As the final installment of my investigations into artist's canvas, this time I'm looking at canvas keys, gallery wrapped canvas vs traditional profile canvas and the idea of unstretched canvas.

Previous related posts cover all about painting substrates, all about the types of artists canvas and stretching your own canvas.

Canvas Keys

Some stretched canvasses come with little wooden wedges. What are these for? They are known as canvas keys. They should fit into slots in the inner corners of the canvas stretcher. They are a traditional method for tightening up a canvas that has begun to sag. Unfortunately, they are not a very good method for doing this. Any canvas that has developed a sag should be carefully taken off it's stretcher and re-stretched.

Using canvas keys to take the sag out of a painting risks damaging the painting. It is possible to accidentally hammer the back of the painting if the keys are missed, breaking the paint. Using keys puts a great deal of stress on the corners of a painting which can eventually tear the canvas. The keys will invariably change the shape of the stretcher and it will no longer be square and the painting may no longer fit into it's frame, if it had one.

Skip the dodgy canvas keys. Traditional, but not very smart. Take the canvas off the stretcher altogether and re-stretch it!

This video explains the same information in visual form:
http://www.youtube.com/watch?v=tSLhkuFO3G0

Bracing a Stretched Canvas

A canvas stretcher or strainer is under quite a bit of tension once a canvas has been secured onto it. They are usually made from timber and so are prone to warping under tension and changing atmospheric conditions. It is recommended that they include a cross-bar every 60 cm (or 2 feet) or so in each direction to help prevent any warping.

Traditional Stretched Canvas

A traditional stretched canvas requires framing. The tacks or staples show on the sides of the finished piece. Traditional canvases also tend to have a shallow profile. They are usually only about half an inch thick from the back of the canvas to the front.

Gallery Wrapped Canvas

This is a very modern style of stretching canvas. The canvas is wrapped around two edges of the stretcher bars and secured at the back where the staples or tacks can't show. Often the sides are painted.  No visible staples or nails means a neat finish is achieved and no framing is required.  Usually this style has quite a deep profile, more than an inch thick from the back of the canvas to the front, though they can also be shallow. The deep profile is the current trend.

Artists love gallery wrapped canvas as their artworks are ready to hang as soon as the varnish is dry. Many art collectors prefer it too as it allows them to skip the often substantial costs of framing. Anecdotally, gallery wrapped canvasses nearly put many framers out of business when it first came out as so many people suddenly didn't require their services. Though if you prefer your art in a frame, as some do, gallery wrapped canvas can be framed if you want.

Unstretched Canvas

It was a revelation to me when I was introduced to the idea of working on unstretched canvas. I was at the exhibition opening of a local artist who had oil pastel paintings on massive canvasses about 1 x 2 m. They were unstretched and looked wonderful.

Depending on your point of view, unstretched canvas is either fabulous or awful to paint on. It has a very different working feel to the drum-like bounce of a stretched canvas. To me it's wonderful and predictable. The give in the surface of a stretched canvas is something I find disconcerting. Different artists, different preferences. I guess it's like working on fabric textured board or paper.

For the artist there are some significant advantages to working on canvas unstretched. There are time savings as no pre-stretching is required. There are financial savings as no stretchers need to be bought. There are space savings as unused canvas can be stored rolled and once painted, can be stacked flat. Believe me, plain canvas takes up a LOT less room than a stack of stretched canvasses. And lastly, unstretched canvas is cheaper to post for a buyer as it weighs less.

For the art collector, unstretched canvas can be presented in a number of already familiar ways. It can be lightly stretched onto stretchers/strainers and ends up looking just like regular stretched canvas.  Or it can be framed just like any paper artwork. For extra rigidity, it can be mounted (glued) to board before framing. All very normal procedures for your framer.

The only downside to unstretched canvas that I can see is that someone needs to frame it.

More art technique articles

This article is one in an ongoing series of technical articles for artists, all archived together and accessible from here. The topics range from details on materials, to the business of art, to specific art techniques. Please make use of this resource.

Stretching canvas. All you need to know in one place. Why would you? What do you need? How is it done? (with a selection of curated videos).

Why would you?

Artists are always looking for ways to save money on materials without skimping on quality. Stretching your own canvas instead of buying it already stretched is a real dollar saver. It also allows an artist to have full control over the canvas they paint on and how it is prepared, and to have any size they choose. So not only can it be cheaper, but better quality too!

However, before getting outlandishly excited, stretching canvas does take time, so if you're not quick at it, perhaps buying ready-mades would be less expensive in the long run.  There is also the option of having canvas stretched for you by professionals. Obviously this costs though you get the exact specifications you want and can focus on painting, which is presumably what you do best.

What do you need?

How is it done?

Rather than write up a long winded explanation, I instead sought out a bunch of the most useful videos. There are an awful lot out there and most of them are awful! I've sat through as many as I could stand (about 20) to bring you the pick of the bunch.

A good general introduction

http://video.about.com/painting/How-to-Stretch-a-Canvas.htm

This is a 5 minute video which deals with stretching up to about the 2 minute mark has some neat tips with razor blades and misting sprays.

http://video.google.com/videoplay?docid=-271921060817845354#

Gallery wrapping of pre-painted canvas

http://www.youtube.com/watch?v=QkToBRa-O-U

A leisurely series on making stretcher bars and stretching canvas with plenty of handy tips

http://www.youtube.com/watch?v=t7iRiF1k7s4

http://www.youtube.com/watch?v=qY5-7a6QX8s

http://www.youtube.com/watch?v=nJ5H05A4184

http://www.youtube.com/watch?v=lKey4crHzmc

More art technique articles

This article is one in an ongoing series of technical articles for artists, all archived together and accessible from here. The topics range from details on materials, to the business of art, to specific art techniques. Please make use of this resource.

Thanks to Cara B Anderson for the photo.

Not all canvas 'for artists' is actually any good. Here's my notes from educating myself, written up into a readable form.

Rolled and Stretched and Primed

Canvas for artists is generally available in three forms. Stretched (and primed), unstretched and primed and unstretched and unprimed.

Naturally the form that saves an artist the most time is also the most expensive as all the preparation work has been done. I am talking here about the prestretched and preprimed canvases. There is nothing to do but take any wrapping off and get to being creative. This is a time saver that is not to be underestimated. The down side of ready to go canvas is that you have to take what's on offer. Which is not necessarily so bad. However, if you are after a non standard size or are particular about the weight of canvas on which you work or fussy about the gesso used and the surface finish you like to paint on, then the small number of options of prestretched canvas will probably drive you nuts.

So on to unstretched canvas. This is usually priced per length from a roll and cut when you buy. There is a lot more choice with this form of canvas, but some preparation work before painting.

Unstretched canvas does not have to be stretched onto a frame, but that is the conventional way. It is perfectly possible to work on canvas as you do a piece of paper. The stretching is to give a nice flat and smooth surface to paint on. Most painters like the bounce or give in a canvas stretched on a frame. I'm not going to give a how to on stretching canvas right here, but just say that if you buy canvas off a roll, you are more than likely going to stretch it onto a frame yourself. That takes time, of course. But you can make the frame any crazy size you want.

Canvas bought from a roll comes in two forms. Primed and unprimed. Primed means that once you've managed the stretching, you can get right to painting. Probably a good choice for an unusual sized frame where you're not too fussy about the gesso primer and the finish of the surface you paint on. Although it is certainly possible to reprime and/or sand a preprimed canvas to your heart's content.

The most labour intensive, for the artist, is to use unprimed unstretched canvas. Here you will be both stretching and priming your painting surface. If you are super particular about your painting surface, this one's for you. Though be warned, you will spend about half your 'painting time' in stretching and priming. But you will be able to get *exactly* what you want.

But There's Canvas and There's Canvas

That was meant to be a quick rundown on the forms that art canvas comes in. There is also variation in the actual canvas itself.

Jute or hessian

Jute or hessian is dirt cheap, has a very rough and open weaved texture and quickly weakens and becomes brittle with age. Not recommended for longevity! But what a texture.

Synthetic canvas

There are synthetic canvases usually made from polyester. Photo or giclee printing onto canvas tends to use synthetic canvases. They tend to have a much more even, tight weave which lacks character. Or bestows supreme consistency, depending on your taste. They are said (by the manufacturers) to stand up much better than cotton and linen when exposed to the elements and to be immune to bacteria, mildew and air pollution. Professional art supply stores call synthetic canvas 'cheap' (which is quite an advantage, I think) and tend to take a sneering tone toward it. I have not managed to turn up any unbiased information on it's artistic archival properties (ie, how it reacts over time to gesso and paint), however the tent and boating industries sing the praises of synthetic canvas, citing it's longevity over traditional cotton canvas. And if it performs in those tough environments, the omens seem good to me. One to watch.

On blended yarns: "Blends of fibre (ie cotton/polyster or cotton/linen) should be avoided as the final product is usually unstable due to the different weights, strengths and characteristics of the two yarns. They are only suitable if the blend is in the thread, and exists in equal weight ratio in the warp and weft." Thanks.

Cotton duck

This is the one to go for if you are buying cotton canvas. It is more tightly woven than plain canvas. Cotton canvas is the most conventional surface for painting (oils and acrylics obviously). It's properties are well known and it's available everywhere. It is flexible, easy to stretch properly and not too expensive. For large paintings it is too flexible. Large being over a metre square.

Linen

From the flax plant. Belgian is considered the best. If you are after absolute quality, this is the type of canvas to go for. Although linen is difficult to prime and stretch properly, it has the best archival properties. Because it has less flexibility than cotton, it expands and contracts less with changes in temperature and humidity. This means the paint on top has a much more stable surface and is far less likely to crack. And it's strong and stiff enough to support large paintings (over 1m square). Cotton fibres are short and flat (only 4 to 5cm long) whereas linen fibres are round and can range from 25 to 90cm in length. Many painters also like the uneven, natural texture of linen. Oh, and by the way, it's brown.

How Much Does It Weigh and Why You Might Care

Just to be clear here, I'm talking about cotton and linen. The synthetic canvases are much stronger per weight, so these figures don't apply.

7-8 oz. Beware! Not good enough for long lasting art. Often used for prestretched canvases. Usually poor quality loose weave and not very stable or strong. Avoid.

10 oz. The world's most popular art canvas weight. Fine for small artworks or situations where there will be little strain on the canvas. The main thing to watch out for is that most cotton canvas of this weight is twice as strong in one direction than the other (2:1 weave). Which reduces its dimensional stability. Warp and weft threads should be of equal weight, strength and material. The ideal yarn is closely and tightly woven with a square (1:1 or 2:2) weave.

12-15 oz. The best weight for painting. Nice and strong. Now you know.

More art technique articles

This article is one in an ongoing series of technical articles for artists, all archived together and accessible from here. The topics range from details on materials, to the business of art, to specific art techniques. Please make use of this resource.