Can I size after applying w&newton gesso to raw linen ??? HELP!

Can I size with Gold GAV 100 after painting raw linen canvases with w & newton Gesso?? Stupidly didn’t know about sizing eek and have made x20 beautiful canvases ready for oil painting - what can I do to correct mistake ??? Many thanks 


  • Yes, W&N gesso and Golden GAC 100 are all acrylic and will work to protect the linen
  • Great so Gac 100 over the top instead of underneath still works ok? 
  • Yes as far as I know. You can always email Golden. They are excellent at Technical Support.
  • Wow this site is brilliant - I just tripped over it and fell in - I’ve just got to work out how to use it lol thanks so much for your help as I was panicking!!!!
  • 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 (   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 other.

  • Why? The gesso is doing that job of sizing and piming.
  • @KingstonFineArt - You and I have different interpretations of what acrylic primer ("gesso") does. It is called a primer, not a primer/size.  Size, as a sealant, is made without any calcium tooth, and there is a structural reason for this. Apply enough layers (but what is enough?) and one's painting will probably be ok. 

    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? 
  • edited June 1
    What's Gold GAV 100 ? If you primed with w&n gesso you don't need to do anything else (as Kingston said). Drop a tiny bit of water on the canvas, if it's absorbed you might need to paint another layer of w&n gesso(supposing it's an acrylic primer). If it stays on the surface you're good to go. No need to make things complicated :)

  • @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:

    Adhesives-and-Sizes.pdf (

    Microsoft Word - MITRA_Grounds_and_Primers.docx (

    No need to make things too simplistic. :smiley:

    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. 

  • edited June 2
    @Desertsky, that's interesting. Do you know whether the commercially available pre-primed canvas we buy by the meter (by the 10 meter roll in my case) from art supply stores is sized before gesso is applied? I hope so. 
  • edited June 2
    Hello again :)
    The original question was if the canvases can be sized after gessoed. Well, one answer is not really. But in reality it's a Yes. As you suggested taking the canvas off the stretcher bars would be a good Idea if you want to do the whole process again properly. But chances is doing x20 canvases all over again and taking them off the strecher bars is highly unlikely in this situation :D

    I don't disagree with anything said here, I'm simply suggesting an easier, more realistic solution. 

    I personally use rabbit glue to size the surface and then an acrylic primer. I don't use w&n anymore but I still have a small amount left to prime surfaces mainly used for practice. It's all relevant.

    Btw thx for the resources/links posted it's all useful information

  • @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 sizing.

    Oddly, one 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. 

  • edited June 2
    Thanks, @desertsky. I will soon be in need of a new roll of canvas. What I shall do first is contact the manufacturer before I buy and ask them how they prepare their canvas. If they do not mention sizing before the application of acrylic gesso, I will ask them directly "Do you size the canvas before applying the gesso?"  If I get something like, "Well, with our gesso it's not necessary", I shall thank them and find a different manufacturer. If I cannot find one that sizes first, well, dammit, I suppose I'm going to have to do it myself. 

    If I have been painting on unsized canvas, my saving grace may be that I always paint my canvases with a fairly thick layer of acrylic paint over the acrylic gesso before painting in oils. (I like to paint the canvas in a shadow colour that occurs throughout the painting. I do this in acrylic because it dries quicker than oil). So,  with the two layers of acrylic gesso on the canvas already, and my own layer of acrylic paint, I'll have to hope that if the canvas has not been sized, it is isolated enough from the oil paint I've put on top. Still, I'm having visions of purchasers contacting me complaining that their canvases have rotted. I won't be able to give them their money back (the gallery gets a chunk of that) and so I'll have to undertake to paint them a new picture. I very much hope that I'm worrying unnecessarily. 
  • dencaldencal -
    edited June 2

    Modern canvas manufacture uses multiple coats of an acrylic dispersion medium with a resin added. This product provides an effective seal between the canvas and the oil paint. Examine the back of your paintings. Are there any oil stains?

    Sizes applied separately, based on animal glues absorb moisture from the back of the canvas and create an unstable support.


  • edited June 2
    Cheers, @dencal.  According to MITRA, sizing (not with animal skin glue) should be done anyway,  notwithstanding what the canvas manufacturers may say. Sizing should be done with a PVA polymer with a neutral pH. 

    That said,  I've never noticed any bleed through at the back of my paintings, and I've just now gone and checked some paintings which I've kept and which are more then 4 years old, and the backs are very clean, as new. So, either they have been properly sized and primed or my practice of applying an acrylic undercoat has saved the day.

    I'm still going to phone the manufacturers before I get a new roll of canvas.  If I'm not satisfied with what they say, I already stretch my own canvases, so sizing and priming won't be that much extra work. Unprimed canvas is cheaper.  And I'll have peace of mind.  

    Of course, I could switch to a rigid support like aluminium, but I'm so used to canvas, and I love it's texture and taut springiness under my brush. There's nothing wrong with rigid supports.  I just don't like the feel of them. 
  • @Denis - you are probably right. What is your source of information? If the "size" contains calcium, I would personally choose to not use it. I size with acrylic, not PVA. They both work well. 

    @Tassieguy, I think that acrylic painting before the oil layer will help greatly. Sizing and priming are not difficult; but it is more work than just buying already prepared canvas. If your canvas backs are clean after 4 years, then I think your canvas is properly sized. 

    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 about it.

    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. 

  • edited June 3
    Yes, that's why I don't buy those cheap, commercially prepared canvases that are available in all the big stores like K-Mart. They are alluringly cheap, but I wouldn't trust that they have been properly sized and primed. And the stretcher bars are very flimsy, and the canvas very thin. They may suit the hobbyist using acrylic but not the serious oil painter who wants their work to last.  

    I don't believe in getting overly stressed about archivality. Our duty to buyers entails that we do our best based on the latest scientific information. That's what I try to do. After that, posterity must look after itself. And if people whose job it is to think about these things decide that a work is worth preserving, then conservation science will find a way. If not, well, nothing lasts forever.
  • 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? 
    I haven't used a sizing (rabbit skin glue) for over 50 years. If you use gesso use three coats on canvas sanding each coat you have an excellent surface. When it comes to Linen I buy only double primed so it's not an issue. 

    I'm not one for painting for the ages. Does it matter? If so why? If it does matter to you buy good pre-made linen canvas.

    Drawing, composition and execution are the main things to focus on. People care for these things not the preparation.

    Paint on!
  • I’ve used acrylic gesso.  Two or three layers, depends on the surface. I then put a thinned medium warm tone of Holbein oil ground on that before painting.  
    I’ve painted on canvas and ACM.  In ACM I do put the oil ground on as well mostly because of how the oil paint adheres to it but also because it’s my medium tone background.
    I have used some store bought gallery wrapped canvas but the heavier canvas and thicker stretcher bars.
    Like @tassieguy I do like the canvas feel when applying paint but I don’t care for the surface texture.
    I haven’t seen any oil or paint seepage in any of the canvases so far after three years.
  • Desertsky

    @Denis - you are probably right. What is your source of information? 
    An acrylic dispersion ground will usually be called either acrylic gesso or acrylic primer and can fulfil the role of a size, primer and ground all in one. It seals the surface, it sticks to the surface even better than acrylic paint would and it provides a ground to paint on. It can be applied directly to a support without the need for a prior application of size. Most ready-prepared stretched canvases are Universal Primed, meaning that they have an acrylic ground so you can paint on them with oil or acrylic paint. 

    Acrylic gesso

    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.

  • I agree, @desertsky, that it has been an interesting and informative thread. I had no idea that (some?)  manufacturers who sell pre-primed canvas do not use a size layer. I just assumed that they did. I think that in, say, 20 years time, if paintings start falling of their rotting canvas, we'd be able to sue those manufacturers under consumer protection legislation on the basis that their product was not fit for purpose.  I doubt I'll be around for that, but I'll no longer take chances with pre-primed canvas and will size and prime my own from now on.  It's not too difficult or time consuming to do.  I'll save money by buying raw canvas (which I'll spend on size and gesso) and I'll have peace of mind knowing that I've done all I can to ensure longevity.
  • I have pre primed canvases that I painted 40 years or so ago and they are still fine.
  • And they'll probably be fine for as far into the future as anyone cares to look, @oilpainter. If the canvas had not been properly sealed you would have noticed problems by now - bleed through at the back, deterioration/rotting of the canvas, damage to the paint layer... 

    I think it's possible to get overly precious about archivality and worry when it's not necessary.
    Better to spend less time worrying and more time painting. We can only do our best with the time, knowledge  and resources we have available. After that it's up to posterity.  :)
  • Sorry to come into this thread so late! Very informative and helpful information. FYI, I too have several larger, inexpensive, store bought canvas oil paintings that I painted over 40 years ago that have no oil bleed/stains on the back. One painting does have some paint cracking in one area but that may have been caused by lean over fat and not due to canvas preparation. 
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