the need for a prior application of size. To create a very smooth surface, apply two to three coats and allow to dry fully, lightly sanding between applications. Gesso is a more absorbent variety of primer. Multiple coats of acrylic gesso will increase the absorbency of the surface. Light sanding between layers will increase its smoothness.
Acrylic primer varies a lot in quality. Poor quality products can provide a less absorbent ground than is often preferred. Good quality acrylic primer is a great product for both oil and acrylic painting. It does both steps of the surface preparation in one: it both sizes (seals) the surface, and gives a ground for painting.
Priming Brush
Usually a flat wide brush, made with synthetic or hog hair. For an even application, load the brush and apply whilst holding it at around 45 degrees to the support. Brush the primer on in all directions to make the coverage even. Allow each layer to dry fully before applying the next layer.
R
Rabbit Skin Glue
A strong glue made from animal parts. An ingredient in genuine gesso, used for sealing (sizing) panels and canvas before priming. Used as sizing for papers. It stiffens canvas in preparation for gesso primer in oil painting. Also called hide glue.
For preparing canvas and panels, the usual method is to soak the pellets or powder overnight. The next day, heat in a double boiler and brush onto the canvas while still warm. Do not overheat as the glue will be weak. Two coats are preferred to seal the canvas well, the first being scrubbed into the canvas to get well into the weave. Discard any leftovers as it does not reheat well. Then prime the surface as normal.
S
Sinking In (Oil Painting)
When paint is absorbed by the surface it has been applied to and the colours appear less saturated than when they were first applied. This can sometimes cause some areas of the painting to appear shinier and colour-filled than others. This can be due to inconsistencies in the absorbency of a surface, which affects the varying degrees of ‘sinking in’ on a surface.
Stretched / Unstretched Canvas
A piece of linen, hessian, or cotton duck that has been tightly wrapped around a frame made of wood or aluminium and fixed at the back. Sizing and priming the stretched canvas will increase the tension in the stretch. This creates a vibrant, drum-like surface to paint on. Stretched linen and cotton duck canvases can be bought ready-made. They are available unprimed or primed with acrylic or oil primer. Unstretched canvas can be purchased from and by the roll, ready to be stretched onto a frame at home or worked on unstretched.
Stretcher Bars
Stretcher bars will assemble to make a frame onto which canvas can be stretched over. They are available in pairs and made of wood or aluminium.
Support
A general term for a surface ready to be painted on. A support can be anything from a canvas to a wooden panel.
T
Tacks
Tacks are a similar shape to drawing pins. They are made of metal and are used to fix canvas to the sides of a stretcher bar. Staples are generally considered to be more successful at keeping canvas fixed to the stretcher. Tacks are often still used to add a traditional aesthetic to the overall look of the support.
Toning a Canvas
Painting on a white canvas can cause you to paint in colours lighter or brighter than you intend. This can mean you need to then adjust after you have more of the white covered. To avoid this, some artists apply a middle value on the whole canvas before they start. This toning of the canvas also prevents unwanted bits of white canvas from showing through your brushwork. You can also leave bits of the tone colour showing for added liveliness.
Tooth
Tooth in acrylic painting usually refers to how coarse a surface feels when dry. Often used to describe the surface quality of gesso, primer, and acrylic pastes and mediums.
Transparency / Opacity
The measure of how much light is able to pass through an applied paint and interact with the surface beneath. Transparent paints appear more luminous on a white support because they allow a larger amount of light to hit the surface they’re laying on, like a filter placed over a light bulb. Opaque paints block this reflection from occurring, and can be used to cover layers of colour underneath. Transparent paints are better for glazing techniques. These can still be achieved with opaque colours if diluted sufficiently or mixed with a suitable medium.
U
Undertone
The appearance of a paint when it is spread across a surface in a thin film.
Underpainting
The initial layer of a painting. Usually executed in only a few colours. Establishes areas of tone and ‘maps out’ the composition on the support.
W
Weave
The weave of a canvas can be completely smooth or very prominent, depending on how it was made. It will have an effect on how your painting looks. Artists who like to explore textures in their work might prefer a coarser weave. Artists who paint very fine detail may prefer a finer grain. The set of threads that are aligned lengthways in fabric is known as the warp, and the weft is the set of threads that weave in and out of the warp. In painting it is important that the warp and weft are similar, so that when the canvas is stretched, it will do so uniformly, without inconsistencies such as wrinkling. This is particularly worth noting if you are working with a linen that was not purchased from an art supplier.
Wedges
Wedges are supplied with ready-made canvases and stretcher bars. They provide a way of making your canvas even more tightly stretched. Simply insert the wedges into the corners of the frame of your stretched canvas and gently tap in with a hammer. The wedges will push the stretcher bars outwards and keep them in place. If the same amount of pressure is put on each wedge then the canvas will remain square. By pushing the bars outwards you will be tightening the tension of the canvas stretched on the other side of the frame.
Whiting
Calcium carbonate or calcium sulfate. Also called chalk, marble dust, calcite, and gypsum, depending on its source, use, purity, and particle size (which affects both the texture – gritty or silky smooth – and the absorbency). Talc is not included in this group and is too soft for use as a painting ground, unless it is used in a blend with one of the above minerals.
It is a white powder ground from fossilised shell deposits (limestone), marble, or made synthetically. It is made synthetically by precipitating fine particles of calcium carbonate. This makes the most uniform, smoothest variety that is used for the preparation of panels for egg tempera, for example.
Its use for artists is primarily as an ingredient in genuine gesso and acrylic primer.
It is also the opacifier that makes gouache an opaque form of watercolour paint. It is used in some soft and hard pastels. It is used as a filler for some paints. It is used to enhance the brightness of some paint colours, such as Viridian. It is the inert base onto which lake pigments are precipitated. Some forms are used in modelling paste in acrylics. Mixing with oil makes oil painting putty.
It is not strong enough to be used as a white pigment. It is added to paper pulp as a buffer, to counteract reactions with pollution that would cause acidity in paper. It is also used as a polishing powder and in ceramics as a flux.