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slad
04-28-2008, 01:57 PM
I've been reading Brian Gorst's The Complete Oil Painter and in describing the brown/grey color of linen he mentions that if sized throughly you could paint on it without priming. Has anyone done this? Is priming necessary if the canvas is well sized?

WFMartin
04-28-2008, 02:27 PM
I've been reading Brian Gorst's The Complete Oil Painter and in describing the brown/grey color of linen he mentions that if sized throughly you could paint on it without priming. Has anyone done this? Is priming necessary if the canvas is well sized?

Gosh, one would not bother to size a canvas, if one did not wish to apply an oil primer as the next, subsequent coat. And, since an oil primer is, basically, oil "paint", the answer is "no"--why bother applying an oil primer, if you wish to paint your subject directly upon the canvas, instead? It should work fine, I believe, and should have archival integrity, as well.

The rough texture of an unprimed canvas would bother me, but many artists prefer it, I realize.

Bill

Smokin
04-28-2008, 03:57 PM
Sizing is important, priming or gesso, not so much. Priming has a bit of practicality to it, you can modify how much tooth is on the canvas, how absorbent the surface will be toward your paints, and one can build a nice foundation to start from for sound archival practice. But omitting this step is not uncommon or a "bad practice". I do it all the time with paper & love it.

slad
04-28-2008, 04:37 PM
I've come back to oil painting after being away for quite a few years. I've always been taught to size and prime a canvas. I can see where priming does unify the surface but I do like the look of raw linen and thought I give this a try. Thanks for you replies.

Sal

hone
04-28-2008, 05:17 PM
I did that quite a bit as an art student. I was smitten with Francis Bacon's paintings and that was a procedure he used quite frequently... this was over 40 years ago and my paintings are not only in fine shape, they are still tight like a drum on their stretchers.

nit-wit
04-28-2008, 06:16 PM
As the size is transparent, if use a linen you'll have a ready made mid-toneish ground.

I've used just size quite a lot. It's not as rough a surface as you'd might expect. But certainly not the near friction less surface that Bill prefers. But I find after a few sessions the surface of an oil painting slickens up anyway.

The theory of size application is to apply in one direction for the first coat. And then brush the second coat 'across' at right angles to the first. In other words follow the waft and the weave. This should ensure thorough coverage. I do this for primer layers too.

Andrew

slad
04-28-2008, 10:50 PM
Is rabbit skin glue still a good size to use or has it been replaced with poly vinyl acetate?

1100ww
04-29-2008, 12:28 AM
Isn't Golden's "GAC 400" also considered a sort of sizing? And non-hygroscopic, at that:

GAC 400 Acrylic
A liquid acrylic polymer emulsion which dries to a hard, stiff film. When applied over a fabric support, such as cotton, linen or silk, the GAC 400 will serve to dramatically stiffen the support. This allows the artist to transform a lightweight fabric into a free-standing form that will hold its shape.

http://www.goldenpaints.com/products/medsadds/polymers/index.php

keenart
04-29-2008, 01:14 AM
Sizing is very important, but Gesso is an important safeguard against oil rot. Here is why; when you size the canvas there are always small hairs or strands of linen that are not completed sealed into the size and stick out like little wicks. This can occur even after 4 coats of size. Typically the old master scraped down the sized canvas to get rid of as many of these little wicks as possible before adding the gesso. And, then scraping down several coats of gesso to insure they were gone. Acrylics do not have this problem, but any oil based paint does.

If you paint directly on the sizing you stand a chance of the oils in the paint being drawn into the canvas similar. Some will say this is a controversial topic, but conservators conclude otherwise.

If you like the look of the dark linen, then use Sienna colored Gesso. Or use a white gesso and give it an imprimatura of the color of the linen. If this painting ever became a Museum piece your legacy will last, but you be the judge

Termini.
04-29-2008, 01:53 PM
Sizing is very important, but Gesso is an important safeguard against oil rot. Here is why; when you size the canvas there are always small hairs or strands of linen that are not completed sealed into the size and stick out like little wicks. This can occur even after 4 coats of size. Typically the old master scraped down the sized canvas to get rid of as many of these little wicks as possible before adding the gesso. And, then scraping down several coats of gesso to insure they were gone. Acrylics do not have this problem, but any oil based paint does.

If you paint directly on the sizing you stand a chance of the oils in the paint being drawn into the canvas similar. Some will say this is a controversial topic, but conservators conclude otherwise.

If you like the look of the dark linen, then use Sienna colored Gesso. Or use a white gesso and give it an imprimatura of the color of the linen. If this painting ever became a Museum piece your legacy will last, but you be the judge


Or one could simply sand the sized canvas, apply another thin coat of size, sand again, and a final coat of the same size. All very rapidly.

number19
04-30-2008, 03:25 AM
It is commonly said that the oils in oil paints can accelerate the aging and weakening of natural fibers like cotton, linen or hemp. Sizes like RSG or PVA sizes seal the canvas and isolate it from the paint layers. RSG also provides some desirable stiffness and body to the canvas and helps mitigate it's eventual loss of tension. Golden's GAC fabric stiffener is designed to emulate the stiffening, and bodying properties of RSG, although Golden admits it is not RSG's equal in these regards. Golden also says GAC 400 works well on cotton, but does not work well on linen. It is also not such a good sealer so that Golden advises the application of a coat of their GAC 100 ( a better sealer) on top of the GAC 400 coat. They then say to finish off with 2 or 3 coats of their acrylic gesso. Acrylic gesso used by itself does not stiffen the canvas so much. It also is not the best sealer unless used in at least 3 or 4 full or near full strength coats. From what I have heard it is fine to paint directly on a RSG sized canvas sized in 2 coats in the way nit-wit described.

nit-wit
04-30-2008, 05:12 AM
You can buy clear acrylic canvas sealer from Spectrum Oils, London.
Presumably this is acrylic primer without pigment. And dries transparent. I used it in the past but found it made the canvas a bit elastic - not terribly so and it may not bother you - I managed ok.

Spectrum sell it on the basis that it's for sealing canvas. The same as using size before oil priming.

Andrew

nit-wit
04-30-2008, 05:16 AM
Oh - I seem to have repeated no.19's advice - but Spectrum is perhaps a more affordable source. As they produce pigments, primers etc in bulk quantities. Beats messing around with 500ml of overpriced primer anyway.

Andrew

Termini.
04-30-2008, 12:17 PM
It is commonly said that the oils in oil paints can accelerate the aging and weakening of natural fibers like cotton, linen or hemp. Sizes like RSG or PVA sizes seal the canvas and isolate it from the paint layers. RSG also provides some desirable stiffness and body to the canvas and helps mitigate it's eventual loss of tension.

Yeap, it oxidizes those fibers. In addition to what you have stated, one of the main purposes of sizing a canvas is to in effect saturate and glue the fibers together, and thus reduce expansion and contraction from changes in humidity, and temperature.