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Hi @artyhag – Richard gave you some good advice. However, if you size over
the W&N prime you have applied, you will then either have to paint directly
over the untoothed size or put on more prime over the size. Both of these
options will probably be OK, but not great.
Another option would be to flip the canvas over, and then size and prime
that side. If it were me, I would redo on the other side, even if that means
taking the canvas off the stretcher bars and then putting back on. Sizing both
sides of the canvas would happen as a best practice anyway if one were to
adhere the canvas to a hard substrate, such as aluminum composite material (ACM).
I find the following to be the best compilation of technical information on
the web: Resources
(udel.edu) You can also ask MITRA questions directly on their forum.
Please let us know how this works out for you. We all learn a lot from each
@Marinos, I think the OP meant Golden GAC 100, which is a well-known and popular
size in the US.
Obviously, I respectfully disagree with the recommendation that an
acrylic ground is a good size for canvas. It may be OK, or adequate. It depends
on a lot of different factors which are not discussed here: brand and type of
primer, type and % of calcium, how many layers, how thick the layers, if the
canvas was raw or pre-primed, etc.
What is your source for thinking that Winsor and Newton acrylic gesso is
adequate as both a size and prime? Apart from W&N advertising it as such.
I have personally examined canvas with oil from oil paint applied to
the front. This oil leaked through the acrylic primer and saturated the back of
the canvas; the canvas was primed with acrylic prime “gesso” but was not sized.
This is well-known to cause the natural fiber canvas to rot, sometimes within 15
years. I have also seen the rot which oil causes to canvas. Fortunately, none
of these problems were in my own paintings.
From MITRA: “A ground layer, or primer, typically follows the size
layer in an easel painting.”
From the best source of material-handling I have found on the web:
Word - MITRA_Grounds_and_Primers.docx (udel.edu)
No need to make things too simplistic.
As an aside, I am in the process of repairing a 50 year old oil painting on
canvas which had rotted out from an inadequate size. I removed the canvas from stretcher
bars, cleaned and trimmed, and adhered to ACM. Now that it is stabilized, I will repaint
the areas from which the paint fell off completely because the canvas support
rotted away. The oil saturation and dark rot was clear and quite classic in
markings. I have about 5-6 hours in so far and estimate another 10 hours to
repaint. It is a beautiful piece, not mine, and I will photograph it before
starting in order to reduce the possibility I will deviate from the original painter’s
intentions. An ounce of prevention is worth a pound of cure, etc.
@Tassieguy – I
have no idea. I don’t use canvas, and so went to the Dick Blick website here in
the US, and read through several descriptions from the different brands of the acrylic
pre-primed canvas. All state they are acrylic primed, and none mention any
really expensive (5.5 yards, $1857US) brand, Artfix oil primed linen, does
not mention any size. “…Up to four layers of oil primer is meticulously
applied by hand and sanded to prevent peeling, flaking or cracking…the family
produces a conservator-grade painting surface that assures the artist's
expression will survive the passage of time… Double sizing provides
protection against oil paints, allowing uniform "breathing,"
which reduces paint film stress.”
How can oil-priming protect the fabric from oil paint? I assume that
a size is applied, but don’t know. If a size is not applied, then the product
description is quite deceiving. Also, if the fabric “breathes,” even uniformly,
then this will stress the paint film over time because oil paint does not “breathe.”
I think this is marketing BS.
I don’t use canvas anymore, but I was classically trained (lineage all the
way back to Titian, oddly enough), and was taught the reasons for choosing
materials. If I was using natural canvas now, I would prepare it myself using a
non-calcium containing acrylic size first to seal the natural fiber against the
oil. Calcium gives tooth; it is also absorbent. One wants a non-absorbent
sealing layer between the canvas and the oil. (Of course, I would also adhere
it to ACM, effectively sizing it on both sides.)
I watched the Mark Carder video on Youtube (“Canvas vs Panel”) and he does
not mention size at all. He discusses acrylic primer over linen canvas, followed
by a stain. Maybe this is the source which many here follow for canvas prep. Respectfully,
I think there are better ways of material handling.
I suggest that you contact both the manufacturer and the MITRA forum and
ask. If you do, please let us know what the response is.
Over my life, I have had the opportunity to examine the backs of dozens, if
not over a hundred, oil on canvas paintings at different institutions and
associations, and see for myself the different approaches to oil painting and
the results. Some painters, including well-regarded artists, simply didn’t care
about material handling. Oil seeped into the back within weeks – in other
words, almost immediately. Within the bounds of polite conversation, I asked
some of these painters about the oil on the back, and they didn’t know or care
BTW, I was trained that sizing is necessary on canvas; priming was not. I
was taught to prime for particular reasons. I once bought two commercially
prepared canvases on stretchers. I didn’t like the surface, could not figure
out if they were sized, and threw them away.
Desertsky said:Do you apply a primer as both size and primer? If so, how many layers do you use? Do you notice any seepage to the back of the canvas later on?
Acrylic gesso is a mixture of white pigment and some kind of filler (chalk, silica, etc.) and acrylic resin dispersed in water. It produces a soft, flexible non-absorbent surface that is technically not gesso(although it is commonly called that by its manufacturers). It can contain calcium carbonate (CaCO3) to increase the absorbency of the primer coat as well as titanium dioxide or "titanium white" as a whitening agent. It is sold premixed for both sizing and priming panels and flexible canvas for painting. Art supply manufacturers market canvases pre-primed with acrylic gesso.
Thanks, @Dencal, for the Jackson art information. I disagree (gasp) with
what is written there, but now I have a much better idea of the various sources.
I think a sealant should not contain an absorbent material such as calcium. The
Wiki information contains an actual error: an acrylic gesso which contains a
calcium-based filler will not be non-absorbent. The absorbency of the
calcium, depending on the amount used, will create an absorbent surface. This is one cause of sinking-in of oil paint. Some manufacturers are now offering
non-absorbent primers with reduced marble powder.
To @kingstonfineart’s point: if an oil painting starts to visibly degrade
in only 15-25 years, this is, in my opinion, a real problem, and not a concern
of “painting for the ages.” Rabbit skin glue is one kind of size, but it not
the only one. I use acrylic to size.
I think I am not overly stressed about archivality. I have found solutions
which are not much work,and satisfy me. To apply a size coat, and then a
primer, is no more work than applying two coats of a primer.
This has been an interesting discussion, and I have a much better understanding
of the sources of information people rely on.